CONTRAINDICATIONS / PRECAUTIONS
Hyperphosphatemia
Erdafitinib can cause hyperphosphatemia leading to soft tissue mineralization, cutaneous calcinosis, non-uremic calciphylaxis and vascular calcification. Avoid coadministration with agents that alter serum phosphate levels before the initial dose increase period (days 14 to 21), as this may interfere with the determination of the initial dose of erdafitinib. Monitor phosphate levels monthly for hyperphosphatemia and follow dose modification guidelines when required. In patients with hyperphosphatemia, restrict phosphate intake to 600 mg to 800 mg daily. If serum phosphate is above 7 mg/dL, consider adding an oral phosphate binder until the serum phosphate level returns to less than 5.5 mg/dL. Hyperphosphatemia is a commonly reported adverse reaction in patients treated with erdafitinib, as increases in phosphate levels are a pharmacodynamic effect of erdafitinib.[64064]
Ocular disease, visual disturbance
Use erdafitinib with caution in patients with a history of ocular disease. Erdafitinib can cause ocular disorders, including central serous retinopathy (CSR)/retinal pigment epithelial detachment (RPED) resulting in visual field defect. Dry eye symptoms were also commonly reported; all patients should receive dry eye prophylaxis with ocular demulcents as needed. Perform monthly ophthalmological examinations during the first 4 months of treatment and every 3 months thereafter, and urgently at any time for visual disturbance; examinations should include an assessment of visual acuity, slit lamp examination, fundoscopy, and optical coherence tomography. An interruption of therapy, discontinuation of therapy, or dose reduction may be necessary for ocular adverse reactions.[64064]
Poor metabolizers
Monitor for increased erdafitinib-related adverse reactions in patients who are known or suspected to be poor metabolizers with the CYP2C9*3/*3 genotype; erdafitinib plasma concentrations were predicted to be higher in patients with this genotype.
Pregnancy
Pregnancy should be avoided by females of reproductive potential during erdafitinib treatment and for at least 1 month after the last dose. Although there are no adequately controlled studies in pregnant women, erdafitinib can cause fetal harm or death when administered during pregnancy based on its mechanism of action and animal studies. Women who are pregnant or who become pregnant while receiving erdafitinib should be apprised of the potential hazard to the fetus. In an embryo-fetal toxicity study, oral administration of erdafitinib to pregnant rats during organogenesis caused malformations and embryofetal death at less than 0.1% of total human exposures at the maximum recommended human dose based on AUC, including embryo-fetal death, major blood vessel malformations and other vascular anomalies, limb malformations (e.g., ectrodactyly, absent or misshapen long bones), an increased incidence of skeletal anomalies in multiple bones (e.g., vertebrae, sternebrae, ribs), and decreased fetal weight.
Contraception requirements, infertility, male-mediated teratogenicity, pregnancy testing, reproductive risk
Counsel patients about the reproductive risk and contraception requirements during erdafitinib treatment. Erdafitinib can be teratogenic if taken by the mother during pregnancy. Females of reproductive potential should avoid pregnancy and use effective contraception during and for 1 month after the last dose of erdafitinib. Due to the risk of male-mediated teratogenicity, men with female partners of reproductive potential should also use effective contraception during treatment and for 1 month after the last dose. Females of reproductive potential should undergo pregnancy testing prior to initiation of erdafitinib. Women who become pregnant while receiving erdafitinib should be apprised of the potential hazard to the fetus. Although there are no data regarding the effect of erdafitinib on human fertility, female infertility has been observed in animal studies.
Breast-feeding
Due to the potential for serious adverse reactions in nursing infants from erdafitinib, advise women to discontinue breast-feeding during treatment and for 1 month after the final dose. It is not known whether erdafitinib is present in human milk, although many drugs are excreted in human milk.
DRUG INTERACTIONS
Adagrasib: (Major) Avoid coadministration of erdafitinib and adagrasib due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If adagrasib is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A and CYP2C9 substrate and adagrasib is a strong CYP3A and moderate CYP2C9 inhibitor. The mean ratio for the AUC of erdafitinib was 134% when coadministered with another strong CYP3A inhibitor.
Alfentanil: (Major) Avoid coadministration of erdafitinib with alfentanil due to the potential for altered plasma concentrations of alfentanil which may lead to loss of activity or increased toxicity of alfentanil. Alfentanil is a sensitive CYP3A4 substrate with a narrow therapeutic range. Erdafitinib is a time dependent inhibitor and inducer of CYP3A4; the effect of erdafitinib on a sensitive CYP3A4 substrate is unknown.
Alogliptin; Metformin: (Moderate) Consider the benefits and risks of concomitant treatment with metformin and erdafitinib. Metformin is a substrate of organic cationic transporter-2 (OCT2). Erdafitinib is an OCT2 inhibitor. Coadministration with OCT2 inhibitors could increase systemic exposure to metformin and increase the risk for lactic acidosis.
Aluminum Hydroxide: (Major) Avoid coadministration of aluminum hydroxide with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Aluminum hydroxide decreases serum phosphate levels. The initial dose increase of erdafitinib on days 14 to 21 is based on serum phosphate levels; changes in serum phosphate levels by aluminum hydroxide may interfere with the determination of this initial dose increase.
Aluminum Hydroxide; Magnesium Carbonate: (Major) Avoid coadministration of aluminum hydroxide with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Aluminum hydroxide decreases serum phosphate levels. The initial dose increase of erdafitinib on days 14 to 21 is based on serum phosphate levels; changes in serum phosphate levels by aluminum hydroxide may interfere with the determination of this initial dose increase.
Aluminum Hydroxide; Magnesium Hydroxide: (Major) Avoid coadministration of aluminum hydroxide with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Aluminum hydroxide decreases serum phosphate levels. The initial dose increase of erdafitinib on days 14 to 21 is based on serum phosphate levels; changes in serum phosphate levels by aluminum hydroxide may interfere with the determination of this initial dose increase.
