DRUG INTERACTIONS
Acetaminophen; Diphenhydramine: (Moderate) Doxercalciferol is converted in the liver to its active metabolites. Although not specifically studied, cytochrome P450 enzyme inhibitors including diphenhydramine may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if products containing diphenhydramine are coadministered with doxercalciferol.
Acetaminophen; Propoxyphene: (Moderate) Cytochrome P450 enzyme inhibitors, such as propoxyphene, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Aliskiren; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Aliskiren; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Aluminum Hydroxide: (Moderate) The chronic use of aluminum-containing antacids for hyperphosphatemia in conjunction with vitamin D analogs can lead to increased aluminum concentrations and toxicity. This is of primary significance in patients with chronic renal failure. Aluminum hydroxide may be used as a phosphate binder in patients receiving vitamin D analogs. The serum phosphate, calcium and calculated calcium-phosphate product (serum Ca x PO4) should be monitored closely. After initiating vitamin D analog therapy, the dose of phosphate binders should be decreased to correct persistent mild hypercalcemia or increased to correct persistent mild hyperphosphatemia.
Aluminum Hydroxide; Magnesium Carbonate: (Moderate) The chronic use of aluminum-containing antacids for hyperphosphatemia in conjunction with vitamin D analogs can lead to increased aluminum concentrations and toxicity. This is of primary significance in patients with chronic renal failure. Aluminum hydroxide may be used as a phosphate binder in patients receiving vitamin D analogs. The serum phosphate, calcium and calculated calcium-phosphate product (serum Ca x PO4) should be monitored closely. After initiating vitamin D analog therapy, the dose of phosphate binders should be decreased to correct persistent mild hypercalcemia or increased to correct persistent mild hyperphosphatemia.
Aluminum Hydroxide; Magnesium Hydroxide: (Moderate) Magnesium-containing antacids, such as magnesium hydroxide, should be used cautiously in patients receiving vitamin D analogs. Because vitamin D analogs can increase serum magnesium concentrations, concomitant use should be avoided, if possible, in patients with chronic renal failure. (Moderate) The chronic use of aluminum-containing antacids for hyperphosphatemia in conjunction with vitamin D analogs can lead to increased aluminum concentrations and toxicity. This is of primary significance in patients with chronic renal failure. Aluminum hydroxide may be used as a phosphate binder in patients receiving vitamin D analogs. The serum phosphate, calcium and calculated calcium-phosphate product (serum Ca x PO4) should be monitored closely. After initiating vitamin D analog therapy, the dose of phosphate binders should be decreased to correct persistent mild hypercalcemia or increased to correct persistent mild hyperphosphatemia.
Aluminum Hydroxide; Magnesium Hydroxide; Simethicone: (Moderate) Magnesium-containing antacids, such as magnesium hydroxide, should be used cautiously in patients receiving vitamin D analogs. Because vitamin D analogs can increase serum magnesium concentrations, concomitant use should be avoided, if possible, in patients with chronic renal failure. (Moderate) The chronic use of aluminum-containing antacids for hyperphosphatemia in conjunction with vitamin D analogs can lead to increased aluminum concentrations and toxicity. This is of primary significance in patients with chronic renal failure. Aluminum hydroxide may be used as a phosphate binder in patients receiving vitamin D analogs. The serum phosphate, calcium and calculated calcium-phosphate product (serum Ca x PO4) should be monitored closely. After initiating vitamin D analog therapy, the dose of phosphate binders should be decreased to correct persistent mild hypercalcemia or increased to correct persistent mild hyperphosphatemia.
Aluminum Hydroxide; Magnesium Trisilicate: (Moderate) The chronic use of aluminum-containing antacids for hyperphosphatemia in conjunction with vitamin D analogs can lead to increased aluminum concentrations and toxicity. This is of primary significance in patients with chronic renal failure. Aluminum hydroxide may be used as a phosphate binder in patients receiving vitamin D analogs. The serum phosphate, calcium and calculated calcium-phosphate product (serum Ca x PO4) should be monitored closely. After initiating vitamin D analog therapy, the dose of phosphate binders should be decreased to correct persistent mild hypercalcemia or increased to correct persistent mild hyperphosphatemia.
