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    Vitamin D Supplements

    DEA CLASS

    OTC, Rx

    DESCRIPTION

    Vitamin involved in calcium and phosphate balance and normal bone growth and mineralization
    Found in fortified milk and cereal products, fish, liver, and egg yolks
    Used for prevention and treatment of vitamin D deficiency and rickets

    COMMON BRAND NAMES

    Calcidol, Calciferol, D-Vita, D3 Vitamin, DECARA, Deltalin, Dialyvite, Dialyvite Vitamin D, Drisdol, Ergo D, Fiber with Vitamin D3 Gummies Gluten-Free, MAXIMUM D3, PureMark Naturals Vitamin D, Replesta, Super Happy SUNSHINE Vitamin D3, Thera-D 2000, Thera-D 4000, Thera-D Rapid Repletion, THERA-D SPORT

    HOW SUPPLIED

    Cholecalciferol/Deltalin/Dialyvite Vitamin D/Drisdol/Ergo D/Ergocalciferol/MAXIMUM D3/Super Happy SUNSHINE Vitamin D3 Oral Cap: 1.25mg, 1000IU, 2000IU, 5000IU, 10000IU, 50000IU
    Cholecalciferol/Dialyvite/Thera-D 2000/Thera-D 4000/Thera-D Rapid Repletion/THERA-D SPORT Oral Tab: 400IU, 1000IU, 2000IU, 4000IU, 5000IU, 50000IU
    Cholecalciferol/Fiber with Vitamin D3 Gummies Gluten-Free Oral Tab Chew: 400IU, 500IU, 1000IU, 2000IU, 5000IU

    DOSAGE & INDICATIONS

    For nutritional supplementation of vitamin D based on recommended dietary reference intakes.
    NOTE: Patients with increased risk for deficiency of vitamin D (e.g., cystic fibrosis and other conditions causing chronic fat malabsorption, patients with chronic kidney disease, patients with HIV, or patients taking certain enzyme-inducing medications, etc.) may require higher supplemental doses than those recommended for healthy individuals to maintain normal vitamin D status. In such persons, 25(OH)D concentrations can be used to guide adequate dietary supplementation.
    Oral dosage
    Adults and Geriatrics 18 to 70 years

    15 mcg/day (600 International Units/day) PO is the RDA for vitamin D in adults and elderly up to 70 years of age.

    Geriatrics older than 70 years

    20 mcg/day (800 International Units/day) PO is the RDA for vitamin D in elderly patients older than 70 years of age.

    Adolescents

    15 mcg/day (600 International Units/day) PO is the RDA for vitamin D in adolescents. The AAP recommends 10 mcg/day (400 International Units/day) PO if the adolescent is not obtaining at least 10 mcg (400 International Units) PO through dietary sources. Dietary sources of vitamin D (e.g., fortified milk, eggs, and other foods) may be included in determining the daily intake.

    Children

    15 mcg/day (600 International Units/day) PO is the RDA for vitamin D in children. The AAP recommends 10 mcg/day (400 International Units/day) PO if the child is consuming less than 1,000 mL/day of vitamin D-fortified milk.

    Infants

    10 mcg/day (400 International Units/day) PO beginning within the first few days of life is considered Adequate Intake (AI). RDAs have not been established for infants. Infants that are exclusively breast-fed without vitamin D supplements are at increased risk for deficiency. Because most exclusively formula-fed infants ingest nearly 1 L/day of formula after the first month of life, they will achieve a vitamin D intake of 10 mcg/day (400 International Units/day). Infants who receive a mixture of human milk and formula should get a vitamin D supplement of 10 mcg/day (400 International Units/day) to ensure the AI value. As infants are weaned from human milk and/or formula, intake of vitamin D-fortified milk should be encouraged to provide at least 10 mcg/day (400 International Units/day) of vitamin D. Vitamin D supplementation should continue until the infant consumes at least 1,000 mL per day (1 quart per day) of vitamin D-fortified milk (Whole milk [cow's milk] is not recommended until after 12 months of age).

    Neonates

    10 mcg/day (400 International Units/day) PO beginning within the first few days of life is considered Adequate Intake (AI). RDAs have not been established for infants. Infants that are exclusively breast-fed without vitamin D supplements are at increased risk for deficiency. Because most exclusively formula-fed infants ingest nearly 1 L/day of formula after the first month of life, they will achieve a vitamin D intake of 10 mcg/day (400 International Units/day). Infants who receive a mixture of human milk and formula should get a vitamin D supplement of 10 mcg/day (400 International Units/day) to ensure the AI value. As infants are weaned from human milk and/or formula, intake of vitamin D-fortified milk should be encouraged to provide at least 10 mcg/day (400 International Units/day) of vitamin D. Vitamin D supplementation should continue until the infant consumes at least 1,000 mL per day (1 quart per day) of vitamin D-fortified milk (Whole milk [cow's milk] is not recommended until after 12 months of age).

    Premature neonates weighing 1.5 kg or more

    10 mcg/day (400 International Units/day) PO is recommended by AAP. The Adequate Intake (AI) recommendation is 10 mcg/day (400 International Units/day) PO. There does not appear to be any benefit to intake of vitamin D doses more than 10 mcg/day (400 International Units/day) in preterm infants.

    Premature neonates weighing less than 1.5 kg

    5 to 10 mcg/day (200 to 400 International Units/day) PO is recommended by AAP. If the infant is receiving less than 10 mcg/day (400 International Units/day), increase the dosage to 10 mcg/day (400 International Units/day) when a weight of more than 1.5 kg is reached and full enteral nutrition is tolerated. The Adequate Intake (AI) recommendation for neonates and infants 0 to 6 months is 10 mcg/day (400 International Units/day) PO; a recommended AI for premature neonates is not specified. Premature infants younger than 32 weeks gestational age and weighing less than 1.25 kg who received a high-mineral containing cow milk-based formula and daily vitamin D supplements of about 10 mcg (400 International Units) maintained normal serum 25-hydroxyvitamin D concentrations. There does not appear to be any benefit to intake of vitamin D doses more than 10 mcg/day (400 International Units/day) in preterm infants.

    For the treatment of vitamin D deficiency.
    NOTE: In adults, the Institute of Medicine (IOM) defines vitamin D deficiency as 25(OH)D concentrations of 30 nmol/L or less (12 ng/mL or less) and vitamin D insufficiency as 25(OH)D concentrations of 30 to 50 nmol/L (12 to less than 20 ng/mL). Generally all persons are sufficient at levels of 50 nmol/L or more (20 ng/mL or more). In pediatric patients, the American Academy of Pediatrics (AAP) and the IOM define vitamin D deficiency as 25(OH)D concentrations of 37.5 nmol/L or less (15 ng/mL or less) and vitamin D insufficiency as 25(OH)D concentrations of 50 nmol/L or less (20 ng/mL or less). In contrast, the Endocrine Society guidelines for adults and pediatric patients define vitamin D insufficiency as 25(OH)D concentrations less than 75 nmol/L (less than 30 ng/mL) and vitamin D deficiency as 25(OH)D concentrations less than 50 nmol/L (less than 20 ng/mL).
    For the treatment of vitamin D deficiency in the general population.
    Oral dosage
    Adults

    1,250 mcg (50,000 International Units) PO once weekly or 150 to 250 mcg (6,000 to 10,000 International Units) PO once daily for at least 8 weeks to achieve a serum vitamin D concentration more than 30 ng/mL, followed by maintenance dose of 37.5 to 50 mcg (1,500 to 2,000 International Units PO) once daily.[62269] [62274] Alternative regimens (with varying durations) include 1,250 mcg (50,000 International Units) PO twice weekly, 1,250 mcg (50,000 International Units) three times weekly, 1,250 mcg (50,000 International Units) PO every 2 weeks, and 2,500 mcg (100,000 International Units) PO once weekly. Individualize dose based on serum vitamin D concentrations.[62269] [62275]

    Children and Adolescents

    50 to 125 mcg (2,000 to 5,000 International Units) PO once daily or 1,250 mcg (50,000 International Units) PO once weekly for at least 6 weeks to achieve a serum vitamin D concentration more than 30 ng/mL, followed by maintenance dose of 15 to 25 mcg (600 to 1,000 International Units) PO once daily. Individualize dose based on serum vitamin D concentrations.   Higher doses (up to 250 mcg/day [10,000 International Units/day] PO) have also been used.

    Infants

    25 to 125 mcg (1,000 to 5,000 International Units) PO once daily or 1,250 mcg (50,000 International Units) PO once weekly for at least 6 weeks to achieve a serum vitamin D concentration more than 30 ng/mL, followed by maintenance dose of 10 to 25 mcg (400 to 1,000 International Units) PO once daily. Individualize dose based on serum vitamin D concentrations.  

    Neonates

    25 to 50 mcg (1,000 to 2,000 International Units) PO once daily or 1,250 mcg (50,000 International Units) PO once weekly for at least 6 weeks to achieve a serum vitamin D concentration more than 30 ng/mL, followed by maintenance dose of 10 to 25 mcg (400 to 1,000 International Units) PO once daily. Individualize dose based on serum vitamin D concentrations.  

    For the treatment of vitamin D deficiency in obese patients, patients with malabsorption syndromes (i.e., inflammatory bowel disease), and patients receiving concomitant medications affecting vitamin D metabolism.
    Oral dosage
    Adults

    Initial doses of 150 to 250 mcg (6,000 to 10,000 International Units) PO once daily (2 to 3 times the usual recommended dose) for several weeks or months to maintain a serum vitamin D concentration more than 30 ng/mL, followed by maintenance therapy of at least 75 to 150 mcg (3,000 to 6,000 International Units) PO once daily.

    Children and Adolescents

    Initial doses of 150 to 250 mcg (6,000 to 10,000 International Units) PO once daily (2 to 3 times the usual recommended dose) for several weeks or months to maintain a serum vitamin D concentration more than 30 ng/mL, followed by maintenance therapy of at least 30 to 75 mcg (1,200 to 3,000 International Units) PO once daily.

    Infants

    Initial doses of 150 to 250 mcg (6,000 to 10,000 International Units) PO once daily (2 to 3 times the usual recommended dose) for several weeks or months to maintain a serum vitamin D concentration more than 30 ng/mL, followed by maintenance therapy of at least 20 to 75 mcg (800 to 3,000 International Units) PO once daily.

    Neonates

    Initial doses of 100 to 150 mcg (4,000 to 6,000 International Units) PO once daily (2 to 3 times the usual recommended dose) for several weeks or months to maintain a serum vitamin D concentration more than 30 ng/mL, followed by maintenance therapy of at least 20 to 75 mcg (800 to 3,000 International Units) PO once daily.