Aluminum Hydroxide; Magnesium Hydroxide; Simethicone: (Major) Avoid coadministration of aluminum hydroxide with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Aluminum hydroxide decreases serum phosphate levels. The initial dose increase of erdafitinib on days 14 to 21 is based on serum phosphate levels; changes in serum phosphate levels by aluminum hydroxide may interfere with the determination of this initial dose increase.
Aluminum Hydroxide; Magnesium Trisilicate: (Major) Avoid coadministration of aluminum hydroxide with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Aluminum hydroxide decreases serum phosphate levels. The initial dose increase of erdafitinib on days 14 to 21 is based on serum phosphate levels; changes in serum phosphate levels by aluminum hydroxide may interfere with the determination of this initial dose increase.
Amiodarone: (Major) Avoid coadministration of erdafitinib and amiodarone due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If amiodarone is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP2C9 substrate and amiodarone is a moderate CYP2C9 inhibitor.
Amobarbital: (Major) If coadministration of erdafitinib and amobarbital is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If amobarbital must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If amobarbital is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and amobarbital is a moderate CYP3A4 inducer.
Amoxicillin; Clarithromycin; Omeprazole: (Major) Avoid coadministration of erdafitinib and clarithromycin due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If clarithromycin is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and clarithromycin is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Apalutamide: (Major) Avoid coadministration of erdafitinib and apalutamide due to the risk of decreased plasma concentrations of erdafitinib resulting in decreased efficacy. Erdafitinib is a CYP3A4 substrate and apalutamide is a strong CYP3A4 inducer.
Asciminib: (Major) Avoid coadministration of erdafitinib and asciminib 200 mg twice daily due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If asciminib 200 mg twice daily is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP2C9 substrate and asciminib 200 mg twice daily is a moderate CYP2C9 inhibitor. An interaction is not expected with asciminib doses less than 200 mg twice daily.
Aspirin, ASA; Butalbital; Caffeine: (Major) If coadministration of erdafitinib and butalbital is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If butalbital must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If butalbital is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and butalbital is a moderate CYP3A4 inducer.
Aspirin, ASA; Butalbital; Caffeine; Codeine: (Major) If coadministration of erdafitinib and butalbital is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If butalbital must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If butalbital is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and butalbital is a moderate CYP3A4 inducer.
Atazanavir: (Major) Avoid coadministration of erdafitinib and atazanavir due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If atazanavir is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and atazanavir is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Atazanavir; Cobicistat: (Major) Avoid coadministration of erdafitinib and atazanavir due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If atazanavir is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and atazanavir is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor. (Major) Avoid coadministration of erdafitinib and cobicistat due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If cobicistat is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Berotralstat: (Major) Reduce the berotralstat dose to 110 mg PO once daily in patients chronically taking erdafitinib. Concurrent use may increase berotralstat exposure and the risk of adverse effects. Berotralstat is a P-gp substrate and erdafitinib is a P-gp inhibitor. Coadministration with another P-gp inhibitor increased berotralstat exposure by 69%.
Bexarotene: (Major) If coadministration of erdafitinib and bexarotene is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If bexarotene must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If bexarotene is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and bexarotene is a moderate CYP3A4 inducer.
Bosentan: (Major) If coadministration of erdafitinib and bosentan is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If bosentan must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If bosentan is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 and CYP2C9 substrate. Bosentan is a moderate CYP3A4 and CYP2C9 inducer.
Brodalumab: (Major) Avoid coadministration of erdafitinib and brodalumab due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If brodalumab is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP2C9 substrate and brodalumab is a moderate CYP2C9 inhibitor.
Burosumab: (Major) Avoid coadministration of burosumab with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Burosumab increases serum phosphate levels. Erdafitinib causes hyperphosphatemia as a consequence of FGFR inhibition. Changes in serum phosphate levels by burosumab may interfere with the determination of this initial dose increase and may cause additive hyperphosphatemia.
Butabarbital: (Major) If coadministration of erdafitinib and butabarbital is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If butabarbital must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If butabarbital is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and butabarbital is a moderate CYP3A4 inducer.
Butalbital; Acetaminophen: (Major) If coadministration of erdafitinib and butalbital is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If butalbital must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If butalbital is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and butalbital is a moderate CYP3A4 inducer.
Butalbital; Acetaminophen; Caffeine: (Major) If coadministration of erdafitinib and butalbital is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If butalbital must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If butalbital is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and butalbital is a moderate CYP3A4 inducer.
Butalbital; Acetaminophen; Caffeine; Codeine: (Major) If coadministration of erdafitinib and butalbital is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If butalbital must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If butalbital is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and butalbital is a moderate CYP3A4 inducer.
Calcitriol: (Major) Avoid coadministration of calcitriol with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Calcitriol can increase serum phosphate levels. Erdafitinib causes hyperphosphatemia as a consequence of FGFR inhibition; additionally, the initial dose increase of erdafitinib on days 14 to 21 is based on serum phosphate levels. Changes in serum phosphate levels by calcitriol may interfere with the determination of this initial dose increase and may cause additive hyperphosphatemia.
Calcium Acetate: (Major) Avoid coadministration of calcium acetate with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Calcium acetate decreases serum phosphate levels. The initial dose increase of erdafitinib on days 14 to 21 is based on serum phosphate levels; changes in serum phosphate levels by calcium acetate may interfere with the determination of this initial dose increase.
Calcium Carbonate: (Major) Avoid coadministration of calcium carbonate with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Calcium carbonate decreases serum phosphate levels. The initial dose increase of erdafitinib on days 14 to 21 is based on serum phosphate levels; changes in serum phosphate levels by calcium carbonate may interfere with the determination of this initial dose increase.