Amiloride; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Amiodarone: (Moderate) Amiodarone inhibits CYP450 and may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if amiodarone is coadministered with doxercalciferol.
Amlodipine; Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Amobarbital: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as barbiturates, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Amoxicillin; Clarithromycin; Omeprazole: (Moderate) CYP450 enzyme inhibitors, like clarithromycin, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol. (Moderate) Cytochrome P450 enzyme inhibitors, such as omeprazole, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Aprepitant, Fosaprepitant: (Moderate) Aprepitant/fosaprepitant inhibits CYP450 and may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if aprepitant/fosaprepitant is coadministered.
Aspirin, ASA; Butalbital; Caffeine: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as barbiturates, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Aspirin, ASA; Butalbital; Caffeine; Codeine: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as barbiturates, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Aspirin, ASA; Omeprazole: (Moderate) Cytochrome P450 enzyme inhibitors, such as omeprazole, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Atenolol; Chlorthalidone: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Azilsartan; Chlorthalidone: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Barbiturates: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as barbiturates, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Belladonna Alkaloids; Ergotamine; Phenobarbital: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as barbiturates, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Benazepril; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Bendroflumethiazide; Nadolol: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Bismuth Subcitrate Potassium; Metronidazole; Tetracycline: (Moderate) Cytochrome P450 enzyme inhibitors, such as metronidazole, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Bismuth Subsalicylate; Metronidazole; Tetracycline: (Moderate) Cytochrome P450 enzyme inhibitors, such as metronidazole, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Bisoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Bosentan: (Moderate) Hepatic enzyme inducers such as bosentan, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Bupropion: (Moderate) CYP450 enzyme inhibitors, like bupropion, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if cytochrome P450 inhibitors are coadministered with doxercalciferol.
Bupropion; Naltrexone: (Moderate) CYP450 enzyme inhibitors, like bupropion, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if cytochrome P450 inhibitors are coadministered with doxercalciferol.
Burosumab: (Contraindicated) Vitamin D analogs are contraindicated in patients receiving burosumab; discontinue vitamin D analogs 1 week prior to initiation of burosumab.
Butabarbital: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as barbiturates, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Butalbital; Acetaminophen: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as barbiturates, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Butalbital; Acetaminophen; Caffeine: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as barbiturates, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Butalbital; Acetaminophen; Caffeine; Codeine: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as barbiturates, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Calcifediol: (Major) Withhold calcifediol treatment when using other vitamin D analogs, like doxercalciferol, due to the risk of additive toxicity including hypercalcemia, hypercalciuria, and hyperphosphatemia.
Calcitonin: (Moderate) Calcitonin is given to hypercalcemic patients to reduce serum calcium concentrations. For the treatment of hypercalcemia, vitamin D preparations should be avoided. Vitamin D analogs can elevate serum calcium concentrations and antagonize the effects of the calcitonin for this condition. For the treatment of osteoporosis adequate intake of vitamin D is necessary in conjunction with calcitonin. An increase in serum calcium concentrations helps to reduce bone resorption and loss of bone mass, and offsets the effect of calcitonin in lowering serum calcium levels.
Calcitriol: (Major) The use of doxercalciferol with calcitriol is not recommended because of the increased potential for additive effects and toxicity. Due to the possibility of systemic absorption after topical administration of calcitriol, caution may be warranted in patients receiving high doses of doxercalciferol.
Calcium Acetate: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with calcium salts. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and high doses of calcium-containing salts.
Calcium Carbonate: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with calcium salts. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and high doses of calcium-containing salts.
Calcium Carbonate; Famotidine; Magnesium Hydroxide: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with calcium salts. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and high doses of calcium-containing salts.
Calcium Carbonate; Magnesium Hydroxide: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with calcium salts. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and high doses of calcium-containing salts.