    For the treatment of vitamin D deficiency in cystic fibrosis patients.
    NOTE: Cholecalciferol is recommended over ergocalciferol in patients with cystic fibrosis.
    Oral dosage
    Adults

    Initially, 40 to 150 mcg (1,600 to 6,000 International Units) PO once daily. May increase dose to a maximum of 250 mcg (10,000 International Units) PO once daily to maintain a serum vitamin D concentration of at least 30 ng/mL (75 mmol/L).

    Children and Adolescents 11 to 17 years

    Initially, 40 to 150 mcg (1,600 to 6,000 International Units) PO once daily. May increase dose to a maximum of 250 mcg (10,000 International Units) PO once daily to maintain a serum vitamin D concentration of at least 30 ng/mL (75 mmol/L).

    Children 1 to 10 years

    Initially, 40 to 75 mcg (1,600 to 3,000 International Units) PO once daily. May increase dose to a maximum of 100 mcg (4,000 International Units) PO once daily to maintain a serum vitamin D concentration of at least 30 ng/mL (75 mmol/L).

    Infants

    Initially, 20 to 25 mcg (800 to 1,000 International Units) PO once daily. May increase dose to a maximum of 50 mcg (2,000 International Units) PO once daily to maintain a serum vitamin D concentration of at least 30 ng/mL (75 mmol/L).

    Neonates

    Initially, 20 to 25 mcg (800 to 1,000 International Units) PO once daily. May increase dose to a maximum of 50 mcg (2,000 International Units) PO once daily to maintain a serum vitamin D concentration of at least 30 ng/mL (75 mmol/L).

    For the treatment of nutritional rickets.
    Oral dosage
    Children and Adolescents

    Typical dose ranges are 50 to 500 mcg (2,000 to 20,000 International Units) PO daily for 4 to 8 weeks, with the duration of treatment determined by evidence of radiologic healing. Thereafter, supplement with the RDA to prevent further deficiency. Alternatively, at least 125 mcg (5,000 International Units) PO once daily has also been recommended for initial treatment; weekly regimens (e.g., high doses, such as 1,250 mcg [50,000 International Units] PO once weekly) or a single higher-dose course over 1 to 5 days may be considered if compliance is an issue that prevents adequate repletion. Large single dose regimens (5,000 to 15,000 mcg [200,000 to 600,000 International Units] PO divided into 2 to 4 doses administered over 1 day) have been used when compliance is a concern, but are sometimes controversial due to a purported risk for hypercalcemia. It is important to ensure adequate dietary intake of calcium and phosphorus. Active treatment may continue for 2 to 3 months to replete deficient stores, followed by maintenance dosing with the RDA. Individualize dose based upon 25(OH)D concentrations.

    Infants

    25 to 125 mcg (1,000 to 5,000 International Units) PO once daily has been recommended. Radiologic evidence of healing is usually observed in 2 to 4 weeks, and the active treatment duration is usually 2 to 3 months, after which the supplementation may be reduced to maintenance dosing in accordance with RDAs to prevent further deficiency. Supplementation with calcium is necessary due to the risk of hypocalcemia during bone remineralization. It is important to ensure adequate dietary intake of calcium and phosphorus. Weekly regimens (e.g., high doses, such as 1,250 mcg [50,000 International Units] PO once weekly) have been considered in older infants if compliance is an issue that prevents adequate repletion. Individualize dose based upon 25(OH)D concentrations.

    Neonates

    25 mcg (1,000 International Units) PO once daily has been recommended. Radiologic evidence of healing is usually observed in 2 to 4 weeks, and the active treatment duration is usually 2 to 3 months, after which the supplementation may be reduced to maintenance dosing in accordance with RDAs to prevent further deficiency. Supplementation with calcium is necessary due to the risk of hypocalcemia during bone remineralization. It is important to ensure adequate dietary intake of calcium and phosphorus. Individualize dose based upon 25(OH)D concentrations.

    For the treatment of Hereditary 1,25-Dihydroxyvitamin D Resistant Rickets (HVDRR), also known as hereditary vitamin D resistant rickets type 2.
    Oral dosage
    Children and Adolescents

    Treatment for HVDRR is not standardized. Despite significant improvements in vitamin D concentrations following high-dose ergocalciferol (or use of a vitamin D analog like calcitriol) alone, patients may remain hypocalcemic and hypophosphatemic. High doses of ergocalciferol (vitamin D2) have been used in these patients. The following regimens have been used with variable results: 100 to 1,000 mcg/day (4,000 to 40,000 International Units/day) PO or 5 to 7 mcg/kg/day (200 to 280 International Units/kg/day) PO. However, doses as high as 5,000 mcg/day (200,000 International Units/day) PO have not been effective in improving the disease in other patients. Patients should receive a 3 to 6 month trial of high dose vitamin D along with high-dose calcium therapy. Patients without alopecia appear more likely to respond. The FDA-approved dose is 300 to 12,500 mcg (12,000 to 500,000 International Units) PO daily. Calcium intake should be adequate. Blood calcium and phosphorus determinations are recommended every 2 weeks or more frequently if clinically indicated. X-rays of the bones are recommended every month until condition is corrected and stabilized. Individualize dose based upon 25(OH)D concentrations.

    For osteoporosis prophylaxis and treatment in conjunction with calcium supplementation.
    For osteoporosis prevention in patients receiving corticosteroids.
    Oral dosage
    Adults

    20 mcg (800 International Units) PO daily; different doses may be recommended dependent on concomitant pharmacological treatment or prevention. The American College of Rheumatology recommends supplementation of vitamin D and calcium in all patients receiving corticosteroid therapy, especially if treatment duration will exceed 3 months.

    Children and Adolescents

    20 mcg (800 International Units) PO daily. The American College of Rheumatology recommends supplementation of vitamin D and calcium in all patients receiving corticosteroid therapy, especially if treatment duration will exceed 3 months.

    Oral dosage
    Adults 50 years and older

    20 to 25 mcg (800 to 1,000 international units) PO daily is recommended by the National Osteoporosis Foundation. Supplementation regimen should include calcium for greatest benefit.

    For the treatment of hypoparathyroidism with calcium supplementation.
    Oral Dosage
    Adults

    1,250 to 5,000 mcg (50,000 to 200,000 International Units) PO once daily along with calcium supplements.

    Children and Adolescents

    1,250 to 5,000 mcg (50,000 to 200,000 International Units) PO once daily along with calcium supplements.

    For the treatment of familial hypocholesterolemia (e.g., abetalipoproteinemia, hypobetalipoproteinemia, and chylomicron retention disease, CRD).
    Oral dosage
    Infants, Children, and Adolescents

    20 to 30 mcg (800 to 1,200 International Units) PO daily has been recommended. If Vitamin D supplementation is started early, it prevents development of osteopenia in these patients. Alternative regimens for children 1 to 5 years of age are 2,500 mcg (100,000 International Units) PO once every 2 months; if older than 5 years of age, then 15,000 mcg (600,000 International Units) PO once every 2 months may be used.

    For the prevention of premenstrual syndrome (PMS)†.
    Oral dosage
    Adult females

    A total dose of 17.5 mcg (700 International Units) PO daily from a combination of dietary and non-dietary sources. In a population-based study of 3,025 females, the daily vitamin D and calcium intake was followed to determine if vitamin D or calcium had an impact on the risk of developing PMS. Women with the highest intake of vitamin D from both dietary sources and supplements (median 17.7 mcg [706 International Units daily]) had a reduced risk of developing PMS compared with those women with the lowest intake of vitamin D of 2.8 mcg (112 International Units) daily (RR of 0.59, 95% CI 0.4 to 0.86, p = 0.01 for the trend).[31641]

    For the prevention and treatment of vitamin D deficiency and secondary hyperparathyroidism and resultant bone disease (renal osteodystrophy†) in patients with CKD.
    Oral dosage
    Adults

    1,250 mcg (50,000 International Units) PO once weekly or monthly until target serum total hydroxyvitamin D concentrations are achieved.    Cholecalciferol is more effective at raising serum total 25-hydroxyvitamin D concentrations in non-dialysis-dependent CKD patients (CKD G3a-5) compared with ergocalciferol and may be preferable in these patients.  

    †Indicates off-label use

    MAXIMUM DOSAGE

    NOTE: The Tolerable Upper Intake Level (UL) is defined as the highest daily intake of a nutrient that is likely to pose no risk in otherwise healthy individuals. The ULs are not intended to apply to individuals with specific disease states. Maximum doses for other uses are indication specific.

    Adults

    Maintenance Tolerable Upper Intake Level (UL) is 100 mcg/day (4,000 International Units/day) PO.

    Geriatric

    Maintenance Tolerable Upper Intake Level (UL) is 100 mcg/day (4,000 International Units/day) PO.

    Adolescents

    Maintenance Tolerable Upper Intake Level (UL) is 100 mcg/day (4,000 International Units/day) PO.

    Children

    Children 9 to 12 years: Maintenance Tolerable Upper Intake Level (UL) is 100 mcg/day (4,000 International Units/day) PO.
    Children 4 to 8 years: Maintenance Tolerable Upper Intake Level (UL) is 75 mcg/day (3,000 International Units/day) PO.
    Children 1 to 3 years: Maintenance Tolerable Upper Intake Level (UL) is 62.5 mcg/day (2,500 International Units/day) PO.

    Infants

    Infants 7 to 12 months: Maintenance Tolerable Upper Intake Level (UL) is 37.5 mcg/day (1,500 International Units/day) PO.
    Infants 1 to 6 months: Maintenance Tolerable Upper Intake Level (UL) is 25 mcg/day (1,000 International Units/day) PO.

    Neonates

    Maintenance Tolerable Upper Intake Level (UL) is 25 mcg/day (1,000 International Units/day) PO.

    DOSING CONSIDERATIONS

    Hepatic Impairment

    Specific guidelines for dosage adjustments in hepatic impairment are not available; higher doses may be needed to compensate for reductions in intestinal absorption.

    Renal Impairment

    Specific guidelines for dosage adjustments in renal impairment are not available. However, vitamin D is activated in the kidney; close monitoring is required to ensure the appropriate dose.

    ADMINISTRATION

    Oral Administration

    While vitamin D may be taken without regard to food, it is better absorbed when taken with foods containing fat.