Calcium Carbonate; Famotidine; Magnesium Hydroxide: (Major) Avoid coadministration of calcium carbonate with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Calcium carbonate decreases serum phosphate levels. The initial dose increase of erdafitinib on days 14 to 21 is based on serum phosphate levels; changes in serum phosphate levels by calcium carbonate may interfere with the determination of this initial dose increase.
Calcium Carbonate; Magnesium Hydroxide: (Major) Avoid coadministration of calcium carbonate with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Calcium carbonate decreases serum phosphate levels. The initial dose increase of erdafitinib on days 14 to 21 is based on serum phosphate levels; changes in serum phosphate levels by calcium carbonate may interfere with the determination of this initial dose increase.
Calcium Carbonate; Magnesium Hydroxide; Simethicone: (Major) Avoid coadministration of calcium carbonate with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Calcium carbonate decreases serum phosphate levels. The initial dose increase of erdafitinib on days 14 to 21 is based on serum phosphate levels; changes in serum phosphate levels by calcium carbonate may interfere with the determination of this initial dose increase.
Calcium Carbonate; Risedronate: (Major) Avoid coadministration of calcium carbonate with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Calcium carbonate decreases serum phosphate levels. The initial dose increase of erdafitinib on days 14 to 21 is based on serum phosphate levels; changes in serum phosphate levels by calcium carbonate may interfere with the determination of this initial dose increase.
Calcium Carbonate; Simethicone: (Major) Avoid coadministration of calcium carbonate with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Calcium carbonate decreases serum phosphate levels. The initial dose increase of erdafitinib on days 14 to 21 is based on serum phosphate levels; changes in serum phosphate levels by calcium carbonate may interfere with the determination of this initial dose increase.
Calcium; Vitamin D: (Major) Avoid coadministration of calcium carbonate with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Calcium carbonate decreases serum phosphate levels. The initial dose increase of erdafitinib on days 14 to 21 is based on serum phosphate levels; changes in serum phosphate levels by calcium carbonate may interfere with the determination of this initial dose increase.
Canagliflozin; Metformin: (Moderate) Consider the benefits and risks of concomitant treatment with metformin and erdafitinib. Metformin is a substrate of organic cationic transporter-2 (OCT2). Erdafitinib is an OCT2 inhibitor. Coadministration with OCT2 inhibitors could increase systemic exposure to metformin and increase the risk for lactic acidosis.
Carbamazepine: (Major) Avoid coadministration of erdafitinib and carbamazepine due to the risk of decreased plasma concentrations of erdafitinib resulting in decreased efficacy. Erdafitinib is a CYP3A4 and CYP2C9 substrate; carbamazepine is a strong CYP3A4 inducer as well as a CYP2C9 inducer.
Cenobamate: (Major) If coadministration of erdafitinib and cenobamate is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate concentrations and tolerability). If cenobamate must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If cenobamate is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and cenobamate is a moderate CYP3A4 inducer.
Ceritinib: (Major) Avoid coadministration of erdafitinib and ceritinib due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If ceritinib is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and ceritinib is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Chloramphenicol: (Major) Avoid coadministration of erdafitinib and chloramphenicol due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If chloramphenicol is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and chloramphenicol is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Cholera Vaccine: (Moderate) Patients receiving immunosuppressant medications may have a diminished response to the live cholera vaccine. When feasible, administer indicated vaccines prior to initiating immunosuppressant medications. Counsel patients receiving immunosuppressant medications about the possibility of a diminished vaccine response and to continue to follow precautions to avoid exposure to cholera bacteria after receiving the vaccine.
Clarithromycin: (Major) Avoid coadministration of erdafitinib and clarithromycin due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If clarithromycin is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and clarithromycin is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Cobicistat: (Major) Avoid coadministration of erdafitinib and cobicistat due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If cobicistat is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Cyclosporine: (Major) Avoid coadministration of cyclosporine with erdafitinib due to the risk of increased plasma concentrations of cyclosporine. If concomitant use is unavoidable, separate erdafitinib administration by at least 6 hours before or after administration of cyclosporine; monitor cyclosporine levels. Cyclosporine is a P-glycoprotein (P-gp) substrate with a narrow therapeutic index and erdafitinib is a P-gp inhibitor.
Dabrafenib: (Major) If coadministration of erdafitinib and dabrafenib is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If dabrafenib must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If dabrafenib is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and dabrafenib is a moderate CYP3A4 inducer.
Dapagliflozin; Metformin: (Moderate) Consider the benefits and risks of concomitant treatment with metformin and erdafitinib. Metformin is a substrate of organic cationic transporter-2 (OCT2). Erdafitinib is an OCT2 inhibitor. Coadministration with OCT2 inhibitors could increase systemic exposure to metformin and increase the risk for lactic acidosis.
Darunavir: (Major) Avoid coadministration of erdafitinib and darunavir due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If darunavir is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and darunavir is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Darunavir; Cobicistat: (Major) Avoid coadministration of erdafitinib and cobicistat due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If cobicistat is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor. (Major) Avoid coadministration of erdafitinib and darunavir due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If darunavir is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and darunavir is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Darunavir; Cobicistat; Emtricitabine; Tenofovir alafenamide: (Major) Avoid coadministration of erdafitinib and cobicistat due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If cobicistat is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor. (Major) Avoid coadministration of erdafitinib and darunavir due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If darunavir is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and darunavir is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Dasabuvir; Ombitasvir; Paritaprevir; Ritonavir: (Major) Avoid coadministration of erdafitinib and ritonavir due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If ritonavir is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Delavirdine: (Major) Avoid coadministration of erdafitinib and delavirdine due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If delavirdine is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and delavirdine is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Dexamethasone: (Major) If coadministration of erdafitinib and dexamethasone is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If dexamethasone must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If dexamethasone is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and dexamethasone is a moderate CYP3A4 inducer.