Calcium Carbonate; Magnesium Hydroxide; Simethicone: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with calcium salts. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and high doses of calcium-containing salts.
Calcium Carbonate; Risedronate: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with calcium salts. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and high doses of calcium-containing salts.
Calcium Carbonate; Simethicone: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with calcium salts. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and high doses of calcium-containing salts.
Calcium Chloride: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with calcium salts. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and high doses of calcium-containing salts.
Calcium Gluconate: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with calcium salts. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and high doses of calcium-containing salts.
Calcium: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with calcium salts. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and high doses of calcium-containing salts.
Calcium; Vitamin D: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with calcium salts. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and high doses of calcium-containing salts.
Candesartan; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Captopril; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Carbamazepine: (Moderate) Hepatic enzyme inducers such as carbamazepine, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Carbetapentane; Diphenhydramine; Phenylephrine: (Moderate) Doxercalciferol is converted in the liver to its active metabolites. Although not specifically studied, cytochrome P450 enzyme inhibitors including diphenhydramine may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if products containing diphenhydramine are coadministered with doxercalciferol.
Chlorothiazide: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Chlorthalidone: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Chlorthalidone; Clonidine: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Cholestyramine: (Moderate) Administer doxercalciferol at least 1 hour before or 4 to 6 hours after taking cholestyramine. Cholestyramine can decrease the intestinal absorption of fat or fat soluble vitamins including vitamin D analogs, such as oral doxercalciferol.
Chromium: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with calcium salts. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and high doses of calcium-containing salts.
Cimetidine: (Moderate) CYP450 enzyme inhibitors, like cimetidine, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Cinacalcet: (Moderate) CYP450 enzyme inhibitors, like cinacalcet, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Clarithromycin: (Moderate) CYP450 enzyme inhibitors, like clarithromycin, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Clopidogrel: (Moderate) Doxercalciferol is converted in the liver to 1,25-dihydroxyergocalciferol, the major active metabolite, and 1-alpha, 24-dihydroxyvitamin D2, a minor metabolite. Although not specifically studied, cytochrome P450 enzyme inhibitors including clopidogrel may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if clopidogrel is coadministered with doxercalciferol.
Colestipol: (Moderate) Separate administration of doxercalciferol by 1 hour before or 4 hours after a colestipol dose to limit effects on oral absorption. Because it sequesters bile acids, colestipol may interfere with normal fat absorption and thus may reduce absorption of fat-soluble vitamins like doxercalciferol.
Cyclosporine: (Moderate) CYP450 enzyme inhibitors, like cyclosporine, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Danazol: (Moderate) CYP450 enzyme inhibitors, like danazol, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Delavirdine: (Moderate) CYP450 enzyme inhibitors, like delavirdine, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Desogestrel; Ethinyl Estradiol: (Moderate) CYP450 enzyme inhibitors, like ethinyl estradiol, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Dextromethorphan; Diphenhydramine; Phenylephrine: (Moderate) Doxercalciferol is converted in the liver to its active metabolites. Although not specifically studied, cytochrome P450 enzyme inhibitors including diphenhydramine may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if products containing diphenhydramine are coadministered with doxercalciferol.
Dextromethorphan; Quinidine: (Moderate) Cytochrome P450 enzyme inhibitors, such as quinidine, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Digoxin: (Moderate) Doxercalciferol should be administered with caution to patients receiving digoxin. Vitamin D analogs may cause hypercalemia which increases the risk of digitalis toxicity. In patients receiving doxercalciferol and digoxin concurrently, monitor serum calcium frequently and monitor the patient for signs of digitalis toxicity. More frequent monitoring is necessary when initiating or adjusting the dose of doxercalciferol.
Dihydrotachysterol: (Major) The use of dihydrotachysterol with doxercalciferol is not recommended because of the increased potential for additive effects and toxicity.
