CONTRAINDICATIONS / PRECAUTIONS
General Information
NOTE: This monograph discusses the use of dutasteride; tamsulosin combination capsules for the treatment of symptomatic benign prostatic hyperplasia (BPH). Clinicians may wish to consult the individual drug monographs for more information.
Dutasteride; tamsulosin is contraindicated in patients with a known hypersensitivity to dutasteride (e.g., angioedema) or any ingredient in the preparation. Cross-sensitivity with other 5-alpha-reductase inhibitors is possible.
Females, pregnancy
Dutasteride; tamsulosin is not indicated for use in females, and the use of this product during pregnancy is contraindicated. Dutasteride and other 5-alpha-reductase inhibitors inhibit the conversion of testosterone to dihydrotestosterone (DHT), which can cause abnormalities in the external genitalia of the male fetus. In animal reproduction studies, dutasteride inhibited the normal development of male fetus external genitalia in the offspring of rats and rabbits administered the drug during organogenesis at doses less than the maximum recommended human dose (MRHD). At dutasteride doses 15-times the MRHD, prolonged pregnancy, decreased reproductive organ weights, and delayed puberty in male offspring were observed in rat. Pregnant women or women trying to conceive should not handle dutasteride; tamsulosin capsules because dutasteride is absorbed through the skin and may result in fetal exposure. If skin contact with a leaking capsule occurs, the affected area should be washed with soap and water immediately. Dutasteride is secreted into male semen; however, the amount of dutasteride in semen that is available for vaginal absorption is estimated to be less than 100-times the concentrations that produced abnormalities in the genitalia of male offspring during animal studies. In addition, dutasteride is more than 96% protein bound in human semen, which may decrease vaginal absorption of the drug. Tamsulosin has not been associated with development effects following administration to rats and rabbits during the period of organogenesis.
Breast-feeding
Dutasteride; tamsulosin is not intended for use in females, which would preclude use of the drug in women who are breast-feeding; it is not known whether dutasteride or tamsulosin is excreted in human milk.
Children, infants, neonates
Dutasteride; tamsulosin is not intended for use in neonates, infants, children, and adolescents under 18 years of age. Safety and effectiveness have not been established in this age group.
Geriatric, orthostatic hypotension, renal disease, renal failure, renal impairment, syncope
Dutasteride; tamsulosin should be used cautiously in patients with orthostatic hypotension, vertigo, or syncope. The signs and symptoms of orthostasis (postural hypotension, dizziness, and vertigo) were more frequently reported in tamsulosin-treated patients than those receiving placebo. As with other alpha-adrenergic blocking agents, there is a potential risk of syncope and patients should be cautioned to avoid situations where injury could result should syncope occur. Patients with renal impairment, renal failure or other renal disease and geriatric patients should also be monitored carefully for exaggerated hypotensive effects (e.g., first dose effect). Differences in safety and efficacy were not noted between patients > 65 years of age and younger patients.
Prostate cancer, urinary tract obstruction
Dutasteride reduces total serum prostate specific antigen (PSA) by about 40% after 3 months of treatment and 50% after 6, 12, and 24 months of treatment. This decrease is predictable over the entire range of PSA values, but may vary in individual patients. It is recommended that a new baseline PSA concentration be established after 3—6 months for interpretation of serial PSAs in men taking dutasteride; tamsulosin. This new baseline PSA should be used to assess potentially cancer-related changes in PSA. To interpret an isolated PSA value in a man treated with dutasteride for 6 months or more, the PSA value should be doubled for comparison with normal values in untreated men. The free-to-total PSA ratio (percent free PSA) remains constant at month 12, even under the influence of dutasteride. If clinicians elect to use percent free PSA as an aid in the detection of prostate cancer in men receiving dutasteride, no adjustment to its value appears necessary. Administration of dutasteride; tamsulosin results in similar changes to total PSA as dutasteride monotherapy. In June 2011, a review of two large, randomized controlled trials, the Prostate Cancer Prevention Trial (PCPT) and the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) trial prompted the FDA to alert healthcare professionals of the potential risk of an increased incidence of high-grade prostate cancer in patients receiving finasteride or dutasteride treatment. Results from the REDUCE trial showed that men receiving dutasteride had a 23% decreased risk of being diagnosed with prostate cancer when compared to placebo (p < 0.0001); however, the risk reduction was limited to Gleason score (GS) <= 6 cancers. There was an increased incidence of GS 8—10 prostate cancers with dutasteride compared to placebo (1% vs. 0.5%, respectively). Therefore, in initiating or continuing treatment with dutasteride; tamsulosin, clinicians should weigh the known benefits of treatment against the potential risk and be aware that dutasteride may increase the risk of high-grade prostate cancer. Further, lower urinary tract symptoms of BPH can be indicative of other urological diseases, including prostate cancer. Patients should be assessed to rule out other urological diseases prior to treatment with dutasteride and periodically thereafter. Patients with a large residual urinary volume and/or severely diminished urinary flow may not be good candidates for 5-alpha-reductase inhibitor therapy and should be carefully monitored for urinary tract obstruction.
Blood donation
Males treated with dutasteride; tamsulosin should not undergo blood donation until at least 6 months have passed following their last dose. The purpose of this deferred period is to prevent administration of dutasteride to a pregnant female receiving a blood transfusion. Serum levels of dutasteride are detectable for 4—6 months following termination of therapy.
Ocular surgery
Patients receiving or who have previously received treatment with dutasteride; tamsulosin or other alpha-1 blockers may be at risk for intraoperative floppy iris syndrome during surgery for cataracts (ocular surgery). Intraoperative floppy iris syndrome is a small pupil syndrome variant that is characterized by a flaccid iris that billows in response to intraoperative irrigation currents, progressive intraoperative miosis despite preoperative dilation with standard mydriatic drugs, and potential prolapse of the iris toward the phacoemulsification incisions. There does not appear to be a benefit of stopping alpha-1 blocker therapy prior to cataract surgery, but ophthalmologists should be prepared for possible modifications to their surgical technique such as the use of iris hooks, iris dilator rings, or viscoelastic substances.
Sulfonamide hypersensitivity
Tamsulosin is a non-arylamine sulfonamide derivative. In patients with sulfonamide hypersensitivity, allergic reaction to tamsulosin has been rarely reported. If a patient reports a serious or life threatening sulfonamide allergy, the manufacturer advises caution when administering dutasteride; tamsulosin. However, tamsulosin is not contraindicated for use in patients with sulfonamide allergy. Based on clinical trials and post-marketing experience with tamsulosin, the potential for cross-reactivity in patients with sulfonamide allergy has not been established. In post-marketing experience, allergic-type reactions (such as skin rash, pruritus, urticaria, and angioedema of the tongue, lips, and face) have been reported in some cases, and, in very rare cases, in patients who had a history of sulfa allergy (manufacturer data on file). According to the manufacturer, clinical trials with tamsulosin did not screen for or exclude patients with a history of sulfonamide allergy; therefore, the actual potential for sulfonamide cross-reactivity with tamsulosin is unknown. Non-arylamine sulfonamide derivatives (e.g., tamsulosin) have been reported to be proposed to have a lower risk of allergic reactions in patients with sulfonamide allergy, presumably due to the lack of one of the proposed structural sites of action for sulfonamide allergy (arylamine group in the N4 position). One large retrospective cohort study has reported that in patients with the presence of an allergic reaction after exposure to a sulfonamide antibiotic, 9.9% had an allergic reaction after receiving a non-antibiotic sulfonamide derivative, and 1.6% of patients who lacked an allergic reaction after sulfonamide antibiotic exposure had an allergic reaction after administration of a non-antibiotic sulfonamide derivative (adjusted odds ratio 2.8; 95% CI, 2.1—3.7). A causal relationship between sulfonamide hypersensitivity and allergic reactions with non-arylamine sulfonamide derivatives has not been definitively established and remains controversial. In general, patients with a documented sulfonamide allergy are considered to be predisposed for development of allergic drug reactions. Until further data are available, caution is prudent when administering sulfonamide derivatives to patients with a documented sulfonamide hypersensitivity.