Digoxin: (Major) Avoid coadministration of digoxin with erdafitinib due to the risk of increased plasma concentrations of digoxin. If concomitant use is unavoidable, separate erdafitinib administration by at least 6 hours before or after administration of digoxin; monitor digoxin levels. Digoxin is a P-glycoprotein (P-gp) substrate with a narrow therapeutic index and erdafitinib is a P-gp inhibitor.
Dihydrotachysterol: (Major) Avoid coadministration of dihydrotachysterol with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Dihydrotachysterol can increase serum phosphate levels. Erdafitinib causes hyperphosphatemia as a consequence of FGFR inhibition. Changes in serum phosphate levels by dihydrotachysterol may interfere with the determination of this initial dose increase and may cause additive hyperphosphatemia.
Dofetilide: (Contraindicated) Coadministration of dofetilide with erdafitinib is contraindicated due to the risk of increased dofetilide exposure which may be associated with QT prolongation. Dofetilide is eliminated in the kidney by cationic secretion. Erdafitinib is an inhibitor of the renal uptake transporter organic cation transporter 2 (OCT2).
Efavirenz: (Major) If coadministration of erdafitinib and efavirenz is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If efavirenz must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If efavirenz is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and efavirenz is a moderate CYP3A4 inducer.
Efavirenz; Emtricitabine; Tenofovir Disoproxil Fumarate: (Major) If coadministration of erdafitinib and efavirenz is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If efavirenz must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If efavirenz is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and efavirenz is a moderate CYP3A4 inducer.
Efavirenz; Lamivudine; Tenofovir Disoproxil Fumarate: (Major) If coadministration of erdafitinib and efavirenz is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If efavirenz must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If efavirenz is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and efavirenz is a moderate CYP3A4 inducer.
Elagolix: (Major) If coadministration of erdafitinib and elagolix is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If elagolix must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If elagolix is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and elagolix is a moderate CYP3A4 inducer.
Elagolix; Estradiol; Norethindrone acetate: (Major) If coadministration of erdafitinib and elagolix is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If elagolix must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If elagolix is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and elagolix is a moderate CYP3A4 inducer.
Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Alafenamide: (Major) Avoid coadministration of erdafitinib and cobicistat due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If cobicistat is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Disoproxil Fumarate: (Major) Avoid coadministration of erdafitinib and cobicistat due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If cobicistat is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and cobicistat is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Empagliflozin; Linagliptin; Metformin: (Moderate) Consider the benefits and risks of concomitant treatment with metformin and erdafitinib. Metformin is a substrate of organic cationic transporter-2 (OCT2). Erdafitinib is an OCT2 inhibitor. Coadministration with OCT2 inhibitors could increase systemic exposure to metformin and increase the risk for lactic acidosis.
Empagliflozin; Metformin: (Moderate) Consider the benefits and risks of concomitant treatment with metformin and erdafitinib. Metformin is a substrate of organic cationic transporter-2 (OCT2). Erdafitinib is an OCT2 inhibitor. Coadministration with OCT2 inhibitors could increase systemic exposure to metformin and increase the risk for lactic acidosis.
Enzalutamide: (Major) Avoid coadministration of erdafitinib and enzalutamide due to the risk of decreased plasma concentrations of erdafitinib resulting in decreased efficacy. Erdafitinib is a CYP3A4 and CYP2C9 substrate; enzalutamide is a strong CYP3A4 inducer as well as a CYP2C9 inducer.
Ertugliflozin; Metformin: (Moderate) Consider the benefits and risks of concomitant treatment with metformin and erdafitinib. Metformin is a substrate of organic cationic transporter-2 (OCT2). Erdafitinib is an OCT2 inhibitor. Coadministration with OCT2 inhibitors could increase systemic exposure to metformin and increase the risk for lactic acidosis.
Eslicarbazepine: (Major) If coadministration of erdafitinib and eslicarbazepine is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If eslicarbazepine must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If eslicarbazepine is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and eslicarbazepine is a moderate CYP3A4 inducer.
Etravirine: (Major) Avoid coadministration of erdafitinib with etravirine due to an unpredictable effect on erdafitinib plasma concentrations. Erdafitinib is a substrate of CYP2C9 and CYP3A4. Etravirine is an inducer of CYP3A4 and an inhibitor of CYP2C9. The manufacturer of erdafitinib recommends possible dose increases when used with CYP3A4 inducers, and possible dose reductions when used with CYP2C9 inhibitors. Due to the unpredictable effect of etravirine on erdafitinib exposure, an appropriate dose of erdafitinib cannot be recommended.
Everolimus: (Moderate) Monitor everolimus whole blood trough concentrations as appropriate and watch for everolimus-related adverse reactions if coadministration with erdafitinib is necessary. The dose of everolimus may need to be reduced. Everolimus is a P-glycoprotein (P-gp) substrate and erdafitinib is a P-gp inhibitor. Coadministration with P-gp inhibitors may decrease the efflux of everolimus from intestinal cells and increase everolimus blood concentrations.
Fluconazole: (Major) Avoid coadministration of erdafitinib and fluconazole due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If fluconazole is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP2C9 substrate and fluconazole is a moderate CYP2C9 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 121% and 148%, respectively, when coadministered with fluconazole.
Fluorouracil, 5-FU: (Major) Avoid coadministration of erdafitinib and fluorouracil due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If fluorouracil is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP2C9 substrate and fluorouracil is a moderate CYP2C9 inhibitor.
Fosamprenavir: (Major) Avoid coadministration of erdafitinib and fosamprenavir due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If fosamprenavir is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and fosamprenavir is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Fosphenytoin: (Major) Avoid coadministration of erdafitinib and fosphenytoin due to the risk of decreased plasma concentrations of erdafitinib resulting in decreased efficacy. Erdafitinib is a CYP3A4 substrate and fosphenytoin is a strong CYP3A4 inducer.