    Oral Liquid Formulations

    Some formulations of vitamin D oral solution/drops contain propylene glycol. When selecting oral liquid preparations for neonates, infants, and young children, ensure the correct formulation of vitamin D is chosen to avoid propylene glycol toxicity.
    Administer using a calibrated measuring device to ensure dosage accuracy. Due to the risk of inadvertently administering an incorrect dose to infants, the FDA recommends using a product with a dropper that will measure no more than 10 mcg (400 International Units) per dose.
    Administer directly into the mouth or mix with breast milk, formula, fruit juice, cereal, or other foods. If mixed, make sure the patient drinks or eats the entire portion to ensure they receive the total amount of the medication.
    Storage: After opening, store away from direct light.

    STORAGE

    Generic:
    - Store in a cool, dry place
    Calcidol:
    - Store between 68 to 77 degrees F, excursions permitted 59 to 86 degrees F
    Calciferol:
    - Store between 68 to 77 degrees F, excursions permitted 59 to 86 degrees F
    D3 Vitamin:
    - Store between 68 to 77 degrees F, excursions permitted 59 to 86 degrees F
    DECARA:
    - Protect from direct sunlight
    - Store at room temperature (between 59 to 86 degrees F)
    - Store in a dry place
    Deltalin:
    - Protect from light
    - Store at controlled room temperature (between 68 and 77 degrees F)
    Dialyvite:
    - Store at room temperature (between 59 to 86 degrees F)
    Dialyvite Vitamin D:
    - Storage information not available
    Drisdol:
    - Store between 68 to 77 degrees F, excursions permitted 59 to 86 degrees F
    D-Vita:
    - Store between 68 to 77 degrees F, excursions permitted 59 to 86 degrees F
    Ergo D:
    - Protect from light
    - Store at controlled room temperature (between 68 and 77 degrees F)
    Fiber with Vitamin D3 Gummies Gluten-Free:
    - Avoid excessive heat (above 104 degrees F)
    - Store at room temperature (between 59 to 86 degrees F)
    MAXIMUM D3:
    - Avoid excessive heat (above 104 degrees F)
    - Store at room temperature (between 59 to 86 degrees F)
    PureMark Naturals Vitamin D:
    - Storage information not listed
    Replesta:
    - Do not store for prolonged periods at extreme temperatures
    - Store at room temperature (up to 77 degrees F)
    Super Happy SUNSHINE Vitamin D3:
    - Store at room temperature
    Thera-D 2000:
    - Store in a cool, dry place
    Thera-D 4000:
    - Protect from heat
    - Protect from moisture
    Thera-D Rapid Repletion:
    - Store in a cool, dry place
    THERA-D SPORT:
    - Store in a cool, dry place

    CONTRAINDICATIONS / PRECAUTIONS

    General Information

     

    Children, hypercalcemia, hypervitaminosis D, infants, neonates, premature neonates, tartrazine dye hypersensitivity

    Vitamin D is contraindicated in patients with hypercalcemia, hypervitaminosis D, and vitamin D hypersensitivity or hypersensitivity to any of the excipients in the formulation. Certain vitamin D formulations contain FD&C yellow dye No. 5 (tartrazine); these formulations should not be used in patients with tartrazine dye hypersensitivity. Hypersensitivity to vitamin D is one etiologic factor in infants with idiopathic hypercalcemia; in these patients, vitamin D intake must be seriously restricted. Some formulations of the oral solution contain propylene glycol. The clinician should be aware of the toxic potential for young children (e.g., neonates and premature neonates, infants, and children younger than 4 years) and ensure the correct formulation of vitamin D is chosen. Excessive propylene glycol can cause lactic acidosis, hyperosmolality, tachypnea, tachycardia, diaphoresis, and central nervous system toxicity (e.g., seizures, intraventricular hemorrhage).

    Renal disease, renal failure

    Patients with renal disease, especially renal failure, may be at increased risk for vitamin D-induced hypercalcemia even with usual dosages. Close clinical monitoring is needed to ensure adequate supplementation and, in pediatric patients, proper growth. In patients with stage 3 or higher kidney disease, use of a vitamin D analog appears preferred, following recommendations of the National Kidney Foundation.

    Biliary tract disease, Crohn's disease, cystic fibrosis, fat malabsorption, gallbladder disease, hepatic disease, malabsorption syndrome

    Vitamin D is contraindicated in patients with malabsorption syndrome. Patients with fat malabsorption due to cystic fibrosis, Crohn's disease, some forms of hepatic disease, gallbladder disease or biliary tract disease may require higher doses of vitamin D due to decreases in intestinal absorption. Some patients taking concurrent medications (e.g., certain anticonvulsants) may require higher doses as well. The prescription of active vitamin D analogs may be preferred in such cases.

    Pregnancy

    Adverse effects have not been reported with the normal daily intake of Vitamin D within the recommended dietary daily intakes for a pregnant female. Animal reproduction studies have shown fetal abnormalities in several species associated with hypervitaminosis D; therefore, the use of vitamin D in excess of the recommended dietary allowance during normal pregnancy should be avoided unless, in the judgment of the physician, potential benefits outweigh the hazards involved. The RDA of vitamin D during pregnancy is 15 mcg/day (600 International Units/day) with a Tolerable Upper Intake Limit of 100 mcg/day (4,000 International Units/day).

    Breast-feeding

    The 25-hydroxyvitamin D metabolite of vitamin D is distributed into human breast milk at concentrations relative to the maternal serum concentration. Typical breast milk concentrations (without maternal supplementation) are not sufficient to prevent vitamin D deficiency in infants that are exclusively breast-fed and do not receive other vitamin D supplementation. Prolonged, exclusive breast-feeding of infants without recommended vitamin D supplementation is a significant cause of rickets in infants, especially in dark-skinned infants breast-fed by mothers who are not vitamin D replete. Use of vitamin D within the recommended daily dietary intake for lactating women is generally recognized as safe. The recommended maternal daily allowance of vitamin D during breast-feeding is 600 International Units/day with a Tolerable Upper Intake Limit of 4000 International Units/day. While high-dose vitamin D supplementation to nursing mothers has been shown to increase the concentration of vitamin D in breast milk and favorably increase 25(OH)D levels in infants, the results have not been validated and supplementation to infants is still recommended. Generally, the serum calcium concentrations of the infant should be monitored when a nursing mother is prescribed vitamin D in high doses, since hypercalcemia has been reported with high dose maternal use.

    ADVERSE REACTIONS

    Severe

    hypervitaminosis D / Delayed / 0-1.0

    Moderate

    constipation / Delayed / 0-1.0
    hypercalciuria / Delayed / 0-1.0
    hypercalcemia / Delayed / 0-1.0
    growth inhibition / Delayed / Incidence not known

    Mild

    headache / Early / 0-1.0
    polydipsia / Early / 0-1.0
    irritability / Delayed / 0-1.0
    nausea / Early / 0-1.0
    fatigue / Early / 0-1.0
    increased urinary frequency / Early / 0-1.0