Hepatic disease
Dutasteride; tamsulosin should be used with caution in patients with hepatic disease; data are limited regarding the incidence of adverse effects or drug accumulation in these patients. Dutasteride is extensively metabolized by the liver and has a half-life of about 5 weeks at steady state. Patients with mild to moderate impairment do not require an adjustment in tamsulosin dosage. Tamsulosin has not been studied in patients with severe hepatic impairment and cautious use is warranted in this population.
Priapism
Rarely (probably less than 1 in 50,000), tamsulosin, like other alpha adrenergic antagonists, has been associated with priapism (persistent painful penile erection unrelated to sexual activity). Priapism, if not treated promptly, can result in irreversible damage to the erectile tissue. Patients who have an erection lasting greater than 4 hours, whether painful or not, should seek emergency medical attention.
Infertility
The clinical significance of the effect of dutasteride; tamsulosin on semen and sexual function in men is not fully known; consider the potential effects when assessing a male with infertility. The effects of dutasteride 0.5 mg/day on semen characteristics were evaluated in normal male volunteers aged 18 to 52 (n = 27 dutasteride, n = 23 placebo) throughout 52 weeks of treatment and 24 weeks of post-treatment follow-up. At 52 weeks, the mean percent reductions from baseline in total sperm count, semen volume, and sperm motility were 23%, 26%, and 18%, respectively, in the dutasteride group when adjusted for changes from baseline in the placebo group. Sperm concentration and sperm morphology were unaffected. After 24 weeks of follow-up, the mean percent change in total sperm count in the dutasteride group remained 23% lower than baseline. While mean values for all semen parameters at all time-points remained within the normal ranges and did not meet predefined criteria for a clinically significant change (30%), 2 subjects in the dutasteride group had decreases in sperm count of greater than 90% from baseline at 52 weeks, with partial recovery at the 24-week follow-up. The effects of tamsulosin on sperm counts or sperm function have not been evaluated; however, tamsulosin has been associated with abnormal ejaculation (i.e., ejaculation failure, ejaculation disorder, retrograde ejaculation, and decreased ejaculation) in men. In animal studies, significantly reduced fertility was observed in male rats treated with single or multiple daily doses of tamsulosin (50-times the human exposure with maximum therapeutic dose). The mechanism for the decreased male fertility was thought to be an effect of the drug on the vaginal plug formation possibly due to changes in semen content or impairment of ejaculation; male infertility was reversible upon treatment discontinuation. In animal studies involving female rats, single doses of tamsulosin (50-times the human exposure with maximum therapeutic dose) resulted in reduced fertility considered to be associated with impairments in fertilization.
DRUG INTERACTIONS
Abiraterone: (Moderate) Monitor for an increase in tamsulosin-related adverse reactions if coadministration with abiraterone is necessary. Tamsulosin is a CYP2D6 substrate and abiraterone is a moderate CYP2D6 inhibitor. The effects of coadministration with a moderate CYP2D6 on the pharmacokinetics of tamsulosin have not been evaluated; however, the manufacturer of tamsulosin recommends caution with use.
Acebutolol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Acetaminophen; Aspirin; Diphenhydramine: (Moderate) Use caution if coadministration of diphenhydramine with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and diphenhydramine is a moderate CYP2D6 inhibitor.
Acetaminophen; Chlorpheniramine: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as chlorpheniramine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Acetaminophen; Chlorpheniramine; Dextromethorphan: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as chlorpheniramine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as chlorpheniramine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as chlorpheniramine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Acetaminophen; Chlorpheniramine; Phenylephrine : (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as chlorpheniramine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Acetaminophen; Diphenhydramine: (Moderate) Use caution if coadministration of diphenhydramine with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and diphenhydramine is a moderate CYP2D6 inhibitor.
Adagrasib: (Major) Concurrent use of tamsulosin and adagrasib is not recommended due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension, dizziness, and vertigo. Tamsulosin is a CYP3A and CYP2D6 substrate and adagrasib is a strong CYP3A and moderate CYP2D6 inhibitor. Concomitant treatment with another strong CYP3A inhibitor increased the AUC of tamsulosin by 2.8-fold. (Moderate) Monitor for dutasteride-related adverse reactions if coadministration with adagrasib is necessary. Dutasteride is a CYP3A substrate and adagrasib is a strong CYP3A inhibitor. Although the effect of strong CYP3A inhibitors on dutasteride has not been studied, dutasteride exposure may increase.
Alpha-blockers: (Major) Tamsulosin should not be administered in combination with other alpha-blockers. The pharmacokinetic and pharmacodynamic interactions between tamsulosin and other alpha-blockers (used for high blood pressure or for benign prostatic hyperplasia) have not been determined. However, interactions or side effects (dizziness, hypotension, syncope, etc.) may be expected from the duplication of pharmacologic effects.
Ambrisentan: (Minor) Because symptoms of orthostasis (e.g., postural hypotension, dizziness, vertigo) are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents.
Amiodarone: (Moderate) Dutasteride is metabolized by CYP3A4 and CYP3A5 isoenzymes. The clearance of dutasteride may be reduced when co-administered with CYP3A4 inhibitors, such as amiodarone. (Moderate) Use caution if coadministration of amiodarone with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP3A4 and CYP2D6 substrate and amiodarone is a moderate CYP3A4 and CYP2D6 inhibitor. The effects of concomitant administration of a moderate CYP3A4 and CYP2D6 inhibitor on the pharmacokinetics of tamsulosin have not been evaluated, but tamsulosin exposure may increase based on the effects of strong CYP3A4 and CYP2D6 inhibition.
Amlodipine: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Amlodipine; Atorvastatin: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Amlodipine; Benazepril: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Amlodipine; Celecoxib: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Amlodipine; Olmesartan: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Amlodipine; Valsartan: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Amlodipine; Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Amobarbital: (Moderate) Concurrent use of amobarbital with antihypertensive agents may lead to hypotension. Monitor for decreases in blood pressure during times of coadministration.
Amoxicillin; Clarithromycin; Omeprazole: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of clarithromycin. Tamsulosin is extensively metabolized by CYP3A4 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use with a strong CYP3A4 inhibitor, such as clarithromycin, should be avoided.
Aprepitant, Fosaprepitant: (Moderate) Use caution if tamsulosin and aprepitant, fosaprepitant are used concurrently and monitor for an increase in tamsulosin-related adverse effects for several days after administration of a multi-day aprepitant regimen. Tamsulosin is a CYP3A4 substrate. Aprepitant, when administered as a 3-day oral regimen (125 mg/80 mg/80 mg), is a moderate CYP3A4 inhibitor and inducer and may increase plasma concentrations of tamsulosin. For example, a 5-day oral aprepitant regimen increased the AUC of another CYP3A4 substrate, midazolam (single dose), by 2.3-fold on day 1 and by 3.3-fold on day 5. After a 3-day oral aprepitant regimen, the AUC of midazolam (given on days 1, 4, 8, and 15) increased by 25% on day 4, and then decreased by 19% and 4% on days 8 and 15, respectively. As a single 125 mg or 40 mg oral dose, the inhibitory effect of aprepitant on CYP3A4 is weak, with the AUC of midazolam increased by 1.5-fold and 1.2-fold, respectively. After administration, fosaprepitant is rapidly converted to aprepitant and shares many of the same drug interactions. However, as a single 150 mg intravenous dose, fosaprepitant only weakly inhibits CYP3A4 for a duration of 2 days; there is no evidence of CYP3A4 induction. Fosaprepitant 150 mg IV as a single dose increased the AUC of midazolam (given on days 1 and 4) by approximately 1.8-fold on day 1; there was no effect on day 4. Less than a 2-fold increase in the midazolam AUC is not considered clinically important.