Glipizide; Metformin: (Moderate) Consider the benefits and risks of concomitant treatment with metformin and erdafitinib. Metformin is a substrate of organic cationic transporter-2 (OCT2). Erdafitinib is an OCT2 inhibitor. Coadministration with OCT2 inhibitors could increase systemic exposure to metformin and increase the risk for lactic acidosis.
Glyburide; Metformin: (Moderate) Consider the benefits and risks of concomitant treatment with metformin and erdafitinib. Metformin is a substrate of organic cationic transporter-2 (OCT2). Erdafitinib is an OCT2 inhibitor. Coadministration with OCT2 inhibitors could increase systemic exposure to metformin and increase the risk for lactic acidosis.
Grapefruit juice: (Major) Advise patients to avoid grapefruit juice while taking erdafitinib due to increased erdafitinib exposure. Erdafitinib is a substrate of CYP2C9 and CYP3A4. Grapefruit juice is a moderate CYP2C9 inhibitor and a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate; Sodium Biphosphate: (Major) Avoid coadministration of sodium phosphates with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Sodium phosphates increase serum phosphate levels. Erdafitinib causes hyperphosphatemia as a consequence of FGFR inhibition. Changes in serum phosphate levels by sodium phosphate may interfere with the determination of this initial dose increase and may cause additive hyperphosphatemia.
Ibritumomab Tiuxetan: (Major) Avoid coadministration of potassium phosphate with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Potassium phosphate increases serum phosphate levels. Erdafitinib causes hyperphosphatemia as a consequence of FGFR inhibition. Changes in serum phosphate levels by potassium phosphate may interfere with the determination of this initial dose increase and may cause additive hyperphosphatemia. (Major) Avoid coadministration of sodium phosphates with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Sodium phosphates increase serum phosphate levels. Erdafitinib causes hyperphosphatemia as a consequence of FGFR inhibition. Changes in serum phosphate levels by sodium phosphate may interfere with the determination of this initial dose increase and may cause additive hyperphosphatemia.
Idelalisib: (Major) Avoid coadministration of erdafitinib and idelalisib due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If idelalisib is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and idelalisib is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Indinavir: (Major) Avoid coadministration of erdafitinib and indinavir due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If indinavir is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and indinavir is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Iron Sucrose, Sucroferric Oxyhydroxide: (Major) Avoid coadministration of iron sucrose; sucroferric oxyhydroxide with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Iron sucrose; sucroferric oxyhydroxide decreases serum phosphate levels. The initial dose increase of erdafitinib on days 14 to 21 is based on serum phosphate levels; changes in serum phosphate levels by iron sucrose; sucroferric oxyhydroxide may interfere with the determination of this initial dose increase.
Isoniazid, INH; Pyrazinamide, PZA; Rifampin: (Major) Avoid the concomitant use of erdafitinib and rifampin due to the risk of decreased plasma concentrations of erdafitinib resulting in decreased efficacy. Erdafitinib is a CYP3A4 and CYP2C9 substrate; rifampin is a strong CYP3A4 and CYP2C9 inducer. Simulations suggested that rifampin may significantly decrease erdafitinib Cmax and AUC.
Isoniazid, INH; Rifampin: (Major) Avoid the concomitant use of erdafitinib and rifampin due to the risk of decreased plasma concentrations of erdafitinib resulting in decreased efficacy. Erdafitinib is a CYP3A4 and CYP2C9 substrate; rifampin is a strong CYP3A4 and CYP2C9 inducer. Simulations suggested that rifampin may significantly decrease erdafitinib Cmax and AUC.
Itraconazole: (Major) Avoid the concomitant use of erdafitinib and itraconazole due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If itraconazole is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and itraconazole is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with itraconazole.
Ketoconazole: (Major) Avoid coadministration of erdafitinib and ketoconazole due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If ketoconazole is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and ketoconazole is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Lansoprazole; Amoxicillin; Clarithromycin: (Major) Avoid coadministration of erdafitinib and clarithromycin due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If clarithromycin is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and clarithromycin is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Lanthanum Carbonate: (Major) Avoid coadministration of lanthanum carbonate with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Lanthanum carbonate decreases serum phosphate levels. The initial dose increase of erdafitinib on days 14 to 21 is based on serum phosphate levels; changes in serum phosphate levels by lanthanum carbonate may interfere with the determination of this initial dose increase.
Levoketoconazole: (Major) Avoid coadministration of erdafitinib and ketoconazole due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If ketoconazole is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and ketoconazole is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Linagliptin; Metformin: (Moderate) Consider the benefits and risks of concomitant treatment with metformin and erdafitinib. Metformin is a substrate of organic cationic transporter-2 (OCT2). Erdafitinib is an OCT2 inhibitor. Coadministration with OCT2 inhibitors could increase systemic exposure to metformin and increase the risk for lactic acidosis.
Lonafarnib: (Major) Avoid coadministration of erdafitinib and lonafarnib due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If lonafarnib is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and lonafarnib is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Loperamide: (Moderate) Monitor for loperamide-associated adverse reactions, such as CNS effects and cardiac toxicities (i.e., syncope, ventricular tachycardia, QT prolongation, torsade de pointes, cardiac arrest), if coadministered with erdafitinib. Concurrent use may increase loperamide exposure. Loperamide is a P-gp substrate and erdafitinib is a P-gp inhibitor. Coadministration with another P-gp inhibitor increased loperamide plasma concentrations by 2- to 3-fold.