    DRUG INTERACTIONS

    Abacavir; Dolutegravir; Lamivudine: (Moderate) Administer dolutegravir 2 hours before or 6 hours after taking supplements containing calcium if given under fasting conditions. When taken with food, dolutegravir and supplements containing calcium can be taken at the same time. Simultaneous administration under fasted conditions may result in reduced bioavailability of dolutegravir.
    Acalabrutinib: (Moderate) Separate the administration of acalabrutinib and calcium carbonate by at least 2 hours if these agents are used together; decreased acalabrutinib exposure occurred when acalabrutinib and calcium carbonate were coadministered in a drug interaction study. Acalabrutinib solubility decreases with increasing pH values. In healthy subjects, the AUC of acalabrutinib was decreased by 53% when acalabrutinib was coadministered with calcium carbonate 1 gram.
    Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Acetaminophen; Dextromethorphan; Guaifenesin; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Acetaminophen; Dextromethorphan; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Acetaminophen; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Acrivastine; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Alendronate: (Moderate) Separate administration of alendronate and calcium-containing supplements by at least 30 minutes. Calcium will interfere with the absorption of alendronate.
    Alendronate; Cholecalciferol: (Moderate) Separate administration of alendronate and calcium-containing supplements by at least 30 minutes. Calcium will interfere with the absorption of alendronate.
    Aliskiren; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Aliskiren; Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Aluminum Hydroxide: (Moderate) The chronic use of aluminum-containing antacids (e.g., aluminum hydroxide-containing antacids) for hyperphosphatemia in conjunction with vitamin D can lead to aluminum retention and possible toxicity. This is of primary significance in patients with renal failure.
    Aluminum Hydroxide; Magnesium Carbonate: (Moderate) The chronic use of aluminum-containing antacids (e.g., aluminum hydroxide-containing antacids) for hyperphosphatemia in conjunction with vitamin D can lead to aluminum retention and possible toxicity. This is of primary significance in patients with renal failure.
    Aluminum Hydroxide; Magnesium Hydroxide: (Moderate) Magnesium-containing antacids, such as magnesium hydroxide, should be used cautiously in patients receiving vitamin D (cholecalciferol). Because vitamin D can increase serum magnesium concentrations, the combined use of vitamin D and magnesium-containing drug products should be avoided, if possible, in patients with chronic renal failure. (Moderate) The chronic use of aluminum-containing antacids (e.g., aluminum hydroxide-containing antacids) for hyperphosphatemia in conjunction with vitamin D can lead to aluminum retention and possible toxicity. This is of primary significance in patients with renal failure.
    Aluminum Hydroxide; Magnesium Hydroxide; Simethicone: (Moderate) Magnesium-containing antacids, such as magnesium hydroxide, should be used cautiously in patients receiving vitamin D (cholecalciferol). Because vitamin D can increase serum magnesium concentrations, the combined use of vitamin D and magnesium-containing drug products should be avoided, if possible, in patients with chronic renal failure. (Moderate) The chronic use of aluminum-containing antacids (e.g., aluminum hydroxide-containing antacids) for hyperphosphatemia in conjunction with vitamin D can lead to aluminum retention and possible toxicity. This is of primary significance in patients with renal failure.
    Aluminum Hydroxide; Magnesium Trisilicate: (Moderate) The chronic use of aluminum-containing antacids (e.g., aluminum hydroxide-containing antacids) for hyperphosphatemia in conjunction with vitamin D can lead to aluminum retention and possible toxicity. This is of primary significance in patients with renal failure.
    Amiloride; Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Amlodipine; Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Amphetamine: (Moderate) Calcium carbonate is a gastrointestinal alkalinizing agent that may iincrease the oral absorption of amphetamines and increase amphetamine concentrations. To help limit an interaction, do not take caclium carbonate at the same time as the amphetamine product. It is recommended to separate times of administration.
    Amphetamine; Dextroamphetamine: (Moderate) Calcium carbonate is a gastrointestinal alkalinizing agent that may iincrease the oral absorption of amphetamines and increase amphetamine concentrations. To help limit an interaction, do not take caclium carbonate at the same time as the amphetamine product. It is recommended to separate times of administration.
    Amphetamines: (Moderate) Calcium carbonate is a gastrointestinal alkalinizing agent that may iincrease the oral absorption of amphetamines and increase amphetamine concentrations. To help limit an interaction, do not take caclium carbonate at the same time as the amphetamine product. It is recommended to separate times of administration.
    Anticholinergics: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Atazanavir: (Major) Atazanavir solubility decreases as gastric pH increases. Although drug interactions between atazanavir and antacids have not been specifically studied, based on data with other protease inhibitors, it is recommended that antacids not be given at the same time as atazanavir because of potential interference with absorption of atazanavir. Separate the administration of atazanavir and antacids to avoid the potential for interaction; give atazanavir 2 hours before or 1 hour after the antacid.
    Atazanavir; Cobicistat: (Major) Atazanavir solubility decreases as gastric pH increases. Although drug interactions between atazanavir and antacids have not been specifically studied, based on data with other protease inhibitors, it is recommended that antacids not be given at the same time as atazanavir because of potential interference with absorption of atazanavir. Separate the administration of atazanavir and antacids to avoid the potential for interaction; give atazanavir 2 hours before or 1 hour after the antacid.
    Atenolol: (Minor) Calcium antacids (e.g., calcium carbonate) and supplements (e.g., other oral calcium salts) have been reported to reduce the mean peak concentrations by 51% and the AUC of atenolol by 32%. In another study, antacids reduced the AUC of atenolol by 33%. Separate doses of atenolol and calcium-containing antacids or supplements by at least 2 hours to minimize this potential interaction,. However, most clinicians consider the interaction of atenolol with antacids to be of minor clinical significance, since clinical efficacy (heart rate and blood pressure parameters) appear to be unchanged under usual intermittent clinical use.
    Atenolol; Chlorthalidone: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended. (Minor) Calcium antacids (e.g., calcium carbonate) and supplements (e.g., other oral calcium salts) have been reported to reduce the mean peak concentrations by 51% and the AUC of atenolol by 32%. In another study, antacids reduced the AUC of atenolol by 33%. Separate doses of atenolol and calcium-containing antacids or supplements by at least 2 hours to minimize this potential interaction,. However, most clinicians consider the interaction of atenolol with antacids to be of minor clinical significance, since clinical efficacy (heart rate and blood pressure parameters) appear to be unchanged under usual intermittent clinical use.
    Atorvastatin; Ezetimibe: (Minor) Antacids (e.g., 20 ml aluminum hydroxide; magnesium hydroxide) have no significant effect on the oral bioavailability of total ezetimibe (ezetimibe plus ezetimibe-glucuronide), ezetimibe-glucuronide, or ezetimibe based on AUC values. However, the peak plasma concentration (Cmax) of total ezetimibe is decreased by 30%. The effect of the antacids in this regard is not expected to have a significant effect on the ability of ezetimibe to lower cholesterol. However, to limit any potential interaction, it would be prudent to administer ezetimibe at least 1 hour before or 2 hours after administering antacids.
    Atropine: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Atropine; Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Major) Avoid the concomitant use of calcium carbonate and methenamine. Calcium carbonate may cause the urine to become alkaline. This may reduce the effectiveness of methenamine by inhibiting its conversion to formaldehyde. (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Atropine; Difenoxin: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Atropine; Edrophonium: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Azilsartan; Chlorthalidone: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Baloxavir Marboxil: (Major) Do not administer baloxavir with products that contain calcium. Polyvalent cations, such as calcium, can chelate with baloxavir, reducing its absorption.
    Beclomethasone: (Moderate) Calcium absorption is reduced when calcium carbonate is taken concomitantly with systemic corticosteroids.
    Belladonna Alkaloids; Ergotamine; Phenobarbital: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Belladonna; Opium: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Bempedoic Acid; Ezetimibe: (Minor) Antacids (e.g., 20 ml aluminum hydroxide; magnesium hydroxide) have no significant effect on the oral bioavailability of total ezetimibe (ezetimibe plus ezetimibe-glucuronide), ezetimibe-glucuronide, or ezetimibe based on AUC values. However, the peak plasma concentration (Cmax) of total ezetimibe is decreased by 30%. The effect of the antacids in this regard is not expected to have a significant effect on the ability of ezetimibe to lower cholesterol. However, to limit any potential interaction, it would be prudent to administer ezetimibe at least 1 hour before or 2 hours after administering antacids.
    Benazepril; Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Bendroflumethiazide; Nadolol: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Major) Avoid the concomitant use of calcium carbonate and methenamine. Calcium carbonate may cause the urine to become alkaline. This may reduce the effectiveness of methenamine by inhibiting its conversion to formaldehyde. (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Benzphetamine: (Moderate) Calcium carbonate is a gastrointestinal alkalinizing agent that may iincrease the oral absorption of amphetamines and increase amphetamine concentrations. To help limit an interaction, do not take caclium carbonate at the same time as the amphetamine product. It is recommended to separate times of administration.
    Benztropine: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Betamethasone: (Moderate) Calcium absorption is reduced when calcium carbonate is taken concomitantly with systemic corticosteroids. Systemic corticosteroids induce a negative calcium balance by inhibiting intestinal calcium absorption as well as by increasing renal calcium losses. The mechanism by which these drugs inhibit calcium absorption in the intestine is likely to involve a direct inhibition of absorptive cell function.
    Bictegravir; Emtricitabine; Tenofovir Alafenamide: (Moderate) Administer bictegravir with food at the same time as oral calcium supplements. Routine administration of bictegravir under fasting conditions simultaneously with, or 2 hours after, calcium supplements is not recommended. Calcium is a polyvalent cation that can bind bictegravir in the GI tract. Taking these drugs simultaneously without food results in reduced bioavailability of bictegravir. In drug interaction studies, simultaneous administration of bictegravir with another calcium supplement under fasted conditions decreased the mean AUC of bictegravir by approximately 33%.
    Bisacodyl: (Moderate) By increasing intragastric pH, calcium carbonate can affect the dissolution of oral bisacodyl tablets; administration should be separated by 1 hour.
    Bisoprolol; Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Bosutinib: (Major) Bosutinib displays pH-dependent aqueous solubility; therefore, concomitant use of bosutinib and antacids may result in decreased plasma exposure of bosutinib. Separate the administration of bosutinib and antacids by more than 2 hours.
    Brompheniramine; Hydrocodone; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Brompheniramine; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Brompheniramine; Pseudoephedrine; Dextromethorphan: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Budesonide: (Moderate) Enteric-coated budesonide granules dissolve at a pH > 5.5. Likewise, the dissolution of the coating of extended-release budesonide tablets (Uceris) is pH dependent. Concomitant use of oral budesonide and antacids, milk, or other drugs that increase gastric pH levels can cause the coating of the granules to dissolve prematurely, possibly affecting release properties and absorption of the drug in the duodenum. In general, it may be prudent to avoid drugs such as antacids in combination with enteric-coated budesonide. In addition, calcium absorption is reduced when calcium carbonate is taken concomitantly with systemic corticosteroids. Systemic corticosteroids induce a negative calcium balance by inhibiting intestinal calcium absorption as well as by increasing renal calcium losses. The mechanism by which these drugs inhibit calcium absorption in the intestine is likely to involve a direct inhibition of absorptive cell function.