Artemether; Lumefantrine: (Moderate) Use caution when administering tamsulosin with a strong CYP2D6 inhibitor such as artemether; lumefantrine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure. If concomitant use in necessary, monitor patient closely for increased side effects.
Atazanavir: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of anti-retroviral protease inhibitors. Tamsulosin is extensively metabolized by CYP3A4 and CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use of tamsulosin with a strong CYP3A4 inhibitor, or an agent with both CYP3A4 and CYP2D6 inhibitor activity, should be avoided. (Moderate) Concurrent administration of dutasteride with protease inhibitors may result in elevated dutasteride plasma concentrations. Dutasteride is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Atazanavir; Cobicistat: (Major) Concurrent use of tamsulosin and cobicistat is not recommended due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension, dizziness, and vertigo. Tamsulosin is metabolized by CYP3A4 and CYP2D6 hepatic enzymes. Cobicistat is a strong inhibitor of CYP3A4 and a CYP2D6 inhibitor. Concomitant treatment with another strong CYP3A4 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively. (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of anti-retroviral protease inhibitors. Tamsulosin is extensively metabolized by CYP3A4 and CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use of tamsulosin with a strong CYP3A4 inhibitor, or an agent with both CYP3A4 and CYP2D6 inhibitor activity, should be avoided. (Moderate) Concurrent administration of dutasteride with protease inhibitors may result in elevated dutasteride plasma concentrations. Dutasteride is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. Caution and close monitoring are advised if these drugs are administered together. (Moderate) The plasma concentrations of dutasteride may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as impotence or libido decrease, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while dutasteride is a CYP3A4 substrate.
Atenolol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Atenolol; Chlorthalidone: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Avanafil: (Moderate) Due to the potential for symptomatic hypotension, patients should be stable on tamsulosin therapy before initiating therapy with the lowest dose of avanafil. Conversely, patients already receiving an optimized dose of avanafil should be started on the lowest dose of tamsulosin; increases in the alpha-blocker dose should be done in a stepwise fashion. Other variables, such as intravascular volume depletion, concurrent antihypertensive therapy, or evidence of hemodynamic instability with alpha-blocker monotherapy, may affect the safety of concomitant use of avanafil and tamsulosin.
Bendroflumethiazide; Nadolol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Berotralstat: (Moderate) Use caution if coadministration of berotralstat with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg. The systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP3A4 and CYP2D6 substrate and berotralstat is a moderate CYP3A4 and CYP2D6 inhibitor. The effects of concomitant administration of a moderate CYP3A4/CYP2D6 inhibitor on the pharmacokinetics of tamsulosin have not been evaluated, but tamsulosin exposure may increase based on the effects of strong CYP3A4 inhibition.
Beta-blockers: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Betaxolol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Bisoprolol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Bisoprolol; Hydrochlorothiazide, HCTZ: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Brimonidine; Timolol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Bupropion: (Moderate) Use caution if coadministration of bupropion with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and bupropion is a strong CYP2D6 inhibitor. Concomitant treatment with another strong CYP2D6 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 1.3 and 1.6, respectively.
Bupropion; Naltrexone: (Moderate) Use caution if coadministration of bupropion with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and bupropion is a strong CYP2D6 inhibitor. Concomitant treatment with another strong CYP2D6 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 1.3 and 1.6, respectively.
Calcium-channel blockers: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Carteolol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Carvedilol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Ceritinib: (Major) Concurrent use of tamsulosin and ceritinib is not recommended due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension, dizziness, and vertigo. Tamsulosin is extensively metabolized by CYP3A4 hepatic enzymes, and strong inhibitors of CYP3A4 like ceritinib are expected to significantly raise tamsulosin concentrations. Concomitant treatment with another strong CYP3A4 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively. (Moderate) Monitor for dutasteride-related adverse reactions if coadministration with ceritinib is necessary. Dutasteride is a CYP3A4 substrate and ceritinib is a strong CYP3A4 inhibitor. Although the effect of strong CYP3A4 inhibitors on dutasteride has not been studied, dutasteride exposure may increase.
Chloramphenicol: (Moderate) Use caution when administering tamsulosin with a moderate CYP3A4 inhibitor such as chloramphenicol. Tamsulosin is extensively metabolized by CYP3A4 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure; interactions with moderate CYP3A4 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Chlorpheniramine: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as chlorpheniramine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Chlorpheniramine; Codeine: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as chlorpheniramine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Chlorpheniramine; Dextromethorphan: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as chlorpheniramine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as chlorpheniramine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as chlorpheniramine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Chlorpheniramine; Dihydrocodeine; Phenylephrine: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as chlorpheniramine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Chlorpheniramine; Hydrocodone: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as chlorpheniramine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Chlorpheniramine; Ibuprofen; Pseudoephedrine: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as chlorpheniramine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Chlorpheniramine; Phenylephrine: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as chlorpheniramine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Chlorpheniramine; Pseudoephedrine: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as chlorpheniramine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Chlorpromazine: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as chlorpromazine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Cimetidine: (Moderate) Dutasteride is metabolized by CYP3A4 enzyme. The clearance of dutasteride may be reduced when co-administered with CYP3A4 inhibitors, such as cimetidine. (Moderate) Use caution if coadministration of cimetidine with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Treatment with cimetidine 400 mg every 6 hours for 6 days in healthy volunteers (n = 10) resulted in a 26% decrease in the clearance of tamsulosin, which resulted in a 44% increase in tamsulosin AUC. Tamsulosin is a CYP2D6 and CYP3A substrate and cimetidine is a weak CYP2D6 and CYP3A inhibitor.
Cinacalcet: (Moderate) Use caution if coadministration of cinacalcet with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and cinacalcet is a moderate CYP2D6 inhibitor.
Clarithromycin: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of clarithromycin. Tamsulosin is extensively metabolized by CYP3A4 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use with a strong CYP3A4 inhibitor, such as clarithromycin, should be avoided.
Clevidipine: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Cobicistat: (Major) Concurrent use of tamsulosin and cobicistat is not recommended due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension, dizziness, and vertigo. Tamsulosin is metabolized by CYP3A4 and CYP2D6 hepatic enzymes. Cobicistat is a strong inhibitor of CYP3A4 and a CYP2D6 inhibitor. Concomitant treatment with another strong CYP3A4 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively. (Moderate) The plasma concentrations of dutasteride may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as impotence or libido decrease, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while dutasteride is a CYP3A4 substrate.
Conivaptan: (Moderate) Use caution if coadministration of conivaptan with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP3A substrate and conivaptan is a moderate CYP3A inhibitor.
Crizotinib: (Moderate) Use caution if coadministration of crizotinib with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP3A4 substrate and crizotinib is a moderate CYP3A4 inhibitor. The effects of concomitant administration of a moderate CYP3A4 inhibitor on the pharmacokinetics of tamsulosin have not been evaluated, but tamsulosin exposure may increase based on the effects of strong CYP3A4 inhibition.
Cyclosporine: (Moderate) Use caution when administering tamsulosin with a moderate CYP3A4 inhibitor such as cyclosporine. Tamsulosin is extensively metabolized by CYP3A4 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure; interactions with moderate CYP3A4 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Dacomitinib: (Moderate) Use caution if coadministration of dacomitinib with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and dacomitinib is a strong CYP2D6 inhibitor. Concomitant treatment with another strong CYP2D6 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 1.3 and 1.6, respectively.
Danazol: (Moderate) Use caution when administering tamsulosin with a moderate CYP3A4 inhibitor such as danazol. Tamsulosin is extensively metabolized by CYP3A4 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure; interactions with moderate CYP3A4 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Darifenacin: (Moderate) Use caution if coadministration of darifenacin with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and darifenacin is a moderate CYP2D6 inhibitor. The effects of concomitant administration of a moderate CYP2D6 inhibitor on the pharmacokinetics of tamsulosin have not been evaluated, but tamsulosin exposure may increase based on the effects of strong CYP2D6 inhibition.