Loperamide; Simethicone: (Moderate) Monitor for loperamide-associated adverse reactions, such as CNS effects and cardiac toxicities (i.e., syncope, ventricular tachycardia, QT prolongation, torsade de pointes, cardiac arrest), if coadministered with erdafitinib. Concurrent use may increase loperamide exposure. Loperamide is a P-gp substrate and erdafitinib is a P-gp inhibitor. Coadministration with another P-gp inhibitor increased loperamide plasma concentrations by 2- to 3-fold.
Lopinavir; Ritonavir: (Major) Avoid coadministration of erdafitinib and ritonavir due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If ritonavir is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Lorlatinib: (Major) If coadministration of erdafitinib and lorlatinib is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If lorlatinib must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If lorlatinib is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and lorlatinib is a moderate CYP3A4 inducer.
Lumacaftor; Ivacaftor: (Major) Avoid coadministration of erdafitinib and lumacaftor; ivacaftor due to the risk of decreased plasma concentrations of erdafitinib resulting in decreased efficacy. Erdafitinib is a CYP3A4 substrate and lumacaftor is a strong CYP3A4 inducer.
Lumacaftor; Ivacaftor: (Major) Avoid coadministration of erdafitinib and lumacaftor; ivacaftor due to the risk of decreased plasma concentrations of erdafitinib resulting in decreased efficacy. Erdafitinib is a CYP3A4 substrate and lumacaftor is a strong CYP3A4 inducer.
Mavacamten: (Major) If coadministration of erdafitinib and mavacamten is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If mavacamten must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If mavacamten is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP2C9 and CYP3A substrate and mavacamten is a moderate CYP2C9 and CYP3A inducer.
Metformin: (Moderate) Consider the benefits and risks of concomitant treatment with metformin and erdafitinib. Metformin is a substrate of organic cationic transporter-2 (OCT2). Erdafitinib is an OCT2 inhibitor. Coadministration with OCT2 inhibitors could increase systemic exposure to metformin and increase the risk for lactic acidosis.
Metformin; Repaglinide: (Moderate) Consider the benefits and risks of concomitant treatment with metformin and erdafitinib. Metformin is a substrate of organic cationic transporter-2 (OCT2). Erdafitinib is an OCT2 inhibitor. Coadministration with OCT2 inhibitors could increase systemic exposure to metformin and increase the risk for lactic acidosis.
Metformin; Rosiglitazone: (Moderate) Consider the benefits and risks of concomitant treatment with metformin and erdafitinib. Metformin is a substrate of organic cationic transporter-2 (OCT2). Erdafitinib is an OCT2 inhibitor. Coadministration with OCT2 inhibitors could increase systemic exposure to metformin and increase the risk for lactic acidosis.
Metformin; Saxagliptin: (Moderate) Consider the benefits and risks of concomitant treatment with metformin and erdafitinib. Metformin is a substrate of organic cationic transporter-2 (OCT2). Erdafitinib is an OCT2 inhibitor. Coadministration with OCT2 inhibitors could increase systemic exposure to metformin and increase the risk for lactic acidosis.
Metformin; Sitagliptin: (Moderate) Consider the benefits and risks of concomitant treatment with metformin and erdafitinib. Metformin is a substrate of organic cationic transporter-2 (OCT2). Erdafitinib is an OCT2 inhibitor. Coadministration with OCT2 inhibitors could increase systemic exposure to metformin and increase the risk for lactic acidosis.
Methenamine; Sodium Acid Phosphate: (Major) Avoid coadministration of sodium phosphates with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Sodium phosphates increase serum phosphate levels. Erdafitinib causes hyperphosphatemia as a consequence of FGFR inhibition. Changes in serum phosphate levels by sodium phosphate may interfere with the determination of this initial dose increase and may cause additive hyperphosphatemia.
Methenamine; Sodium Acid Phosphate; Methylene Blue; Hyoscyamine: (Major) Avoid coadministration of sodium phosphates with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Sodium phosphates increase serum phosphate levels. Erdafitinib causes hyperphosphatemia as a consequence of FGFR inhibition. Changes in serum phosphate levels by sodium phosphate may interfere with the determination of this initial dose increase and may cause additive hyperphosphatemia.
Methohexital: (Major) If coadministration of erdafitinib and methohexital is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If methohexital must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If methohexital is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and methohexital is a moderate CYP3A4 inducer.
Mifepristone: (Major) Avoid coadministration of erdafitinib and chronic mifepristone therapy due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If mifepristone is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a substrate of CYP3A4 and CYP2C9. Mifepristone is a moderate CYP2C9 inhibitor and a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor. The clinical significance of this interaction with the short-term use of mifepristone for termination of pregnancy is unknown.
Mitotane: (Major) Avoid coadministration of erdafitinib and mitotane due to the risk of decreased plasma concentrations of erdafitinib resulting in decreased efficacy. Erdafitinib is a CYP3A4 substrate and mitotane is a strong CYP3A4 inducer.
Modafinil: (Major) If coadministration of erdafitinib and modafinil is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If modafinil must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If modafinil is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and modafinil is a moderate CYP3A4 inducer.
Nafcillin: (Major) If coadministration of erdafitinib and nafcillin is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If nafcillin must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If nafcillin is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and nafcillin is a moderate CYP3A4 inducer.
Nanoparticle Albumin-Bound Sirolimus: (Major) Avoid coadministration of sirolimus with erdafitinib as concurrent use may increase sirolimus exposure and risk of toxicity. Alternative agents with lesser interaction potential with sirolimus should be considered. Sirolimus is a P-gp substrate and erdafitinib is a P-gp inhibitor.