    Budesonide; Formoterol: (Moderate) Enteric-coated budesonide granules dissolve at a pH > 5.5. Likewise, the dissolution of the coating of extended-release budesonide tablets (Uceris) is pH dependent. Concomitant use of oral budesonide and antacids, milk, or other drugs that increase gastric pH levels can cause the coating of the granules to dissolve prematurely, possibly affecting release properties and absorption of the drug in the duodenum. In general, it may be prudent to avoid drugs such as antacids in combination with enteric-coated budesonide. In addition, calcium absorption is reduced when calcium carbonate is taken concomitantly with systemic corticosteroids. Systemic corticosteroids induce a negative calcium balance by inhibiting intestinal calcium absorption as well as by increasing renal calcium losses. The mechanism by which these drugs inhibit calcium absorption in the intestine is likely to involve a direct inhibition of absorptive cell function.
    Budesonide; Glycopyrrolate; Formoterol: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction. (Moderate) Enteric-coated budesonide granules dissolve at a pH > 5.5. Likewise, the dissolution of the coating of extended-release budesonide tablets (Uceris) is pH dependent. Concomitant use of oral budesonide and antacids, milk, or other drugs that increase gastric pH levels can cause the coating of the granules to dissolve prematurely, possibly affecting release properties and absorption of the drug in the duodenum. In general, it may be prudent to avoid drugs such as antacids in combination with enteric-coated budesonide. In addition, calcium absorption is reduced when calcium carbonate is taken concomitantly with systemic corticosteroids. Systemic corticosteroids induce a negative calcium balance by inhibiting intestinal calcium absorption as well as by increasing renal calcium losses. The mechanism by which these drugs inhibit calcium absorption in the intestine is likely to involve a direct inhibition of absorptive cell function.
    Cabotegravir: (Moderate) Administer oral calcium at least two hours before or four hours after taking oral cabotegravir. Calcium is a polyvalent cation that can bind cabotegravir in the GI tract. Taking these drugs simultaneously may result in reduced oral bioavailability of cabotegravir.
    Cabotegravir; Rilpivirine: (Moderate) Administer oral calcium at least two hours before or four hours after taking oral cabotegravir. Calcium is a polyvalent cation that can bind cabotegravir in the GI tract. Taking these drugs simultaneously may result in reduced oral bioavailability of cabotegravir. (Moderate) Concurrent administration of rilpivirine and antacids may significantly decrease rilpivirine plasma concentrations, potentially resulting in treatment failure. To decrease the risk of virologic failure, avoid use of antacids for at least 2 hours before and at least 4 hours after administering rilpivirine.
    Calcipotriene: (Minor) There is evidence that calcipotriene can be absorbed in amounts that are sufficient to produce systemic effects, including elevated serum calcium; hypercalcemia has been observed in normal prescription use. Use calcipotriene cautiously with other agents that can produce hypercalcemia (e.g., calcium salts or supplements including calcium carbonate).
    Calcipotriene; Betamethasone: (Minor) There is evidence that calcipotriene can be absorbed in amounts that are sufficient to produce systemic effects, including elevated serum calcium; hypercalcemia has been observed in normal prescription use. Use calcipotriene cautiously with other agents that can produce hypercalcemia (e.g., calcium salts or supplements including calcium carbonate).
    Calcitonin: (Moderate) Calcitonin is given to hypercalcemic patients to reduce serum calcium concentrations. For the treatment of hypercalcemia, calcium supplements should be avoided. Calcium salts, including calcium carbonate, can elevate serum calcium concentrations and antagonize the effects of the calcitonin for this condition. For the treatment of osteoporosis adequate intake of calcium salts are 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.
    Calcium Carbonate; Risedronate: (Moderate) Separate administration of oral risedronate and calcium-containing supplements by at least 2 hours. Calcium will interfere with the absorption of oral risedronate.
    Calcium Phosphate, Supersaturated: (Moderate) The concomitant use of oral sodium phosphate monobasic monohydrate; sodium phosphate dibasic anhydrous preparations in conjunction with antacids containing calcium (e.g., calcium carbonate, calcium salts) may bind the phosphate in the stomach and reduce its absorption. If the patient requires multiple mineral supplements or concurrent use of antacids, it is prudent to separate the administration of sodium phosphate salts from calcium containing products by at least one hour.
    Candesartan; Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Captopril: (Major) Antacids can decrease the GI absorption of captopril if administered simultaneously.
    Captopril; Hydrochlorothiazide, HCTZ: (Major) Antacids can decrease the GI absorption of captopril if administered simultaneously. (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Carbetapentane; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Carbinoxamine; Dextromethorphan; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Carbinoxamine; Hydrocodone; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Carbinoxamine; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Cardiac glycosides: (Moderate) Monitor serum calcium regularly in patients receiving digoxin. Calcium salts augment the actions of digoxin. In addition, when calcium is administered via rapid intravenous injection, the risk of serious arrhythmias in digitalized patients is increased.
    Castor Oil: (Moderate) Absorption of fat-soluble vitamins may be decreased with coadministration of castor oil.
    Cefpodoxime: (Moderate) Because cefpodoxime proxetil requires a low gastric pH for dissolution, drugs which increase gastric pH, such as antacids, can decrease the bioavailability of cefpodoxime.
    Cefuroxime: (Moderate) Antacids can interfere with the oral absorption of cefuroxime axetil and may result in reduced antibiotic efficacy. If an antacid must be used while a patient is taking cefuroxime, administer the oral dosage of cefuroxime at least 1 hour before or 2 hours after the antacid.
    Cetirizine; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Chlophedianol; Dexchlorpheniramine; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Chlordiazepoxide; Clidinium: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Chloroquine: (Major) Chloroquine absorption may be reduced by antacids. Administer chloroquine and antacids at least 4 hours apart.
    Chlorothiazide: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Chlorpheniramine; Dihydrocodeine; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Chlorpheniramine; Guaifenesin; Hydrocodone; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Chlorpheniramine; Hydrocodone; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Chlorpheniramine; Ibuprofen; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Chlorpheniramine; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Chlorthalidone: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Chlorthalidone; Clonidine: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Cholestyramine: (Moderate) Cholestyramine can decrease the intestinal absorption of fat and fat-soluble vitamins. If used concurrently, administration of the two agents should be staggered for the longest time interval possible.
    Ciprofloxacin: (Moderate) Administer oral ciprofloxacin at least 2 hours before or 6 hours after oral products that contain calcium. Ciprofloxacin absorption may be reduced as quinolone antibiotics can chelate with divalent or trivalent cations. Examples of compounds that may interfere with quinolone bioavailability include antacids and multivitamins that contain calcium.
    Codeine; Guaifenesin; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Colesevelam: (Moderate) It is not known if colesevelam can reduce the absorption of oral vitamin supplements including fat soluble vitamins A, D, E, and K. To minimize potential interactions, administer vitamins at least 4 hours before colesevelam.
    Colestipol: (Moderate) Separate administration of fat-soluble vitamins 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.
    Conjugated Estrogens: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Conjugated Estrogens; Bazedoxifene: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Conjugated Estrogens; Medroxyprogesterone: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Corticotropin, ACTH: (Moderate) Calcium absorption is reduced when calcium carbonate is taken concomitantly with systemic corticosteroids. Systemic corticosteroids induce a negative calcium balance by inhibiting intestinal calcium absorption as well as by increasing renal calcium losses. The mechanism by which these drugs inhibit calcium absorption in the intestine is likely to involve a direct inhibition of absorptive cell function. Patients taking systemic corticosteroids should ensure proper intake of calcium as directed by their health care provider.
    Cortisone: (Moderate) Calcium absorption is reduced when calcium carbonate is taken concomitantly with systemic corticosteroids. Systemic corticosteroids induce a negative calcium balance by inhibiting intestinal calcium absorption as well as by increasing renal calcium losses. The mechanism by which these drugs inhibit calcium absorption in the intestine is likely to involve a direct inhibition of absorptive cell function.
    Cysteamine: (Major) In general, cysteamine may be administered with electrolyte and mineral replacements necessary for managing Fanconi syndrome, as well as with vitamin D and thyroid hormone. However, delayed-release cysteamine (Procysbi) should be administered at least 1 hour before or 1 after medications that increase gastric pH, including those containing bicarbonate or carbonate (i.e.calcium carbonate). Drugs that increase the gastric pH, such as bicarbonate and carbonate, may cause the premature release of cysteamine from delayed-release capsules, leading to an increase in WBC cystine concentration.
    Dabrafenib: (Moderate) Space the administration of antacids from dabrafenib by at least 2 hours. Antacids elevate the gastric pH and may alter the solubility of dabrafenib. Therefore, the concomitant use of dabrafenib and antacids may reduce the systemic exposure and bioavailability of dabrafenib. No formal trials have been performed to evaluate this interaction and it is not known how this interaction affects the efficacy of dabrafenib.
    Dasatinib: (Moderate) Separate the administration of dasatinib and calcium carbonate by at least 2 hours if these agents are used together. The simultaneous administration of an antacid with dasatinib decreased the Cmax and AUC of dasatinib by 58% and 55%, respectively.
    Delafloxacin: (Major) Administer oral delafloxacin at least 2 hours before or 6 hours after oral products that contain calcium. Delafloxacin absorption may be reduced as quinolone antibiotics can chelate with divalent or trivalent cations. Examples of compounds that may interfere with fluoroquinolone bioavailability include antacids and multivitamins that contain calcium.
    Delavirdine: (Major) Coadministration of delavirdine with antacids results in decreased absorption of delavirdine. Administration of delavirdine and antacids should be separated by at least 1 hour.
    Desloratadine; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Desogestrel; Ethinyl Estradiol: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Dexamethasone: (Moderate) Calcium absorption is reduced when calcium carbonate is taken concomitantly with systemic corticosteroids. Systemic corticosteroids induce a negative calcium balance by inhibiting intestinal calcium absorption as well as by increasing renal calcium losses. The mechanism by which these drugs inhibit calcium absorption in the intestine is likely to involve a direct inhibition of absorptive cell function.
    Dexbrompheniramine; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Dexchlorpheniramine; Dextromethorphan; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Dextroamphetamine: (Moderate) Calcium carbonate is a gastrointestinal alkalinizing agent that may iincrease the oral absorption of amphetamines and increase amphetamine concentrations. To help limit an interaction, do not take caclium carbonate at the same time as the amphetamine product. It is recommended to separate times of administration.
    Dextromethorphan; Guaifenesin; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Dextromethorphan; Quinidine: (Major) By increasing urinary pH, calcium carbonate can decrease the urinary excretion of quinidine.
    Diazepam: (Moderate) The coadministration of diazepam with antacids results in delayed diazepam absorption due to the fact that antacids delay gastric emptying. It may be prudent to separate dosing by 2 hours to limit any potential interaction.
    Dicyclomine: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Dienogest; Estradiol valerate: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Diethylstilbestrol, DES: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Diflunisal: (Moderate) Concurrent use of diflunisal with antacids, such as calcium carbonate, may reduce plasma diflunisal concentrations. The effect may be clinically significant if antacids are used on a continuous schedule.