Darunavir: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of anti-retroviral protease inhibitors. Tamsulosin is extensively metabolized by CYP3A4 and CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use of tamsulosin with a strong CYP3A4 inhibitor, or an agent with both CYP3A4 and CYP2D6 inhibitor activity, should be avoided. (Moderate) Concurrent administration of dutasteride with protease inhibitors may result in elevated dutasteride plasma concentrations. Dutasteride is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Darunavir; Cobicistat: (Major) Concurrent use of tamsulosin and cobicistat is not recommended due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension, dizziness, and vertigo. Tamsulosin is metabolized by CYP3A4 and CYP2D6 hepatic enzymes. Cobicistat is a strong inhibitor of CYP3A4 and a CYP2D6 inhibitor. Concomitant treatment with another strong CYP3A4 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively. (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of anti-retroviral protease inhibitors. Tamsulosin is extensively metabolized by CYP3A4 and CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use of tamsulosin with a strong CYP3A4 inhibitor, or an agent with both CYP3A4 and CYP2D6 inhibitor activity, should be avoided. (Moderate) Concurrent administration of dutasteride with protease inhibitors may result in elevated dutasteride plasma concentrations. Dutasteride is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. Caution and close monitoring are advised if these drugs are administered together. (Moderate) The plasma concentrations of dutasteride may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as impotence or libido decrease, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while dutasteride is a CYP3A4 substrate.
Darunavir; Cobicistat; Emtricitabine; Tenofovir alafenamide: (Major) Concurrent use of tamsulosin and cobicistat is not recommended due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension, dizziness, and vertigo. Tamsulosin is metabolized by CYP3A4 and CYP2D6 hepatic enzymes. Cobicistat is a strong inhibitor of CYP3A4 and a CYP2D6 inhibitor. Concomitant treatment with another strong CYP3A4 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively. (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of anti-retroviral protease inhibitors. Tamsulosin is extensively metabolized by CYP3A4 and CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use of tamsulosin with a strong CYP3A4 inhibitor, or an agent with both CYP3A4 and CYP2D6 inhibitor activity, should be avoided. (Moderate) Concurrent administration of dutasteride with protease inhibitors may result in elevated dutasteride plasma concentrations. Dutasteride is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. Caution and close monitoring are advised if these drugs are administered together. (Moderate) The plasma concentrations of dutasteride may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as impotence or libido decrease, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while dutasteride is a CYP3A4 substrate.
Dasabuvir; Ombitasvir; Paritaprevir; Ritonavir: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of anti-retroviral protease inhibitors. Tamsulosin is extensively metabolized by CYP3A4 and CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use of tamsulosin with a strong CYP3A4 inhibitor, or an agent with both CYP3A4 and CYP2D6 inhibitor activity, should be avoided. (Moderate) Concurrent administration of dutasteride with protease inhibitors may result in elevated dutasteride plasma concentrations. Dutasteride is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Delavirdine: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of delavirdine. Tamsulosin is extensively metabolized by CYP2D6 and CYP3A4 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Therefore, concomitant use with drugs that inhibit both CYP2D6 and CYP3A4, such as delavirdine, should be avoided. (Moderate) Monitor for common side effects of dutasteride, such as libido decrease, breast tenderness, or erectile dysfunction when chronic, potent inhibitors of CYP3A4 like delavirdine are used concomitantly. The effect of potent CYP3A4 inhibitors on the metabolism of dutasteride has not been studied. However, because dutasteride is metabolized by CYP3A4 and CYP3A5 isoenzymes, chronic coadministration with potent CYP3A4 enzyme inhibitors may result in elevated concentrations of dutasteride.
Dextromethorphan; Bupropion: (Moderate) Use caution if coadministration of bupropion with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and bupropion is a strong CYP2D6 inhibitor. Concomitant treatment with another strong CYP2D6 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 1.3 and 1.6, respectively.
Dextromethorphan; Diphenhydramine; Phenylephrine: (Moderate) Use caution if coadministration of diphenhydramine with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and diphenhydramine is a moderate CYP2D6 inhibitor.
Dextromethorphan; Quinidine: (Moderate) Use caution when administering tamsulosin with a strong CYP2D6 inhibitor such as quinidine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure. If concomitant use in necessary, monitor patient closely for increased side effects.
Diltiazem: (Moderate) Dutasteride is metabolized by CYP3A4 enzyme and the clearance of dutasteride may be reduced when co-administered with the CYP3A4 inhibitor diltiazem. (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Diphenhydramine: (Moderate) Use caution if coadministration of diphenhydramine with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and diphenhydramine is a moderate CYP2D6 inhibitor.
Diphenhydramine; Ibuprofen: (Moderate) Use caution if coadministration of diphenhydramine with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and diphenhydramine is a moderate CYP2D6 inhibitor.
Diphenhydramine; Naproxen: (Moderate) Use caution if coadministration of diphenhydramine with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and diphenhydramine is a moderate CYP2D6 inhibitor.
Diphenhydramine; Phenylephrine: (Moderate) Use caution if coadministration of diphenhydramine with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and diphenhydramine is a moderate CYP2D6 inhibitor.
Dorzolamide; Timolol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Doxazosin: (Major) Tamsulosin should not be administered in combination with other alpha-blockers. The pharmacokinetic and pharmacodynamic interactions between tamsulosin and other alpha-blockers (used for high blood pressure or for benign prostatic hyperplasia) have not been determined. However, interactions or side effects (dizziness, hypotension, syncope, etc.) may be expected from the duplication of pharmacologic effects.
Dronedarone: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of dronedarone. Tamsulosin is extensively metabolized by CYP2D6 and CYP3A4 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Therefore, concomitant use with drugs that inhibit both CYP2D6 and CYP3A4, such as dronedarone, should be avoided.
Duloxetine: (Moderate) Use caution if coadministration of duloxetine with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and duloxetine is a moderate CYP2D6 inhibitor.
Elbasvir; Grazoprevir: (Moderate) Administering tamsulosin with elbasvir; grazoprevir may result in elevated tamsulosin plasma concentrations. Tamsulosin is a substrate of CYP3A; grazoprevir is a weak CYP3A inhibitor. If these drugs are used together, closely monitor for signs of adverse events.
Eliglustat: (Moderate) Coadministration of tamsulosin and eliglustat may result in increased concentrations of tamsulosin. Use tamsulosin with caution in patients receiving eliglustat, particularly if the tamsulosin dose is greater than 0.4 mg, and monitor closely for tamsulosin-related adverse effects including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 and CYP3A4 substrate; eliglustat is a CYP2D6 inhibitor.
Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Alafenamide: (Major) Concurrent use of tamsulosin and cobicistat is not recommended due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension, dizziness, and vertigo. Tamsulosin is metabolized by CYP3A4 and CYP2D6 hepatic enzymes. Cobicistat is a strong inhibitor of CYP3A4 and a CYP2D6 inhibitor. Concomitant treatment with another strong CYP3A4 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively. (Moderate) The plasma concentrations of dutasteride may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as impotence or libido decrease, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while dutasteride is a CYP3A4 substrate.
Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Disoproxil Fumarate: (Major) Concurrent use of tamsulosin and cobicistat is not recommended due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension, dizziness, and vertigo. Tamsulosin is metabolized by CYP3A4 and CYP2D6 hepatic enzymes. Cobicistat is a strong inhibitor of CYP3A4 and a CYP2D6 inhibitor. Concomitant treatment with another strong CYP3A4 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively. (Moderate) The plasma concentrations of dutasteride may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as impotence or libido decrease, is recommended during coadministration. Cobicistat is a strong CYP3A4 inhibitor, while dutasteride is a CYP3A4 substrate.