Diltiazem: (Moderate) CYP450 enzyme inhibitors, like diltiazem, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Diphenhydramine: (Moderate) Doxercalciferol is converted in the liver to its active metabolites. Although not specifically studied, cytochrome P450 enzyme inhibitors including diphenhydramine may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if products containing diphenhydramine are coadministered with doxercalciferol.
Diphenhydramine; Hydrocodone; Phenylephrine: (Moderate) Doxercalciferol is converted in the liver to its active metabolites. Although not specifically studied, cytochrome P450 enzyme inhibitors including diphenhydramine may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if products containing diphenhydramine are coadministered with doxercalciferol.
Diphenhydramine; Ibuprofen: (Moderate) Doxercalciferol is converted in the liver to its active metabolites. Although not specifically studied, cytochrome P450 enzyme inhibitors including diphenhydramine may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if products containing diphenhydramine are coadministered with doxercalciferol.
Diphenhydramine; Naproxen: (Moderate) Doxercalciferol is converted in the liver to its active metabolites. Although not specifically studied, cytochrome P450 enzyme inhibitors including diphenhydramine may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if products containing diphenhydramine are coadministered with doxercalciferol.
Diphenhydramine; Phenylephrine: (Moderate) Doxercalciferol is converted in the liver to its active metabolites. Although not specifically studied, cytochrome P450 enzyme inhibitors including diphenhydramine may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if products containing diphenhydramine are coadministered with doxercalciferol.
Disulfiram: (Moderate) CYP450 enzyme inhibitors, like disulfiram, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Drospirenone; Ethinyl Estradiol: (Moderate) CYP450 enzyme inhibitors, like ethinyl estradiol, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Drospirenone; Ethinyl Estradiol; Levomefolate: (Moderate) CYP450 enzyme inhibitors, like ethinyl estradiol, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Duloxetine: (Moderate) Doxercalciferol is converted in the liver to 1,25-dihydroxyergocalciferol, the major active metabolite, and 1-alpha, 24-dihydroxyvitamin D2, a minor metabolite. Although not specifically studied, cytochrome P450 enzyme inhibitors including duloxetine may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if duloxetine is coadministered with doxercalciferol.
Efavirenz: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers such as efavirenz may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Efavirenz; Emtricitabine; Tenofovir: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers such as efavirenz may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Efavirenz; Lamivudine; Tenofovir Disoproxil Fumarate: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers such as efavirenz may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Enalapril; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Eprosartan; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Erythromycin: (Moderate) CYP450 enzyme inhibitors, like erythromycin, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Erythromycin; Sulfisoxazole: (Moderate) CYP450 enzyme inhibitors, like erythromycin, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Ethinyl Estradiol: (Moderate) CYP450 enzyme inhibitors, like ethinyl estradiol, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Ethinyl Estradiol; Levonorgestrel; Folic Acid; Levomefolate: (Moderate) CYP450 enzyme inhibitors, like ethinyl estradiol, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Ethinyl Estradiol; Norelgestromin: (Moderate) CYP450 enzyme inhibitors, like ethinyl estradiol, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Ethinyl Estradiol; Norethindrone Acetate: (Moderate) CYP450 enzyme inhibitors, like ethinyl estradiol, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Ethinyl Estradiol; Norgestrel: (Moderate) CYP450 enzyme inhibitors, like ethinyl estradiol, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Ethynodiol Diacetate; Ethinyl Estradiol: (Moderate) CYP450 enzyme inhibitors, like ethinyl estradiol, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Etonogestrel; Ethinyl Estradiol: (Moderate) CYP450 enzyme inhibitors, like ethinyl estradiol, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Fluconazole: (Moderate) Cytochrome P450 enzyme inhibitors, such as fluconazole, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Fosinopril; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Gemfibrozil: (Moderate) CYP450 enzyme inhibitors, like gemfibrozil, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Grapefruit juice: (Moderate) Although not specifically studied, cytochrome P450 enzyme inhibitors, such as grapefruit juice, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy.