Nefazodone: (Major) Avoid coadministration of erdafitinib and nefazodone due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If nefazodone is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and nefazodone is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Nelfinavir: (Major) Avoid coadministration of erdafitinib and nelfinavir due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If nelfinavir is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and nelfinavir is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Nirmatrelvir; Ritonavir: (Major) Avoid coadministration of erdafitinib and ritonavir due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If ritonavir is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Ombitasvir; Paritaprevir; Ritonavir: (Major) Avoid coadministration of erdafitinib and ritonavir due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If ritonavir is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Omeprazole; Amoxicillin; Rifabutin: (Major) If coadministration of erdafitinib and rifabutin is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If rifabutin must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If rifabutin is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer.
Pentobarbital: (Major) If coadministration of erdafitinib and pentobarbital is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If pentobarbital must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If pentobarbital is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and pentobarbital is a moderate CYP3A4 inducer.
Pexidartinib: (Major) If coadministration of erdafitinib and pexidartinib is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If pexidartinib must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If pexidartinib is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and pexidartinib is a moderate CYP3A4 inducer.
Phenobarbital: (Major) Avoid coadministration of erdafitinib and phenobarbital due to the risk of decreased plasma concentrations of erdafitinib resulting in decreased efficacy. Erdafitinib is a CYP3A4 substrate and phenobarbital is a strong CYP3A4 inducer.
Phenobarbital; Hyoscyamine; Atropine; Scopolamine: (Major) Avoid coadministration of erdafitinib and phenobarbital due to the risk of decreased plasma concentrations of erdafitinib resulting in decreased efficacy. Erdafitinib is a CYP3A4 substrate and phenobarbital is a strong CYP3A4 inducer.
Phenytoin: (Major) Avoid coadministration of erdafitinib and phenytoin due to the risk of decreased plasma concentrations of erdafitinib resulting in decreased efficacy. Erdafitinib is a CYP3A4 substrate and phenytoin is a strong CYP3A4 inducer.
Pioglitazone; Metformin: (Moderate) Consider the benefits and risks of concomitant treatment with metformin and erdafitinib. Metformin is a substrate of organic cationic transporter-2 (OCT2). Erdafitinib is an OCT2 inhibitor. Coadministration with OCT2 inhibitors could increase systemic exposure to metformin and increase the risk for lactic acidosis.
Posaconazole: (Major) Avoid coadministration of erdafitinib and posaconazole due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If posaconazole is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and posaconazole is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Potassium Phosphate: (Major) Avoid coadministration of potassium phosphate with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Potassium phosphate increases serum phosphate levels. Erdafitinib causes hyperphosphatemia as a consequence of FGFR inhibition. Changes in serum phosphate levels by potassium phosphate may interfere with the determination of this initial dose increase and may cause additive hyperphosphatemia.
Potassium Phosphate; Sodium Phosphate: (Major) Avoid coadministration of potassium phosphate with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Potassium phosphate increases serum phosphate levels. Erdafitinib causes hyperphosphatemia as a consequence of FGFR inhibition. Changes in serum phosphate levels by potassium phosphate may interfere with the determination of this initial dose increase and may cause additive hyperphosphatemia. (Major) Avoid coadministration of sodium phosphates with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Sodium phosphates increase serum phosphate levels. Erdafitinib causes hyperphosphatemia as a consequence of FGFR inhibition. Changes in serum phosphate levels by sodium phosphate may interfere with the determination of this initial dose increase and may cause additive hyperphosphatemia.
Primidone: (Major) Avoid coadministration of erdafitinib and primidone due to the risk of decreased plasma concentrations of erdafitinib resulting in decreased efficacy. Erdafitinib is a CYP3A4 substrate and primidone is a strong CYP3A4 inducer.
Relugolix: (Major) Avoid concomitant use of relugolix and oral erdafitinib. Concomitant use may increase relugolix exposure and the risk of relugolix-related adverse effects. If concomitant use is unavoidable, administer erdafitinib at least 6 hours after relugolix and monitor for adverse reactions. Relugolix is a P-gp substrate and erdafitinib is a P-gp inhibitor.
Relugolix; Estradiol; Norethindrone acetate: (Major) Avoid concomitant use of relugolix and oral erdafitinib. Concomitant use may increase relugolix exposure and the risk of relugolix-related adverse effects. If concomitant use is unavoidable, administer erdafitinib at least 6 hours after relugolix and monitor for adverse reactions. Relugolix is a P-gp substrate and erdafitinib is a P-gp inhibitor.
Ribociclib: (Major) Avoid coadministration of erdafitinib and ribociclib due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If ribociclib is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and ribociclib is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Ribociclib; Letrozole: (Major) Avoid coadministration of erdafitinib and ribociclib due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If ribociclib is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and ribociclib is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Rifabutin: (Major) If coadministration of erdafitinib and rifabutin is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If rifabutin must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If rifabutin is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and rifabutin is a moderate CYP3A4 inducer.
Rifampin: (Major) Avoid the concomitant use of erdafitinib and rifampin due to the risk of decreased plasma concentrations of erdafitinib resulting in decreased efficacy. Erdafitinib is a CYP3A4 and CYP2C9 substrate; rifampin is a strong CYP3A4 and CYP2C9 inducer. Simulations suggested that rifampin may significantly decrease erdafitinib Cmax and AUC.
Rifapentine: (Major) Avoid coadministration of erdafitinib and rifapentine due to the risk of decreased plasma concentrations of erdafitinib resulting in decreased efficacy. Erdafitinib is a CYP3A4 and CYP2C9 substrate and rifapentine is a strong CYP3A4 inducer and moderate CYP2C9 inducer.
Rifaximin: (Moderate) Monitor for an increase in rifaximin-related adverse reactions if coadministration with erdafitinib is necessary. Concomitant use may increase rifaximin exposure. In patients with hepatic impairment, a potential additive effect of reduced metabolism may further increase systemic rifaximin exposure. Rifaximin is a P-gp substrate and erdafitinib is a P-gp inhibitor. Coadministration with another P-gp inhibitor increased rifaximin overall exposure by 124-fold.