Erythromycin: (Moderate) Dutasteride is metabolized by CYP3A4 enzyme and CYP3A5 isoenzymes. The clearance of dutasteride may be reduced when co-administered with CYP3A4 inhibitors, such as erythromycin. (Moderate) Use caution if coadministration of erythromycin with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP3A substrate and erythromycin is a moderate CYP3A inhibitor.
Escitalopram: (Moderate) Use caution if coadministration of escitalopram with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and escitalopram is a moderate CYP2D6 inhibitor.
Esmolol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Everolimus: (Moderate) Monitor for an increase in tamsulosin-related adverse reactions if coadministration with everolimus is necessary. Tamsulosin is a CYP3A4 and CYP2D6 substrate. Everolimus is a weak CYP3A4 inhibitor and a CYP2D6 inhibitor. The effects of coadministration of both a CYP3A4 and CYP2D6 inhibitor with tamsulosin have not been evaluated; however, there is a potential for significantly increased plasma concentrations of tamsulosin.
Fedratinib: (Moderate) Use caution if coadministration of fedratinib with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP3A4 and CYP2D6 substrate and fedratinib is a moderate CYP3A4 and CYP2D6 inhibitor. The effects of concomitant administration of moderate CYP3A4 and moderate CYP2D6 inhibitors on the pharmacokinetics of tamsulosin have not been evaluated, but tamsulosin exposure may increase based on the effects of strong CYP3A4 and CYP2D6 inhibition.
Felodipine: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Finasteride; Tadalafil: (Moderate) Due to the potential for symptomatic hypotension, patients should be stable on tamsulosin therapy before initiating therapy with the lowest recommended dose of tadalafil. Conversely, patients already receiving an optimized dose of tadalafil should be started on the lowest dose of tamsulosin; increases in the alpha-blocker dose should be done in a stepwise fashion. When tadalafil is used for benign prostatic hypertrophy (BPH), discontinue tamsulosin therapy at least 1 day prior to initiating tadalafil therapy. Other variables, such as intravascular volume depletion, concurrent antihypertensive therapy, or evidence of hemodynamic instability with alpha-blocker monotherapy, may affect the safety of concomitant use of tadalafil and tamsulosin.
Fluconazole: (Moderate) Dutasteride is metabolized by the CYP3A4/5 hepatic enzyme. The clearance of dutasteride may be reduced when co-administered with CYP3A4 inhibitors including fluconazole. (Moderate) Use caution if coadministration of fluconazole with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP3A substrate and fluconazole is a moderate CYP3A inhibitor.
Fluoxetine: (Moderate) Use caution if coadministration of fluoxetine with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant treatment with another strong CYP2D6 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 1.3 and 1.6, respectively.
Fluvoxamine: (Moderate) Tamsulosin should be used with caution in combination with moderate inhibitors of CYP3A4 such as fluvoxamine. The cytochrome P450 enzymes CYP3A4 and CYP2D6 are responsible for the extensive metabolism of tamsulosin. Strong inhibitors of CYP3A4 are known to increase the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively. No studies have been performed with moderate CYP3A4 inhibitors. As with other alpha adrenergic blocking agents there is a potential risk of syncope with tamsulosin, particularly if serum concentrations are elevated. Monitor blood pressure and observe for symptoms of orthostasis.
Fosamprenavir: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of anti-retroviral protease inhibitors. Tamsulosin is extensively metabolized by CYP3A4 and CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use of tamsulosin with a strong CYP3A4 inhibitor, or an agent with both CYP3A4 and CYP2D6 inhibitor activity, should be avoided. (Moderate) Concurrent administration of dutasteride with protease inhibitors may result in elevated dutasteride plasma concentrations. Dutasteride is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Grapefruit juice: (Moderate) Hepatic cytochrome P450 enzymes 2D6 and 3A4 are responsible for the extensive metabolism of tamsulosin. Although no clinical studies have been done, tamsulosin should be used with caution with inhibitors of CYP3A4 isoenzymes (e.g., grapefruit juice).
Haloperidol: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as haloperidol. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Idelalisib: (Major) Avoid concomitant use of idelalisib, a strong CYP3A inhibitor, with tamsulosin, a CYP3A substrate, as tamsulosin toxicities may be significantly increased. The AUC of a sensitive CYP3A substrate was increased 5.4-fold when coadministered with idelalisib. (Moderate) Monitor for common side effects of dutasteride, such as libido decrease, breast tenderness, or erectile dysfunction when chronic, potent inhibitors of CYP3A4 like idelalisib are used concomitantly. The effect of potent CYP3A4 inhibitors on the metabolism of dutasteride has not been studied. However, because dutasteride is metabolized by CYP3A4 and CYP3A5 isoenzymes, chronic coadministration with potent CYP3A4 enzyme inhibitors may result in elevated concentrations of dutasteride.
Iloprost: (Minor) Iloprost can have additive effects when administered with other antihypertensive agents, including alpha-blockers. These effects can be used to therapeutic advantage, but dosage adjustments may be necessary.
Imatinib: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of imatinib, STI-571. Tamsulosin is extensively metabolized by CYP2D6 and CYP3A4 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Therefore, concomitant use with drugs that inhibit both CYP2D6 and CYP3A4, such as imatinib, STI-571, should be avoided. (Moderate) Monitor for common side effects of dutasteride, such as libido decrease, breast tenderness, or erectile dysfunction when chronic, potent inhibitors of CYP3A4 like imatinib are used concomitantly. The effect of potent CYP3A4 inhibitors on the metabolism of dutasteride has not been studied. However, because dutasteride is metabolized by CYP3A4 and CYP3A5 isoenzymes, chronic coadministration with potent CYP3A4 enzyme inhibitors may result in elevated concentrations of dutasteride.
Indinavir: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of anti-retroviral protease inhibitors. Tamsulosin is extensively metabolized by CYP3A4 and CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use of tamsulosin with a strong CYP3A4 inhibitor, or an agent with both CYP3A4 and CYP2D6 inhibitor activity, should be avoided. (Moderate) Concurrent administration of dutasteride with protease inhibitors may result in elevated dutasteride plasma concentrations. Dutasteride is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Isavuconazonium: (Moderate) The plasma concentrations of tamsulosin may be elevated when administered concurrently with isavuconazonium. Clinical monitoring for adverse effects, such as hypotension, is recommended during coadministration. Tamsulosin is a substrate of the hepatic isoenzyme CYP3A4 and drug transporter P-glycoprotein (P-gp); isavuconazole, the active moiety of isavuconazonium, is an inhibitor of CYP3A4 and P-gp.
Isradipine: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Itraconazole: (Major) Use of tamsulosin is not recommended during and for 2 weeks after itraconazole therapy due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Tamsulosin is extensively metabolized by CYP3A4 hepatic enzymes, and strong inhibitors of CYP3A4 are expected to significantly raise tamsulosin concentrations. Concomitant treatment with another strong CYP3A4 inhibitor resulted in an increase in the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively. (Moderate) Monitor for increased dutasteride adverse effects if coadministration of itraconazole is necessary. No clinical drug interaction trials have been performed to evaluate the impact of CYP3A enzyme inhibitors on dutasteride pharmacokinetics. However, based on in vitro data, blood concentrations of dutasteride may increase in the presence of inhibitors of CYP3A4 such as itraconazole.
Ketoconazole: (Major) Concurrent use of tamsulosin and ketoconazole is not recommended due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations are expected to produce clinically significant and potentially serious side effects, such as hypotension, dizziness, and vertigo. Tamsulosin is extensively metabolized by CYP3A4. Coadministration with ketoconazole, a strong CYP3A4 inhibitor, increased the Cmax and AUC of tamsulosin 2.2 and 2.8-fold, respectively. (Moderate) Monitor for dutasteride-related adverse reactions if coadministration with ketoconazole is necessary due to a potential for increased dutasteride exposure. Dutasteride is extensively metabolized in humans by CYP3A4/3A5 isoenzymes. The effect of potent CYP3A4 inhibitors on dutasteride has not been studied. Because of the potential for drug-drug interactions, use caution when prescribing dutasteride to patients taking potent, chronic CYP3A4 enzyme inhibitors like ketoconazole, a strong CYP3A4 inhibitor.