Haloperidol: (Moderate) Cytochrome P450 enzyme inhibitors, such as haloperidol, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Hetastarch; Dextrose; Electrolytes: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with calcium salts. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and high doses of calcium-containing salts. (Moderate) Magnesium-containing drug products should be used cautiously in patients receiving vitamin D analogs. Because vitamin D analogs can increase serum magnesium concentrations, the combined use of vitamin D analogs and magnesium-containing drug products should be avoided, if possible, in patients with chronic renal failure.
Hydantoins: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers such as phenytoin and fosphenytoin may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol. Phenytoin can decrease the activity of vitamin D by increasing its metabolism. In rare cases, this has caused anticonvulsant-induced rickets and osteomalacia. Vitamin D supplementation or dosage adjustments may be required in patients who are receiving chronic treatment with anticonvulsants.
Hydralazine; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Hydrochlorothiazide, HCTZ; Methyldopa: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Hydrochlorothiazide, HCTZ; Moexipril: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Ibritumomab Tiuxetan: (Major) High intake of phosphates concomitantly with vitamin D analogs may lead to hyperphosphatemia. Dose adjustment of vitamin D analogs may be necessary during coadministration with phosphorus salts. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia.
Imatinib: (Moderate) Cytochrome P450 enzyme inhibitors, such as imatinib, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Irbesartan; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Isoniazid, INH: (Moderate) Cytochrome P450 enzyme inhibitors, such as isoniazid, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Isoniazid, INH; Pyrazinamide, PZA; Rifampin: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as rifampin, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol. (Moderate) Cytochrome P450 enzyme inhibitors, such as isoniazid, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Isoniazid, INH; Rifampin: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as rifampin, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol. (Moderate) Cytochrome P450 enzyme inhibitors, such as isoniazid, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Itraconazole: (Moderate) Cytochrome P450 enzyme inhibitors, such as itraconazole, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Ketoconazole: (Moderate) Cytochrome P450 enzyme inhibitors, such as ketoconazole, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Lansoprazole; Amoxicillin; Clarithromycin: (Moderate) CYP450 enzyme inhibitors, like clarithromycin, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Leflunomide: (Moderate) Cytochrome P450 enzyme inhibitors, such as leflunomide, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Levoketoconazole: (Moderate) Cytochrome P450 enzyme inhibitors, such as ketoconazole, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Levonorgestrel; Ethinyl Estradiol: (Moderate) CYP450 enzyme inhibitors, like ethinyl estradiol, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Levonorgestrel; Ethinyl Estradiol; Ferrous Bisglycinate: (Moderate) CYP450 enzyme inhibitors, like ethinyl estradiol, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Lisinopril; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Losartan; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Magnesium Citrate: (Moderate) Magnesium-containing drug products, such as magnesium citrate, should be used cautiously in patients receiving vitamin D analogs. Because vitamin D analogs can increase serum magnesium concentrations, the combined use of vitamin D analogs and magnesium-containing drug products should be avoided, if possible, in patients with chronic renal failure.
Magnesium Hydroxide: (Moderate) Magnesium-containing antacids, such as magnesium hydroxide, should be used cautiously in patients receiving vitamin D analogs. Because vitamin D analogs can increase serum magnesium concentrations, concomitant use should be avoided, if possible, in patients with chronic renal failure.
Magnesium Salts: (Moderate) Magnesium-containing drug products should be used cautiously in patients receiving vitamin D analogs. Because vitamin D analogs can increase serum magnesium concentrations, the combined use of vitamin D analogs and magnesium-containing drug products should be avoided, if possible, in patients with chronic renal failure.
Magnesium: (Moderate) Magnesium-containing drug products should be used cautiously in patients receiving vitamin D analogs. Because vitamin D analogs can increase serum magnesium concentrations, the combined use of vitamin D analogs and magnesium-containing drug products should be avoided, if possible, in patients with chronic renal failure.