    Dihydrocodeine; Guaifenesin; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Diphenoxylate; Atropine: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Dolutegravir: (Moderate) Administer dolutegravir 2 hours before or 6 hours after taking supplements containing calcium if given under fasting conditions. When taken with food, dolutegravir and supplements containing calcium can be taken at the same time. Simultaneous administration under fasted conditions may result in reduced bioavailability of dolutegravir.
    Dolutegravir; Lamivudine: (Moderate) Administer dolutegravir 2 hours before or 6 hours after taking supplements containing calcium if given under fasting conditions. When taken with food, dolutegravir and supplements containing calcium can be taken at the same time. Simultaneous administration under fasted conditions may result in reduced bioavailability of dolutegravir.
    Dolutegravir; Rilpivirine: (Moderate) Administer dolutegravir 2 hours before or 6 hours after taking supplements containing calcium if given under fasting conditions. When taken with food, dolutegravir and supplements containing calcium can be taken at the same time. Simultaneous administration under fasted conditions may result in reduced bioavailability of dolutegravir. (Moderate) Concurrent administration of rilpivirine and antacids may significantly decrease rilpivirine plasma concentrations, potentially resulting in treatment failure. To decrease the risk of virologic failure, avoid use of antacids for at least 2 hours before and at least 4 hours after administering rilpivirine.
    Drospirenone; Estetrol: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Drospirenone; Estradiol: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Drospirenone; Ethinyl Estradiol: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Drospirenone; Ethinyl Estradiol; Levomefolate: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Edetate Calcium Disodium, Calcium EDTA: (Major) Because edetate disodium chelates and lowers serum calcium, oral or parenteral calcium salts should not be administered concomitantly.
    Edetate Disodium, Disodium EDTA: (Major) Because edetate disodium chelates and lowers serum calcium, oral or parenteral calcium salts should not be administered concomitantly.
    Elagolix; Estradiol; Norethindrone acetate: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Eltrombopag: (Major) Eltrombopag chelates polyvalent cations (e.g., calcium, aluminum, and magnesium) in food, mineral supplements, and antacids. In a clinical study, systemic exposure to eltrombopag was decreased by 70% when it was administered with a polyvalent cation-containing antacid. Administer eltrombopag at least 2 hours before or 4 hours after any oral products containing polyvalent cations, such as aluminum salts, (like aluminum hydroxide), calcium salts, (including calcium carbonate), and magnesium salts.
    Elvitegravir: (Moderate) Separate administration of elvitegravir and calcium by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
    Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Alafenamide: (Moderate) Separate administration of elvitegravir and calcium by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
    Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Disoproxil Fumarate: (Moderate) Separate administration of elvitegravir and calcium by at least 2 hours. Due to the formation of ionic complexes in the gastrointestinal tract, simultaneous administration results in lower elvitegravir plasma concentrations.
    Emtricitabine; Rilpivirine; Tenofovir alafenamide: (Moderate) Concurrent administration of rilpivirine and antacids may significantly decrease rilpivirine plasma concentrations, potentially resulting in treatment failure. To decrease the risk of virologic failure, avoid use of antacids for at least 2 hours before and at least 4 hours after administering rilpivirine.
    Emtricitabine; Rilpivirine; Tenofovir disoproxil fumarate: (Moderate) Concurrent administration of rilpivirine and antacids may significantly decrease rilpivirine plasma concentrations, potentially resulting in treatment failure. To decrease the risk of virologic failure, avoid use of antacids for at least 2 hours before and at least 4 hours after administering rilpivirine.
    Enalapril; Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Eprosartan; Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Erdafitinib: (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.
    Erlotinib: (Major) Separate administration by several hours if concomitant use of erlotinib with calcium carbonate is necessary. Erlotinib displays pH-dependent solubility with decreased solubility at a higher pH; the increased gastric pH resulting from calcium carbonate therapy may reduce the bioavailability of erlotinib. Increasing the dose of erlotinib without modifying the administration schedule is unlikely to compensate for loss of exposure. The effects of antacids on erlotinib pharmacokinetics has not been evaluated.
    Esterified Estrogens: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Esterified Estrogens; Methyltestosterone: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Estradiol Cypionate; Medroxyprogesterone: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Estradiol: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Estradiol; Levonorgestrel: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Estradiol; Norethindrone: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Estradiol; Norgestimate: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Estradiol; Progesterone: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Estramustine: (Major) Administration of estramustine with calcium impairs the oral absorption of estramustine significantly, due to formation of a calcium-phosphate complex. Calcium-containing drugs must not be taken simultaneously with estramustine. Patients should be instructed to take estramustine with water at least 1 hour before or 2 hours after calcium supplements.
    Estrogens: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Estropipate: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Ethinyl Estradiol: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Ethinyl Estradiol; Levonorgestrel; Folic Acid; Levomefolate: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Ethinyl Estradiol; Norelgestromin: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Ethinyl Estradiol; Norethindrone Acetate: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Ethinyl Estradiol; Norgestrel: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Ethotoin: (Major) Oral absorption of phenytoin can be reduced by calcium salts. Calcium salts can form complexes that are nonabsorbable. Separating the administration of phenytoin and calcium salts by at least 2 hours to help avoid this interaction. A similar interaction may occur with ethotoin.
    Ethynodiol Diacetate; Ethinyl Estradiol: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Etidronate: (Moderate) Separate administration of oral etidronate and calcium-containing supplements by at least 2 hours. Calcium will interfere with the absorption of oral etidronate.
    Etonogestrel; Ethinyl Estradiol: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Ezetimibe: (Minor) Antacids (e.g., 20 ml aluminum hydroxide; magnesium hydroxide) have no significant effect on the oral bioavailability of total ezetimibe (ezetimibe plus ezetimibe-glucuronide), ezetimibe-glucuronide, or ezetimibe based on AUC values. However, the peak plasma concentration (Cmax) of total ezetimibe is decreased by 30%. The effect of the antacids in this regard is not expected to have a significant effect on the ability of ezetimibe to lower cholesterol. However, to limit any potential interaction, it would be prudent to administer ezetimibe at least 1 hour before or 2 hours after administering antacids.
    Ezetimibe; Simvastatin: (Minor) Antacids (e.g., 20 ml aluminum hydroxide; magnesium hydroxide) have no significant effect on the oral bioavailability of total ezetimibe (ezetimibe plus ezetimibe-glucuronide), ezetimibe-glucuronide, or ezetimibe based on AUC values. However, the peak plasma concentration (Cmax) of total ezetimibe is decreased by 30%. The effect of the antacids in this regard is not expected to have a significant effect on the ability of ezetimibe to lower cholesterol. However, to limit any potential interaction, it would be prudent to administer ezetimibe at least 1 hour before or 2 hours after administering antacids.
    Ferric Maltol: (Moderate) Antacids (e.g., calcium carbonate, aluminum hydroxide, or magnesium hydroxide) may decrease the absorption of oral iron preparations (e.g., iron salts or polysaccharide-iron complex). At higher pH values, iron is more readily ionized to its ferric state and is more poorly absorbed. Doses of antacids and iron should be taken as far apart as possible to minimize the potential for interaction.
    Fexofenadine: (Moderate) Co-administration with antacids within 15 minutes decreases the AUC and Cmax of fexofenadine. Separate administration is recommended.
    Fexofenadine; Pseudoephedrine: (Moderate) Co-administration with antacids within 15 minutes decreases the AUC and Cmax of fexofenadine. Separate administration is recommended. (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Flavoxate: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Fludrocortisone: (Moderate) Calcium absorption is reduced when calcium carbonate is taken concomitantly with systemic corticosteroids.
    Flunisolide: (Moderate) Calcium absorption is reduced when calcium carbonate is taken concomitantly with systemic corticosteroids.
    Fosamprenavir: (Moderate) The administration of an aluminum hydroxide and magnesium hydroxide containing antacid with fosamprenavir decreased fosamprenavir Cmax and AUC. It is recommended that the administration of fosamprenavir and antacids be separated by at least 1 hour.
    Fosinopril: (Moderate) Coadministration of antacids with fosinopril may impair absorption of fosinopril. Therefore, if concomitant administration of these agents is indicated, dosing should be separated by 2 hours.
    Fosinopril; Hydrochlorothiazide, HCTZ: (Moderate) Coadministration of antacids with fosinopril may impair absorption of fosinopril. Therefore, if concomitant administration of these agents is indicated, dosing should be separated by 2 hours. (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Gabapentin: (Moderate) Antacids (e.g., aluminum hydroxide; magnesium hydroxide) have been shown to reduce the oral bioavailability of gabapentin by roughly 20%. This decrease in bioavailability was about 5% when gabapentin was administered 2 hours after the antacid. It is recommended that gabapentin be taken at least 2 hours following the administration of antacids in order to avoid a significant interaction.
    Gallium: (Moderate) Concurrent administration products containing calcium salts may antagonize the effects of gallium nitrate.
    Gastrointestinal Enzymes: (Major) The effectiveness of gastrointestinal enzymes can be diminished with concurrent administration of antacids. In-vitro studies suggest that calcium and magnesum cations exert their deleterious effect on replacement enzyme therapy by formation of poorly soluble calcium or magnesium soaps and precipitation of glycine conjugated bile salts.
    Gefitinib: (Major) Avoid coadministration of calcium carbonate with gefitinib if possible due to decreased exposure to gefitinib, which may lead to reduced efficacy. If concomitant use is unavoidable, take gefitinib 6 hours after the last dose or 6 hours before the next dose of calcium carbonate. Gefitinib exposure is affected by gastric pH. Coadministration with another drug to maintain gastric pH above 5 decreased gefitinib exposure by 47%.
    Glipizide: (Moderate) Antacids have been reported to increase the absorption of glipizide, enhancing their hypoglycemic effects. Although the exact mechanism is not known, theoretically it may be due to alterations in gastric pH. Consider closely monitoring blood glucose concentrations.
    Glipizide; Metformin: (Moderate) Antacids have been reported to increase the absorption of glipizide, enhancing their hypoglycemic effects. Although the exact mechanism is not known, theoretically it may be due to alterations in gastric pH. Consider closely monitoring blood glucose concentrations.
    Glyburide: (Moderate) Antacids have been reported to increase the absorption of non-micronized glyburide, enhancing their hypoglycemic effects. Although the exact mechanism is not known, theoretically it may be due to alterations in gastric pH. Consider closely monitoring blood glucose concentrations.
    Glyburide; Metformin: (Moderate) Antacids have been reported to increase the absorption of non-micronized glyburide, enhancing their hypoglycemic effects. Although the exact mechanism is not known, theoretically it may be due to alterations in gastric pH. Consider closely monitoring blood glucose concentrations.