Labetalol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Lansoprazole; Amoxicillin; Clarithromycin: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of clarithromycin. Tamsulosin is extensively metabolized by CYP3A4 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use with a strong CYP3A4 inhibitor, such as clarithromycin, should be avoided.
Lefamulin: (Moderate) Use caution if coadministration of oral lefamulin with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP3A4 substrate and oral lefamulin is a moderate CYP3A4 inhibitor; an interaction is not expected with intravenous lefamulin. The effects of concomitant administration of a moderate CYP3A4 inhibitor on the pharmacokinetics of tamsulosin have not been evaluated, but tamsulosin exposure may increase based on the effects of strong CYP3A4 inhibition.
Lenacapavir: (Moderate) Use caution if coadministration of lenacapavir with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP3A substrate and lenacapavir is a moderate CYP3A inhibitor.
Letermovir: (Moderate) An increase in the plasma concentration of dutasteride may occur if given with letermovir. In patients who are also receiving treatment with cyclosporine, the magnitude of this interaction may be amplified. Dutasteride is extensively metabolized by CYP3A4. Letermovir is a moderate CYP3A4 inhibitor; however, when given with cyclosporine, the combined effect on CYP3A4 substrates is similar to a strong CYP3A4 inhibitor. The effects of strong CYP3A4 inhibitors on dutasteride have not been evaluated. (Moderate) An increase in the plasma concentration of tamsulosin may occur when given with letermovir. Avoid this combination in patients who are also receiving treatment with cyclosporine because the magnitude of this interaction may be amplified. Tamsulosin is partially metabolized by CYP3A4. Letermovir is a moderate CYP3A4 inhibitor; however, when given with cyclosporine, the combined effect on CYP3A4 substrates is similar to a strong CYP3A4 inhibitor. In a drug interaction study, concomitant use of tamsulosin with another strong CYP3A4 inhibitor resulted in increase in the maximum plasma concentration and exposure of tamsulosin by a factor of 2.2 and 2.8, respectively. The effects of concurrent use with moderate CYP3A4 inhibitors have not been evaluated.
Levamlodipine: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Levobetaxolol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Levobunolol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Levoketoconazole: (Major) Concurrent use of tamsulosin and ketoconazole is not recommended due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations are expected to produce clinically significant and potentially serious side effects, such as hypotension, dizziness, and vertigo. Tamsulosin is extensively metabolized by CYP3A4. Coadministration with ketoconazole, a strong CYP3A4 inhibitor, increased the Cmax and AUC of tamsulosin 2.2 and 2.8-fold, respectively. (Moderate) Monitor for dutasteride-related adverse reactions if coadministration with ketoconazole is necessary due to a potential for increased dutasteride exposure. Dutasteride is extensively metabolized in humans by CYP3A4/3A5 isoenzymes. The effect of potent CYP3A4 inhibitors on dutasteride has not been studied. Because of the potential for drug-drug interactions, use caution when prescribing dutasteride to patients taking potent, chronic CYP3A4 enzyme inhibitors like ketoconazole, a strong CYP3A4 inhibitor.
Lonafarnib: (Major) Avoid concurrent use of tamsulosin and lonafarnib due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations may produce clinically significant and potentially serious side effects, such as hypotension, dizziness, and vertigo. Tamsulosin is extensively metabolized by CYP3A4, and strong inhibitors of CYP3A4, such as lonafarnib, are expected to significantly raise tamsulosin concentrations. Concomitant treatment with another strong CYP3A4 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively. (Moderate) Monitor for dutasteride-related adverse reactions if coadministration with lonafarnib is necessary. Dutasteride is a CYP3A4 substrate and lonafarnib is a strong CYP3A4 inhibitor. Although the effect of strong CYP3A4 inhibitors on dutasteride has not been studied, dutasteride exposure may increase.
Lopinavir; Ritonavir: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of anti-retroviral protease inhibitors. Tamsulosin is extensively metabolized by CYP3A4 and CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use of tamsulosin with a strong CYP3A4 inhibitor, or an agent with both CYP3A4 and CYP2D6 inhibitor activity, should be avoided. (Moderate) Concurrent administration of dutasteride with protease inhibitors may result in elevated dutasteride plasma concentrations. Dutasteride is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Metoprolol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Metoprolol; Hydrochlorothiazide, HCTZ: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Mifepristone: (Major) Concurrent use of tamsulosin and mifepristone is not recommended due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension, dizziness, and vertigo. Tamsulosin is extensively metabolized by CYP3A, and strong inhibitors of CYP3A, such as mifepristone, are expected to significantly raise tamsulosin concentrations. Concomitant treatment with another strong CYP3A inhibitor increased the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively.
Mirabegron: (Moderate) The effect of mirabegron on tamsulosin pharmacokinetics was determined in drug interaction studies, there was a lack of pharmacokinetic interaction. However, it is recommended that mirabegron be administered with caution in patients taking other medications in the setting of risks for urinary obstruction because of the risk of urinary retention. This includes caution when used with tamsulosin. In addition, mirabegron is a moderate CYP2D6 inhibitor. Exposure of drugs metabolized by CYP2D6 isoenzymes such as tamsulosin may be increased when co-administered with mirabegron.
Mitotane: (Moderate) Use caution if mitotane and tamsulosin are used concomitantly, and monitor for decreased efficacy of tamsulosin and a possible change in dosage requirements. Mitotane is a strong CYP3A4 inducer and tamsulosin is a CYP3A4 substrate; coadministration may result in decreased plasma concentrations of tamsulosin.
Nadolol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Nebivolol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Nebivolol; Valsartan: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Nefazodone: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of nefazodone. Tamsulosin is extensively metabolized by CYP3A4 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use with a strong CYP3A4 inhibitor, such as nefazodone, should be avoided. (Moderate) Dutasteride is metabolized by CYP3A4 enzyme. The clearance of dutasteride may be reduced when co-administered with CYP3A4 inhibitors including nefazodone.
Nelfinavir: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of anti-retroviral protease inhibitors. Tamsulosin is extensively metabolized by CYP3A4 and CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use of tamsulosin with a strong CYP3A4 inhibitor, or an agent with both CYP3A4 and CYP2D6 inhibitor activity, should be avoided. (Moderate) Concurrent administration of dutasteride with protease inhibitors may result in elevated dutasteride plasma concentrations. Dutasteride is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Nicardipine: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Nifedipine: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Nimodipine: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Nirmatrelvir; Ritonavir: (Major) Consider withholding tamsulosin, if clinically appropriate, during receipt of ritonavir-boosted nirmatrelvir. If this is not feasible, consider using an alternative COVID-19 therapy or reducing the tamsulosin dose for patients receiving a dose of 0.8 mg daily. Coadministration may increase tamsulosin exposure resulting in increased hypotension or orthostasis. Tamsulosin is a CYP3A substrate and nirmatrelvir is a CYP3A inhibitor. (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of anti-retroviral protease inhibitors. Tamsulosin is extensively metabolized by CYP3A4 and CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use of tamsulosin with a strong CYP3A4 inhibitor, or an agent with both CYP3A4 and CYP2D6 inhibitor activity, should be avoided. (Moderate) Concurrent administration of dutasteride with protease inhibitors may result in elevated dutasteride plasma concentrations. Dutasteride is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Nisoldipine: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Olanzapine; Fluoxetine: (Moderate) Use caution if coadministration of fluoxetine with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and fluoxetine is a strong CYP2D6 inhibitor. Concomitant treatment with another strong CYP2D6 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 1.3 and 1.6, respectively.