Mephobarbital: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as barbiturates, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Methohexital: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as barbiturates, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Methyclothiazide: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Metolazone: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Metoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Metronidazole: (Moderate) Cytochrome P450 enzyme inhibitors, such as metronidazole, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Mifepristone: (Moderate) Cytochrome P450 enzyme inhibitors, such as mifepristone, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Mineral Oil: (Moderate) Separate administration of oral vitamin D analogs by 1 hour before or 4 to 6 hours after mineral oil to limit effects on absorption and availability of the vitamin D analog. Absorption of fat-soluble vitamins may be decreased with concomitant administration of mineral oil. The bioavailability of orally administered vitamin D analogs may also be decreased.
Modafinil: (Moderate) Cytochrome P450 enzyme inhibitors, such as modafinil, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Nevirapine: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as nevirapine, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Norethindrone Acetate; Ethinyl Estradiol; Ferrous fumarate: (Moderate) CYP450 enzyme inhibitors, like ethinyl estradiol, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Norethindrone; Ethinyl Estradiol: (Moderate) CYP450 enzyme inhibitors, like ethinyl estradiol, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Norethindrone; Ethinyl Estradiol; Ferrous fumarate: (Moderate) CYP450 enzyme inhibitors, like ethinyl estradiol, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Norgestimate; Ethinyl Estradiol: (Moderate) CYP450 enzyme inhibitors, like ethinyl estradiol, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Olmesartan; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Olmesartan; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Omeprazole: (Moderate) Cytochrome P450 enzyme inhibitors, such as omeprazole, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Omeprazole; Amoxicillin; Rifabutin: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as rifabutin, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol. (Moderate) Cytochrome P450 enzyme inhibitors, such as omeprazole, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Omeprazole; Sodium Bicarbonate: (Moderate) Cytochrome P450 enzyme inhibitors, such as omeprazole, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Orlistat: (Moderate) Orlistat reduced the absorption of fat-soluble vitamins absorption during clinical trials. The bioavailability of orally administered vitamin D analogs may also be decreased. In patients receiving orally-administered vitamin D analogs along with orlistat, close monitoring is recommended. In addition, the manufacturer recommends that fat-soluble vitamin analogs be administered at least 2 hours before or after the administration of orlistat to limit effects on oral absorption.
Paricalcitol: (Major) The use of doxercalciferol with paricalcitol is not recommended because of the increased potential for additive effects and toxicity.
Pentobarbital: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as barbiturates, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Phenicol Derivatives: (Moderate) CYP450 enzyme inhibitors, like chloramphenicol, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Phenobarbital: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as barbiturates, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Phenobarbital; Hyoscyamine; Atropine; Scopolamine: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as barbiturates, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Phosphorated Carbohydrate Solution: (Major) High intake of phosphates concomitantly with vitamin D analogs may lead to hyperphosphatemia. Dose adjustment of vitamin D analogs may be necessary during coadministration with phosphorus salts. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia.
Phosphorus: (Major) High intake of phosphates concomitantly with vitamin D analogs may lead to hyperphosphatemia. Dose adjustment of vitamin D analogs may be necessary during coadministration with phosphorus salts. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia.
Polycarbophil: (Moderate) The concurrent use of vitamin D analogs, like doxercalciferol with calcium polycarbophil may contribute to vitamin D-induced hypercalcemia. Each 625 mg of calcium polycarbophil contains a substantial amount of calcium (approximately 125 mg).
Potassium Phosphate: (Major) High intake of phosphates concomitantly with vitamin D analogs may lead to hyperphosphatemia. Dose adjustment of vitamin D analogs may be necessary during coadministration with phosphorus salts. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia.
Potassium Phosphate; Sodium Phosphate: (Major) High intake of phosphates concomitantly with vitamin D analogs may lead to hyperphosphatemia. Dose adjustment of vitamin D analogs may be necessary during coadministration with phosphorus salts. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia.