Ritonavir: (Major) Avoid coadministration of erdafitinib and ritonavir due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If ritonavir is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and ritonavir is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Saquinavir: (Major) Avoid coadministration of erdafitinib and saquinavir due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If saquinavir is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and saquinavir is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
SARS-CoV-2 (COVID-19) vaccines: (Moderate) Patients receiving immunosuppressant medications may have a diminished response to the SARS-CoV-2 virus vaccine. When feasible, administer indicated vaccines prior to initiating immunosuppressant medications. Counsel patients receiving immunosuppressant medications about the possibility of a diminished vaccine response and to continue to follow precautions to avoid exposure to SARS-CoV-2 virus after receiving the vaccine.
Secobarbital: (Major) If coadministration of erdafitinib and secobarbital is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If secobarbital must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If secobarbital is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and secobarbital is a moderate CYP3A4 inducer.
Sevelamer: (Major) Avoid coadministration of sevelamer with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Sevelamer decreases serum phosphate levels. The initial dose increase of erdafitinib on days 14 to 21 is based on serum phosphate levels; changes in serum phosphate levels by sevelamer may interfere with the determination of this initial dose increase.
Sirolimus: (Major) Avoid coadministration of sirolimus with erdafitinib as concurrent use may increase sirolimus exposure and risk of toxicity. Alternative agents with lesser interaction potential with sirolimus should be considered. Sirolimus is a P-gp substrate and erdafitinib is a P-gp inhibitor.
Sodium Phosphate Monobasic Monohydrate; Sodium Phosphate Dibasic Anhydrous: (Major) Avoid coadministration of sodium phosphates with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Sodium phosphates increase serum phosphate levels. Erdafitinib causes hyperphosphatemia as a consequence of FGFR inhibition. Changes in serum phosphate levels by sodium phosphate may interfere with the determination of this initial dose increase and may cause additive hyperphosphatemia.
Sotorasib: (Major) If coadministration of erdafitinib and sotorasib is necessary at the initiation of erdafitinib therapy, administer the dose of erdafitinib as recommended (8 mg once daily with potential to increase the dose to 9 mg on days 14 to 21 based on phosphate levels and tolerability). If sotorasib must be added to erdafitinib therapy after the initial dose increase period (days 14 to 21), increase the dose of erdafitinib up to 9 mg. If sotorasib is discontinued, continue erdafitinib at the same dose in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and sotorasib is a moderate CYP3A4 inducer.
St. John's Wort, Hypericum perforatum: (Major) Avoid the concomitant use of erdafitinib and St. John's Wort due to the risk of decreased plasma concentrations of erdafitinib resulting in decreased efficacy. Erdafitinib is a CYP3A4 and CYP2C9 substrate; St. John's Wort is a strong CYP3A4 and CYP2C9 inducer.
Sulfamethoxazole; Trimethoprim, SMX-TMP, Cotrimoxazole: (Major) Avoid coadministration of erdafitinib and sulfamethoxazole due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If sulfamethoxazole is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP2C9 substrate and sulfamethoxazole is a moderate CYP2C9 inhibitor.
Tacrolimus: (Major) Avoid coadministration of erdafitinib with tacrolimus due to the potential for altered plasma concentrations of tacrolimus which may lead to loss of activity or increased toxicity of tacrolimus. Tacrolimus is a sensitive CYP3A4 substrate with a narrow therapeutic range. Erdafitinib is a time dependent inhibitor and inducer of CYP3A4; the effect of erdafitinib on a sensitive CYP3A4 substrate is unknown.
Tipranavir: (Major) Avoid coadministration of erdafitinib and tipranavir due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If tipranavir is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and tipranavir is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Tucatinib: (Major) Avoid coadministration of erdafitinib and tucatinib due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If tucatinib is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and tucatinib is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Valproic Acid, Divalproex Sodium: (Major) Avoid coadministration of erdafitinib and valproic acid due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If valproic acid is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP2C9 substrate and valproic acid is a moderate CYP2C9 inhibitor.
Vincristine Liposomal: (Major) Avoid coadministration of sodium phosphates with erdafitinib before the initial dose increase period (days 14 to 21) which is based on serum phosphate levels. Sodium phosphates increase serum phosphate levels. Erdafitinib causes hyperphosphatemia as a consequence of FGFR inhibition. Changes in serum phosphate levels by sodium phosphate may interfere with the determination of this initial dose increase and may cause additive hyperphosphatemia.
Vonoprazan; Amoxicillin; Clarithromycin: (Major) Avoid coadministration of erdafitinib and clarithromycin due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If clarithromycin is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a CYP3A4 substrate and clarithromycin is a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Voriconazole: (Major) Avoid coadministration of erdafitinib and voriconazole due to the risk of increased plasma concentrations of erdafitinib. If concomitant use is unavoidable, closely monitor for erdafitinib-related adverse reactions and consider dose modifications as clinically appropriate. If voriconazole is discontinued, the dose of erdafitinib may be increased in the absence of drug-related toxicity. Erdafitinib is a substrate of CYP2C9 and CYP3A4. Voriconazole is a moderate CYP2C9 inhibitor and a strong CYP3A4 inhibitor. The mean ratios for the Cmax and AUC of erdafitinib were 105% and 134%, respectively, when coadministered with another strong CYP3A4 inhibitor.
Warfarin: (Moderate) Closely monitor the INR and adjust the dose as necessary if warfarin is coadministered with erdafitinib; concurrent use may increase the risk of bleeding or reduce efficacy. Erdafitinib is a time dependent inhibitor and inducer of CYP3A4 and the R-enantiomer is a CYP3A4 substrate. The S-enantiomer of warfarin exhibits 2 to 5 times more anticoagulant activity than the R-enantiomer, but the R-enantiomer generally has a slower clearance.