Olmesartan; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Ombitasvir; Paritaprevir; Ritonavir: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of anti-retroviral protease inhibitors. Tamsulosin is extensively metabolized by CYP3A4 and CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use of tamsulosin with a strong CYP3A4 inhibitor, or an agent with both CYP3A4 and CYP2D6 inhibitor activity, should be avoided. (Moderate) Concurrent administration of dutasteride with protease inhibitors may result in elevated dutasteride plasma concentrations. Dutasteride is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Oritavancin: (Minor) Tamsulosin is metabolized by CYP3A4 and CYP2D6; oritavancin is a weak CYP3A4 and CYP2D6 inducer. Plasma concentrations and efficacy of tamsulosin may be reduced if these drugs are administered concurrently.
Paroxetine: (Moderate) Use caution if coadministration of paroxetine with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and paroxetine is a strong CYP2D6 inhibitor. Concomitant treatment with paroxetine increased the Cmax and AUC of tamsulosin by a factor of 1.3 and 1.6, respectively.
Pazopanib: (Moderate) Pazopanib is a weak inhibitor of CYP3A4. Coadministration of pazopanib and tamsulosin, a CYP3A4 substrate, may cause an increase in systemic concentrations of tamsulosin. Use caution when administering these drugs concomitantly.
Peginterferon Alfa-2b: (Minor) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as peginterferon alfa-2b. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Penbutolol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Perindopril; Amlodipine: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Perphenazine: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as perphenazine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Perphenazine; Amitriptyline: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as perphenazine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Phenoxybenzamine: (Major) Tamsulosin should not be administered in combination with other alpha-blockers. The pharmacokinetic and pharmacodynamic interactions between tamsulosin and other alpha-blockers (used for high blood pressure or for benign prostatic hyperplasia) have not been determined. However, interactions or side effects (dizziness, hypotension, syncope, etc.) may be expected from the duplication of pharmacologic effects.
Phentolamine: (Major) Tamsulosin should not be administered in combination with other alpha-blockers. The pharmacokinetic and pharmacodynamic interactions between tamsulosin and other alpha-blockers (used for high blood pressure or for benign prostatic hyperplasia) have not been determined. However, interactions or side effects (dizziness, hypotension, syncope, etc.) may be expected from the duplication of pharmacologic effects.
Pindolol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Posaconazole: (Major) Tamsulosin is extensively metabolized by CYP3A4 hepatic enzymes, and strong inhibitors of CYP3A4 are expected to significantly raise tamsulosin concentrations. Plasma concentrations of tamsulosin are increased with concomitant use of ketoconazole, a strong inhibitor of CYP3A4. Concomitant treatment with ketoconazole resulted in an increase in the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use with a strong CYP3A4 inhibitor, such as ketoconazole, itraconazole, posaconazole, or voriconazole should be avoided. (Moderate) Monitor for common side effects of dutasteride, such as libido decrease, breast tenderness, or erectile dysfunction when chronic, potent inhibitors of CYP3A4 like posaconazole are used concomitantly. The effect of potent CYP3A4 inhibitors on the metabolism of dutasteride has not been studied. However, because dutasteride is metabolized by CYP3A4 and CYP3A5 isoenzymes, chronic coadministration with potent CYP3A4 enzyme inhibitors may result in elevated concentrations of dutasteride.
Prazosin: (Major) Tamsulosin should not be administered in combination with other alpha-blockers. The pharmacokinetic and pharmacodynamic interactions between tamsulosin and other alpha-blockers (used for high blood pressure or for benign prostatic hyperplasia) have not been determined. However, interactions or side effects (dizziness, hypotension, syncope, etc.) may be expected from the duplication of pharmacologic effects.
Propafenone: (Moderate) Use caution if coadministration of propafenone with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP2D6 substrate and propafenone is a moderate CYP2D6 inhibitor.
Propranolol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Propranolol; Hydrochlorothiazide, HCTZ: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Protease inhibitors: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of anti-retroviral protease inhibitors. Tamsulosin is extensively metabolized by CYP3A4 and CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use of tamsulosin with a strong CYP3A4 inhibitor, or an agent with both CYP3A4 and CYP2D6 inhibitor activity, should be avoided. (Moderate) Concurrent administration of dutasteride with protease inhibitors may result in elevated dutasteride plasma concentrations. Dutasteride is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Quinidine: (Moderate) Use caution when administering tamsulosin with a strong CYP2D6 inhibitor such as quinidine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure. If concomitant use in necessary, monitor patient closely for increased side effects.
Quinine: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of quinine. Tamsulosin is extensively metabolized by CYP2D6 and CYP3A4 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Therefore, concomitant use with drugs that inhibit both CYP2D6 and CYP3A4, such as quinine, should be avoided.
Ranolazine: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of ranolazine. Tamsulosin is extensively metabolized by CYP2D6 and CYP3A4 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Therefore, concomitant use with drugs that inhibit both CYP2D6 and CYP3A4, such as ranolazine, should be avoided.
Ribociclib: (Major) Concurrent use of tamsulosin and ribociclib is not recommended due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension, dizziness, and vertigo. Tamsulosin is extensively metabolized by CYP3A4 hepatic enzymes, and strong inhibitors of CYP3A4 are expected to significantly raise tamsulosin concentrations. Concomitant treatment with another strong CYP3A4 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively. (Moderate) Monitor for an increase in dutasteride-related adverse reactions if coadministration with ribociclib is necessary. Dutasteride is a CYP3A4 substrate and ribociclib is a strong CYP3A4 inhibitor.
Ribociclib; Letrozole: (Major) Concurrent use of tamsulosin and ribociclib is not recommended due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension, dizziness, and vertigo. Tamsulosin is extensively metabolized by CYP3A4 hepatic enzymes, and strong inhibitors of CYP3A4 are expected to significantly raise tamsulosin concentrations. Concomitant treatment with another strong CYP3A4 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively. (Moderate) Monitor for an increase in dutasteride-related adverse reactions if coadministration with ribociclib is necessary. Dutasteride is a CYP3A4 substrate and ribociclib is a strong CYP3A4 inhibitor.
Ritonavir: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of anti-retroviral protease inhibitors. Tamsulosin is extensively metabolized by CYP3A4 and CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use of tamsulosin with a strong CYP3A4 inhibitor, or an agent with both CYP3A4 and CYP2D6 inhibitor activity, should be avoided. (Moderate) Concurrent administration of dutasteride with protease inhibitors may result in elevated dutasteride plasma concentrations. Dutasteride is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Rolapitant: (Major) Use caution if tamsulosin and rolapitant are used concurrently, and monitor for tamsulosin-related adverse effects. Tamsulosin is a CYP2D6 substrate and rolapitant is a moderate CYP2D6 inhibitor; the inhibitory effect of rolapitant lasts for at least 7 days, and may last longer after single dose administration. The Cmax and AUC of another CYP2D6 substrate, dextromethorphan, were increased by 120% and 160%, respectively, on day 1 with rolapitant, and by 180% and 230%, respectively, on day 8 after rolapitant administration.
Saquinavir: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of anti-retroviral protease inhibitors. Tamsulosin is extensively metabolized by CYP3A4 and CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use of tamsulosin with a strong CYP3A4 inhibitor, or an agent with both CYP3A4 and CYP2D6 inhibitor activity, should be avoided. (Moderate) Concurrent administration of dutasteride with protease inhibitors may result in elevated dutasteride plasma concentrations. Dutasteride is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Saw Palmetto, Serenoa repens: (Moderate) Saw palmetto may inhibit 5 alpha-reductase, preventing the conversion of testosterone to dihydrotestosterone. This action is similar to the action of 5-alpha reductase inhibitors, such as dutasteride and finasteride. Co-use is likely to be common by patients, but the effects of co-use are not known. In theory, the effects could be additive, but it is not known if the added effects would be beneficial or harmful. Clinicians should be alert for any unusual effects if patients ingest saw palmetto supplements while taking 5-alpha reductase inhibitors.