Primidone: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as barbiturates, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Propafenone: (Moderate) Cytochrome P450 enzyme inhibitors, such as propafenone, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Propoxyphene: (Moderate) Cytochrome P450 enzyme inhibitors, such as propoxyphene, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Propranolol; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Protease inhibitors: (Moderate) Protease inhibitors may decrease efficacy of doxercalciferol. Doxercalciferol is converted in the liver to 1,25-dihydroxyergocalciferol, the major active metabolite, and 1-alpha, 24-dihydroxyvitamin D2, a minor metabolite. Although not specifically studied, cytochrome P450 enzyme inhibitors, including protease inhibitors, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if these drugs are administered together.
Pyridoxine, Vitamin B6: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with calcium salts. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and high doses of calcium-containing salts.
Quinapril; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Quinidine: (Moderate) Cytochrome P450 enzyme inhibitors, such as quinidine, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Quinine: (Moderate) Cytochrome P450 enzyme inhibitors, such as quinine, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Ranolazine: (Moderate) Cytochrome P450 enzyme inhibitors, including ranolazine, may inhibit the conversion of doxercalciferol to its active metabolite and result in decreased efficacy of doxercalciferol.
Rifabutin: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as rifabutin, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Rifampin: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as rifampin, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Secobarbital: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as barbiturates, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Segesterone Acetate; Ethinyl Estradiol: (Moderate) CYP450 enzyme inhibitors, like ethinyl estradiol, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if CYP450 inhibitors are coadministered with doxercalciferol.
Selective serotonin reuptake inhibitors: (Moderate) Doxercalciferol is converted in the liver to 1,25-dihydroxyergocalciferol, the major active metabolite, and 1-alpha, 24-dihydroxyvitamin D2, a minor metabolite. Although not specifically studied, cytochrome P450 enzyme inhibitors, including selective serotonin reuptake inhibitors (SSRIs), may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy. Patients should be monitored for a decrease in efficacy if SSRIs are coadministered with doxercalciferol.
Sodium Sulfate; Magnesium Sulfate; Potassium Chloride: (Moderate) Magnesium-containing drug products should be used cautiously in patients receiving vitamin D analogs. Because vitamin D analogs can increase serum magnesium concentrations, the combined use of vitamin D analogs and magnesium-containing drug products should be avoided, if possible, in patients with chronic renal failure.
Spironolactone; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
St. John's Wort, Hypericum perforatum: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as St. John's Wort, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Sulfamethoxazole; Trimethoprim, SMX-TMP, Cotrimoxazole: (Moderate) Cytochrome P450 enzyme inhibitors, such as sulfamethoxazole, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Tacrine: (Moderate) Cytochrome P450 enzyme inhibitors, such as tacrine, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Telmisartan; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Terbinafine: (Moderate) Cytochrome P450 enzyme inhibitors, such as terbinafine, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Thiazide diuretics: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Thiopental: (Moderate) Although these interactions have not been specifically studied, hepatic enzyme inducers, such as barbiturates, may affect the 25-hydroxylation of doxercalciferol and may necessitate dosage adjustments of doxercalciferol.
Thioridazine: (Moderate) Cytochrome P450 enzyme inhibitors, such as thioridazine, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Ticlopidine: (Moderate) Cytochrome P450 enzyme inhibitors, such as ticlopidine, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Trandolapril; Verapamil: (Moderate) Cytochrome P450 enzyme inhibitors, such as verapamil, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Triamterene; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) Dose adjustment of vitamin D analogs may be necessary during coadministration with thiazide diuretics. Additionally, serum calcium concentrations should be monitored frequently. Monitor more frequently in patients with a history of hypercalcemia. Hypercalcemia may be exacerbated by coadministration of vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine.
Verapamil: (Moderate) Cytochrome P450 enzyme inhibitors, such as verapamil, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Voriconazole: (Moderate) Cytochrome P450 enzyme inhibitors, such as voriconazole, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Zafirlukast: (Moderate) Cytochrome P450 enzyme inhibitors, such as zafirlukast, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.
Zileuton: (Moderate) Cytochrome P450 enzyme inhibitors, such as zileuton, may inhibit the 25-hydroxylation of doxercalciferol, thereby decreasing the formation of the active metabolite and thus, decreasing efficacy.