    Glycopyrrolate: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Glycopyrrolate; Formoterol: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Guaifenesin; Hydrocodone; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Guaifenesin; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Homatropine; Hydrocodone: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Hydantoins: (Moderate) Phenytoin and fosphenytoin can decrease the activity of vitamin D (e.g., cholecalciferol) 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. (Moderate) Phenytoin and fosphenytoin can decrease the activity of vitamin D (e.g., cholecalciferol, ergocalciferol) 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) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Hydrochlorothiazide, HCTZ; Methyldopa: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Hydrochlorothiazide, HCTZ; Moexipril: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Hydrocodone; Potassium Guaiacolsulfonate; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Hydrocodone; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Hydroxychloroquine: (Moderate) Hydroxychloroquine absorption may be reduced by antacids as has been observed with the structurally similar chloroquine. Administer hydroxychloroquine and antacids at least 4 hours apart. Of note, a study demonstrated no significant difference in hydroxychloroquine serum concentration in patients taking concomitant antacids (n = 14) compared to those not taking antacids (n = 495).
    Hyoscyamine: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate; Sodium Biphosphate: (Major) Avoid the concomitant use of calcium carbonate and methenamine. Calcium carbonate may cause the urine to become alkaline. This may reduce the effectiveness of methenamine by inhibiting its conversion to formaldehyde. (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Ibandronate: (Moderate) Separate administration of oral ibandronate and calcium-containing supplements by at least 1 hour. Calcium will interfere with the absorption of oral ibandronate.
    Ibritumomab Tiuxetan: (Moderate) The oral absorption of phosphorus is reduced by ingestion of pharmacologic doses of calcium carbonate or other phosphate-lowering calcium salts (e.g., calcium acetate). There is, however, no significant interference with phosphorus absorption by oral dietary calcium at intakes within the typical adult range. If the patient requires multiple calcium supplements or a calcium-containing antacid, it may be wise to separate the administration of phosphorus salts from calcium-containing products. In some instances the administration of calcium salts or calcium carbonate is used therapeutically (e.g., uremia) to decrease serum phosphorus levels, so the administration of phosphorus supplements would dynamically counteract the intended use of calcium in these settings, assuming hypophosphatemia is not present. Appropriate calcium-phosphorus ratios in vivo are important for proper calcium homeostasis in tissues and bone; if the serum ionized calcium concentration is elevated, the concomitant use of calcium salts and phosphorus salts may increase the risk of calcium deposition in soft tissue.
    Ibuprofen; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Indacaterol; Glycopyrrolate: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Indomethacin: (Moderate) Antacids may inhibit the oral absorption of indomethacin. Simultaneous administration should be avoided; separate dosing by at least 2 hours to limit an interaction.
    Infigratinib: (Moderate) Separate the administration of infigratinib and locally acting antacids such as calcium carbonate if concomitant use is necessary. Coadministration may decrease infigratinib exposure resulting in decreased efficacy. Administer infigratinib two hours before or after calcium carbonate.
    Irbesartan; Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Iron Salts: (Moderate) Antacids (e.g., calcium carbonate, aluminum hydroxide, or magnesium hydroxide) may decrease the absorption of oral iron preparations (e.g., iron salts or polysaccharide-iron complex). At higher pH values, iron is more readily ionized to its ferric state and is more poorly absorbed. Doses of antacids and iron should be taken as far apart as possible to minimize the potential for interaction.
    Iron: (Moderate) Antacids (e.g., calcium carbonate, aluminum hydroxide, or magnesium hydroxide) may decrease the absorption of oral iron preparations (e.g., iron salts or polysaccharide-iron complex). At higher pH values, iron is more readily ionized to its ferric state and is more poorly absorbed. Doses of antacids and iron should be taken as far apart as possible to minimize the potential for interaction.
    Isoniazid, INH; Pyrazinamide, PZA; Rifampin: (Moderate) Concomitant use of calcium carbonate and rifampin may decrease the absorption of rifampin. Daily doses of rifampin should be given at least 1 hour before the ingestion of calcium carbonate. (Moderate) Rifampin is a potent inducer of the cytochrome P450 hepatic enzyme system and can decrease the plasma concentrations and possibly the efficacy of cholecalciferol, Vitamin D3. In some cases, reduced concentrations of circulating vitamin D and 1,25-dihydoxy vitamin D have been accompanied by decreased serum calcium and phosphate, and elevated parathyroid hormone. Dosage adjustments of cholecalciferol, Vitamin D3 may be required. (Moderate) Rifampin is a potent inducer of the cytochrome P450 hepatic enzyme system and can decrease the plasma concentrations and possibly the efficacy of ergocalciferol, Vitamin D2. In some cases, reduced concentrations of circulating vitamin D and 1,25-dihydoxy vitamin D have been accompanied by decreased serum calcium and phosphate, and elevated parathyroid hormone. Dosage adjustments of ergocalciferol, Vitamin D2 may be required.
    Isoniazid, INH; Rifampin: (Moderate) Concomitant use of calcium carbonate and rifampin may decrease the absorption of rifampin. Daily doses of rifampin should be given at least 1 hour before the ingestion of calcium carbonate. (Moderate) Rifampin is a potent inducer of the cytochrome P450 hepatic enzyme system and can decrease the plasma concentrations and possibly the efficacy of cholecalciferol, Vitamin D3. In some cases, reduced concentrations of circulating vitamin D and 1,25-dihydoxy vitamin D have been accompanied by decreased serum calcium and phosphate, and elevated parathyroid hormone. Dosage adjustments of cholecalciferol, Vitamin D3 may be required. (Moderate) Rifampin is a potent inducer of the cytochrome P450 hepatic enzyme system and can decrease the plasma concentrations and possibly the efficacy of ergocalciferol, Vitamin D2. In some cases, reduced concentrations of circulating vitamin D and 1,25-dihydoxy vitamin D have been accompanied by decreased serum calcium and phosphate, and elevated parathyroid hormone. Dosage adjustments of ergocalciferol, Vitamin D2 may be required.
    Itraconazole: (Moderate) When administering antacids with the 100 mg itraconazole capsule and 200 mg itraconazole tablet formulations, systemic exposure to itraconazole is decreased. Conversely, exposure to itraconazole is increased when antacids are administered with the 65 mg itraconazole capsule. Administer antacids at least 2 hours before or 2 hours after the 100 mg capsule or 200 mg tablet. Monitor for increased itraconazole-related adverse effects if antacids are administered with itraconazole 65 mg capsules.
    Ketoconazole: (Moderate) Administer calcium carbonate at least 1 hour before or 2 hours after taking ketoconazole. Antacids can impair the absorption of ketoconazole.
    Lactulose: (Minor) Oral, nonabsorbable antacids may interfere with the decrease in colon pH necessary for lactulose's action.
    Ledipasvir; Sofosbuvir: (Moderate) Separate administration of ledipasvir and antacids by at least 4 hours. Solubility of ledipasvir decreases as gastric pH increases; thus, simultaneous administration of these drugs may result in lower ledipasvir plasma concentrations.
    Levofloxacin: (Moderate) Administer oral products that contain calcium at least 2 hours before or 2 hours after orally administered levofloxacin. Levofloxacin absorption may be reduced as quinolone antibiotics can chelate with divalent or trivalent cations. Chelation of divalent cations with levofloxacin is less than with other quinolones. Examples of compounds that may interfere with quinolone bioavailability include antacids and multivitamins that contain calcium.
    Levoketoconazole: (Moderate) Administer calcium carbonate at least 1 hour before or 2 hours after taking ketoconazole. Antacids can impair the absorption of ketoconazole.
    Levonorgestrel; Ethinyl Estradiol: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Levonorgestrel; Ethinyl Estradiol; Ferrous Bisglycinate: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Lisdexamfetamine: (Moderate) Calcium carbonate is a gastrointestinal alkalinizing agent that may iincrease the oral absorption of amphetamines and increase amphetamine concentrations. To help limit an interaction, do not take caclium carbonate at the same time as the amphetamine product. It is recommended to separate times of administration.
    Lisinopril; Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Loratadine; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Losartan; Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Magnesium Citrate: (Moderate) Magnesium-containing drug products, such as magnesium citrate, should be used cautiously in patients receiving vitamin D. Because vitamin D can increase serum magnesium concentrations, the combined use of vitamin D 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 (cholecalciferol). Because vitamin D can increase serum magnesium concentrations, the combined use of vitamin D and magnesium-containing drug products should be avoided, if possible, in patients with chronic renal failure.
    Magnesium: (Moderate) Magnesium-containing drug products and magnesium salts should be used cautiously in patients receiving vitamin D. Because vitamin D can increase serum magnesium concentrations, the combined use of vitamin D and magnesium-containing drug products should be avoided, if possible, in patients with chronic renal failure.
    Mefenamic Acid: (Moderate) Ingestion of mefenamic acid with antacids is not recommended. Administration with an antacid containing 1.7 grams of magnesium hydroxide resulted in a 36 percent increase in the area under the time versus concentration curve of mefenamic acid.
    Mefloquine: (Moderate) Antacids, H2-blockers, and proton pump inhibitors (PPIs) may increase plasma concentrations of mefloquine. In a small study involving 6 healthy subjects and 6 peptic ulcer patients, cimetidine increased the Cmax and AUC of mefloquine. In the study, the pharmacokinetics of mefloquine were determined after receiving a single oral mefloquine 500 mg dose alone and after 3-days of cimetidine 400 mg PO bid. In both healthy subjects and peptic ulcer patients, mefloquine Cmax was increased 42.4% and 20.5%, respectively, and AUC was increased by 37.5% in both groups. Elimination half-life, total clearance, and volume of distribution were not significantly affected. An increase in adverse reactions was not noted. Patients on chronic mefloquine therapy might be at increased risk of adverse reactions, especially in patients with a neurological or psychiatric history.
    Mepenzolate: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Mesalamine, 5-ASA: (Moderate) Do not coadminister mesalamine extended-release capsules (Apriso) with antacids. Apriso is a pH-dependent, delayed-release capsule product with an enteric coating that dissolves at a pH of at least 6. Other mesalamine products do not have an interaction with antacids.
    Mestranol; Norethindrone: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Methamphetamine: (Moderate) Calcium carbonate is a gastrointestinal alkalinizing agent that may iincrease the oral absorption of amphetamines and increase amphetamine concentrations. To help limit an interaction, do not take caclium carbonate at the same time as the amphetamine product. It is recommended to separate times of administration.
    Methenamine: (Major) Avoid the concomitant use of calcium carbonate and methenamine. Calcium carbonate may cause the urine to become alkaline. This may reduce the effectiveness of methenamine by inhibiting its conversion to formaldehyde.
    Methenamine; Sodium Acid Phosphate: (Major) Avoid the concomitant use of calcium carbonate and methenamine. Calcium carbonate may cause the urine to become alkaline. This may reduce the effectiveness of methenamine by inhibiting its conversion to formaldehyde.
    Methenamine; Sodium Acid Phosphate; Methylene Blue; Hyoscyamine: (Major) Avoid the concomitant use of calcium carbonate and methenamine. Calcium carbonate may cause the urine to become alkaline. This may reduce the effectiveness of methenamine by inhibiting its conversion to formaldehyde. (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Methscopolamine: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Methyclothiazide: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Metolazone: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Metoprolol; Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Mineral Oil: (Moderate) Absorption of fat-soluble vitamins is reported to be decreased with prolonged oral administration of mineral oil. However, despite warnings in various texts, there is little direct evidence that the interaction is of practical/clinical importance with limited use as directed. It may be prudent for those taking dietary supplements of Vitamin A, D, E, or K to separate administration by 1 hour before or 4 hours after a mineral oil oral dosage to help limit absorption interactions. Theoretically, the effect on fat-soluble vitamin absorption may more likely occur with prolonged or chronic administration of mineral oil.