Sildenafil: (Moderate) Due to the potential for symptomatic hypotension, patients should be stable on tamsulosin therapy before initiating therapy with the lowest dose of sildenafil. Conversely, patients already receiving an optimized dose of sildenafil should be started on the lowest dose of tamsulosin; increases in the alpha-blocker dose should be done in a stepwise fashion. Other variables, such as intravascular volume depletion, concurrent antihypertensive therapy, or evidence of hemodynamic instability with alpha-blocker monotherapy, may affect the safety of concomitant use of sildenafil and tamsulosin.
Silodosin: (Major) The pharmacodynamic effects of coadministration of silodosin and other alpha-blockers has not been studied. Additive effects on blood pressure or an increased incidence of adverse reactions common to alpha-blocker treatment is possible. Therefore, combined use of silodosin and other alpha-blockers is not recommended.
Simeprevir: (Moderate) Simeprevir, a mild intestinal CYP3A4 inhibitor, may increase the side effects of tamsulosin, which is a CYP3A4 substrate. Monitor patients for adverse effects of tamsulosin, such as hypotension, dizziness, syncope, and vertigo.
Sotalol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Soy Isoflavones: (Minor) Theoretically, because the soy isoflavones appear to inhibit type II 5-alpha-reductase, the soy isoflavones may have additive effects with other 5-alpha reductase inhibitors.
Tadalafil: (Moderate) Due to the potential for symptomatic hypotension, patients should be stable on tamsulosin therapy before initiating therapy with the lowest recommended dose of tadalafil. Conversely, patients already receiving an optimized dose of tadalafil should be started on the lowest dose of tamsulosin; increases in the alpha-blocker dose should be done in a stepwise fashion. When tadalafil is used for benign prostatic hypertrophy (BPH), discontinue tamsulosin therapy at least 1 day prior to initiating tadalafil therapy. Other variables, such as intravascular volume depletion, concurrent antihypertensive therapy, or evidence of hemodynamic instability with alpha-blocker monotherapy, may affect the safety of concomitant use of tadalafil and tamsulosin.
Telmisartan; Amlodipine: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Terazosin: (Major) Tamsulosin should not be administered in combination with other alpha-blockers. The pharmacokinetic and pharmacodynamic interactions between tamsulosin and other alpha-blockers (used for high blood pressure or for benign prostatic hyperplasia) have not been determined. However, interactions or side effects (dizziness, hypotension, syncope, etc.) may be expected from the duplication of pharmacologic effects.
Terbinafine: (Moderate) Use caution when administering tamsulosin with a moderate CYP2D6 inhibitor such as terbinafine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Thioridazine: (Moderate) Use caution when administering tamsulosin with a CYP2D6 inhibitor such as thioridazine. Tamsulosin is extensively metabolized by CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP2D6 inhibitor resulted in increases in tamsulosin exposure; interactions with moderate CYP2D6 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Timolol: (Minor) Tamsulosin did not potentiate the hypotensive effects of atenolol. However, since the symptoms of orthostasis are reported more frequently in tamsulosin-treated vs. placebo patients, there is a potential risk of enhanced hypotensive effects when co-administered with antihypertensive agents
Tipranavir: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of anti-retroviral protease inhibitors. Tamsulosin is extensively metabolized by CYP3A4 and CYP2D6 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use of tamsulosin with a strong CYP3A4 inhibitor, or an agent with both CYP3A4 and CYP2D6 inhibitor activity, should be avoided. (Moderate) Concurrent administration of dutasteride with protease inhibitors may result in elevated dutasteride plasma concentrations. Dutasteride is metabolized by the hepatic isoenzyme CYP3A4; protease inhibitors are potent inhibitors of this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Trandolapril; Verapamil: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Tucatinib: (Major) Concurrent use of tamsulosin and tucatinib is not recommended due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension, dizziness, and vertigo. Tamsulosin is extensively metabolized by CYP3A4, and strong inhibitors of CYP3A4, such as tucatinib, are expected to significantly raise tamsulosin concentrations. Concomitant treatment with another strong CYP3A4 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively. (Moderate) Monitor for dutasteride-related adverse reactions if coadministration with tucatinib is necessary. Dutasteride is a CYP3A4 substrate and tucatinib is a strong CYP3A4 inhibitor. Although the effect of strong CYP3A4 inhibitors on dutasteride has not been studied, dutasteride exposure may increase.
Vardenafil: (Moderate) Due to the potential for symptomatic hypotension, patients should be stable on tamsulosin therapy before initiating therapy with the lowest dose of vardenafil. Conversely, patients already receiving an optimized dose of vardenafil should be started on the lowest dose of tamsulosin; increases in the alpha-blocker dose should be done in a stepwise fashion. Other variables, such as intravascular volume depletion, concurrent antihypertensive therapy, or evidence of hemodynamic instability with alpha-blocker monotherapy, may affect the safety of concomitant use of vardenafil and tamsulosin.
Vemurafenib: (Moderate) Vemurafenib is an inducer of CYP3A4 and decreased plasma concentrations of drugs metabolized by this enzyme, such as tamsulosin, could be expected with concurrent use. Use caution, and monitor therapeutic effects of tamsulosin when coadministered with vemurafenib.
Verapamil: (Moderate) The concomitant administration of tamsulosin with other antihypertensive agents can cause additive hypotensive effects. In addition, diltiazem, nicardipine, and verapamil may increase tamsulosin plasma concentrations via CYP3A4 inhibition. This interaction can be therapeutically advantageous, but dosages must be adjusted accordingly.
Vonoprazan; Amoxicillin; Clarithromycin: (Major) Plasma concentrations of tamsulosin may be increased with concomitant use of clarithromycin. Tamsulosin is extensively metabolized by CYP3A4 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension. Therefore, concomitant use with a strong CYP3A4 inhibitor, such as clarithromycin, should be avoided.
Voriconazole: (Major) Concurrent use of tamsulosin and voriconazole is not recommended due to the potential for elevated tamsulosin concentrations. Such increases in tamsulosin concentrations may be expected to produce clinically significant and potentially serious side effects, such as hypotension, dizziness, and vertigo. Tamsulosin is extensively metabolized by CYP3A4 hepatic enzymes, and strong inhibitors of CYP3A4 are expected to significantly raise tamsulosin concentrations. Concomitant treatment with another strong CYP3A4 inhibitor increased the Cmax and AUC of tamsulosin by a factor of 2.2 and 2.8, respectively. (Moderate) Monitor for dutasteride-related adverse effects (e.g., impotence, decreased libido, breast enlargement) if coadministered with voriconazole. Dutasteride is a CYP3A4 substrate, and voriconazole is a strong CYP3A4 inhibitor. Although the effect of strong CYP3A4 inhibitors on dutasteride has not been defined, dutasteride exposure may increase.
Voxelotor: (Moderate) Use caution if coadministration of voxelotor with tamsulosin is necessary, especially at a tamsulosin dose higher than 0.4 mg, as the systemic exposure of tamsulosin may be increased resulting in increased treatment-related adverse reactions including hypotension, dizziness, and vertigo. Tamsulosin is a CYP3A substrate and voxelotor is a moderate CYP3A inhibitor. The effects of concomitant administration of a moderate CYP3A inhibitor on the pharmacokinetics of tamsulosin have not been evaluated, but tamsulosin exposure may increase based on the effects of strong CYP3A inhibition.
Zafirlukast: (Moderate) Use caution when administering tamsulosin with a moderate CYP3A4 inhibitor such as zafirlukast. Tamsulosin is extensively metabolized by CYP3A4 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure; interactions with moderate CYP3A4 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.
Zileuton: (Moderate) Use caution when administering tamsulosin with a moderate CYP3A4 inhibitor such as zileuton. Tamsulosin is extensively metabolized by CYP3A4 hepatic enzymes. In clinical evaluation, concomitant treatment with a strong CYP3A4 inhibitor resulted in significant increases in tamsulosin exposure; interactions with moderate CYP3A4 inhibitors have not been evaluated. If concomitant use in necessary, monitor patient closely for increased side effects.