    Moxifloxacin: (Major) Administer oral moxifloxacin at least 4 hours before or 8 hours after oral products that contain calcium. Moxifloxacin absorption may be reduced as quinolone antibiotics can chelate with divalent or trivalent cations. Examples of compounds that may interfere with quinolone bioavailability include antacids and multivitamins that contain calcium.
    Mycophenolate: (Major) Coadministration of mycophenolate mofetil with antacids decreases the bioavailability of mycophenolate mofetil. Aluminum or magnesium hydroxide antacids decrease AUC of mycophenolic acid by about 17%. Avoid administration of mycophenolate mofetil with agents that may decrease its absorption.
    Naproxen; Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Neratinib: (Major) Administer neratinib at least 3 hours after administration of calcium carbonate if concomitant use is necessary due to decreased absorption and systemic exposure of neratinib; the solubility of neratinib decreases with increasing pH of the GI tract.
    Neuromuscular blockers: (Moderate) Concomitant use of neuromuscular blockers and calcium may result in resistance to neuromuscular blockade. Calcium antagonizes the potentiating effect of magnesium on neuromuscular blockade. Also, calcium triggers acetylcholine release, and therefore, may both reduce the sensitivity to neuromuscular blockers and decrease the duration of neuromuscular blockade.
    Nilotinib: (Moderate) If concomitant use of these agents is necessary, administer the antacid approximately 2 hours before or approximately 2 hours after the nilotinib dose. Nilotinib displays pH-dependent solubility with decreased solubility at a higher pH; therefore, concomitant use of nilotinib and antacids may result in decreased bioavailability of nilotinib. In a study in healthy subjects, there was no significant change in nilotinib pharmacokinetics when an antacid (aluminum hydroxide/magnesium hydroxide/simethicone) was administered approximately 2 hours before or approximately 2 hours after a single 400-mg nilotinib dose.
    Nitrofurantoin: (Moderate) Separate administration of antacids and nitrofurantoin by at least 1 hour. Antacids can delay both the rate and the extent of GI absorption of nitrofurantoin. This interaction may be due to surface absorption of the antibacterial onto the antacid.
    Norethindrone Acetate; Ethinyl Estradiol; Ferrous fumarate: (Moderate) Antacids (e.g., calcium carbonate, aluminum hydroxide, or magnesium hydroxide) may decrease the absorption of oral iron preparations (e.g., iron salts or polysaccharide-iron complex). At higher pH values, iron is more readily ionized to its ferric state and is more poorly absorbed. Doses of antacids and iron should be taken as far apart as possible to minimize the potential for interaction. (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Norethindrone; Ethinyl Estradiol: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Norethindrone; Ethinyl Estradiol; Ferrous fumarate: (Moderate) Antacids (e.g., calcium carbonate, aluminum hydroxide, or magnesium hydroxide) may decrease the absorption of oral iron preparations (e.g., iron salts or polysaccharide-iron complex). At higher pH values, iron is more readily ionized to its ferric state and is more poorly absorbed. Doses of antacids and iron should be taken as far apart as possible to minimize the potential for interaction. (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Norfloxacin: (Major) Administer oral products that contain calcium at least 2 hours before or 2 hours after norfloxacin. Norfloxacin absorption may be reduced as quinolone antibiotics can chelate with divalent or trivalent cations. Examples of compounds that may interfere with quinolone bioavailability include antacids and multivitamins that contain calcium.
    Norgestimate; Ethinyl Estradiol: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Octreotide: (Moderate) Coadministration of oral octreotide with antacids may require increased doses of octreotide. Coadministration of oral octreotide with drugs that alter the pH of the upper GI tract, including antacids, may alter the absorption of octreotide and lead to a reduction in bioavailability.
    Ofloxacin: (Moderate) Administer oral products that contain calcium at least 2 hours before or 2 hours after ofloxacin. Ofloxacin absorption may be reduced as quinolone antibiotics can chelate with divalent or trivalent cations. Examples of compounds that may interfere with quinolone bioavailability include antacids and multivitamins that contain calcium.
    Olmesartan; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Olmesartan; Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Orlistat: (Moderate) Orlistat reduced the absorption of fat-soluble vitamins during clinical trials. The bioavailability of orally administered vitamin D may also be decreased. In patients receiving orally-administered vitamin D with orlistat, close monitoring is recommended. In addition, the manufacturer recommends that fat-soluble vitamins be administered at least 2 hours before or after the administration of orlistat to limit effects on oral absorption.
    Oxybutynin: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Pancrelipase: (Major) The effectiveness of gastrointestinal enzymes can be diminished with concurrent administration of antacids. In-vitro studies suggest that calcium and magnesum cations exert their deleterious effect on replacement enzyme therapy by formation of poorly soluble calcium or magnesium soaps and precipitation of glycine conjugated bile salts.
    Pazopanib: (Moderate) Separate administration of pazopanib and antacids by several hours if coadministration is necessary in order to avoid a reduction in pazopanib exposure, which may decrease efficacy.
    Penicillamine: (Moderate) Because penicillamine chelates heavy metals, it is possible that antacids could reduce penicillamine bioavailability, which can decrease the therapeutic effects of penicillamine. Simultaneous administration should be avoided; separate dosing by at least 2 hours to limit an interaction.
    Phenobarbital; Hyoscyamine; Atropine; Scopolamine: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Phenytoin: (Moderate) Calcium carbonate can significantly decrease the oral bioavailability of phenytoin. Calcium carbonate should not affect the pharmacokinetics of parenteral phenytoin. Separating the administration of phenytoin and calcium carbonate by at least 2 hours will help minimize the possibility of an interaction.
    Phosphorated Carbohydrate Solution: (Moderate) The oral absorption of phosphorus is reduced by ingestion of pharmacologic doses of calcium carbonate or other phosphate-lowering calcium salts (e.g., calcium acetate). There is, however, no significant interference with phosphorus absorption by oral dietary calcium at intakes within the typical adult range. If the patient requires multiple calcium supplements or a calcium-containing antacid, it may be wise to separate the administration of phosphorus salts from calcium-containing products. In some instances the administration of calcium salts or calcium carbonate is used therapeutically (e.g., uremia) to decrease serum phosphorus levels, so the administration of phosphorus supplements would dynamically counteract the intended use of calcium in these settings, assuming hypophosphatemia is not present. Appropriate calcium-phosphorus ratios in vivo are important for proper calcium homeostasis in tissues and bone; if the serum ionized calcium concentration is elevated, the concomitant use of calcium salts and phosphorus salts may increase the risk of calcium deposition in soft tissue.
    Phosphorus: (Major) High intake of phosphates concomitantly with vitamin D or vitamin D analogs may lead to hyperphosphatemia. Dose adjustment of vitamin D or 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. (Moderate) The oral absorption of phosphorus is reduced by ingestion of pharmacologic doses of calcium carbonate or other phosphate-lowering calcium salts (e.g., calcium acetate). There is, however, no significant interference with phosphorus absorption by oral dietary calcium at intakes within the typical adult range. If the patient requires multiple calcium supplements or a calcium-containing antacid, it may be wise to separate the administration of phosphorus salts from calcium-containing products. In some instances the administration of calcium salts or calcium carbonate is used therapeutically (e.g., uremia) to decrease serum phosphorus levels, so the administration of phosphorus supplements would dynamically counteract the intended use of calcium in these settings, assuming hypophosphatemia is not present. Appropriate calcium-phosphorus ratios in vivo are important for proper calcium homeostasis in tissues and bone; if the serum ionized calcium concentration is elevated, the concomitant use of calcium salts and phosphorus salts may increase the risk of calcium deposition in soft tissue.
    Polyethylene Glycol; Electrolytes; Bisacodyl: (Moderate) By increasing intragastric pH, calcium carbonate can affect the dissolution of oral bisacodyl tablets; administration should be separated by 1 hour.
    Polysaccharide-Iron Complex: (Moderate) Antacids (e.g., calcium carbonate, aluminum hydroxide, or magnesium hydroxide) may decrease the absorption of oral iron preparations (e.g., iron salts or polysaccharide-iron complex). At higher pH values, iron is more readily ionized to its ferric state and is more poorly absorbed. Doses of antacids and iron should be taken as far apart as possible to minimize the potential for interaction.
    Potassium Phosphate: (Moderate) The oral absorption of phosphorus is reduced by ingestion of pharmacologic doses of calcium carbonate or other phosphate-lowering calcium salts (e.g., calcium acetate). There is, however, no significant interference with phosphorus absorption by oral dietary calcium at intakes within the typical adult range. If the patient requires multiple calcium supplements or a calcium-containing antacid, it may be wise to separate the administration of phosphorus salts from calcium-containing products. In some instances the administration of calcium salts or calcium carbonate is used therapeutically (e.g., uremia) to decrease serum phosphorus levels, so the administration of phosphorus supplements would dynamically counteract the intended use of calcium in these settings, assuming hypophosphatemia is not present. Appropriate calcium-phosphorus ratios in vivo are important for proper calcium homeostasis in tissues and bone; if the serum ionized calcium concentration is elevated, the concomitant use of calcium salts and phosphorus salts may increase the risk of calcium deposition in soft tissue.
    Potassium Phosphate; Sodium Phosphate: (Moderate) The oral absorption of phosphorus is reduced by ingestion of pharmacologic doses of calcium carbonate or other phosphate-lowering calcium salts (e.g., calcium acetate). There is, however, no significant interference with phosphorus absorption by oral dietary calcium at intakes within the typical adult range. If the patient requires multiple calcium supplements or a calcium-containing antacid, it may be wise to separate the administration of phosphorus salts from calcium-containing products. In some instances the administration of calcium salts or calcium carbonate is used therapeutically (e.g., uremia) to decrease serum phosphorus levels, so the administration of phosphorus supplements would dynamically counteract the intended use of calcium in these settings, assuming hypophosphatemia is not present. Appropriate calcium-phosphorus ratios in vivo are important for proper calcium homeostasis in tissues and bone; if the serum ionized calcium concentration is elevated, the concomitant use of calcium salts and phosphorus salts may increase the risk of calcium deposition in soft tissue.
    Propantheline: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Propranolol: (Moderate) Antacids may reduce the absorption of propranolol. The need to stagger doses of propranolol has not been established, but may be prudent. Monitor clinical response, and adjust propranolol dosage if needed to attain therapeutic goals.
    Propranolol; Hydrochlorothiazide, HCTZ: (Moderate) Antacids may reduce the absorption of propranolol. The need to stagger doses of propranolol has not been established, but may be prudent. Monitor clinical response, and adjust propranolol dosage if needed to attain therapeutic goals. (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Pseudoephedrine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Pseudoephedrine; Triprolidine: (Minor) It appears that antacids increase pseudoephedrine plasma concentrations. This interaction can be avoided by separating the administration of pseudoephedrine and antacids by 1 to 2 hours. If antacids are used on a regular basis, an alternative to pseudoephedrine may be considered.
    Quinapril; Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Quinidine: (Major) By increasing urinary pH, calcium carbonate can decrease the urinary excretion of quinidine.
    Quinine: (Major) Antacids may delay or decrease the absorption of quinine.
    Raltegravir: (Major) Coadministration of calcium carbonate with raltegravir administered as a once daily dose (high dose regimen) is not recommended. Coadministration may result in decreased plasma concentrations of raltegravir, which may lead to HIV treatment failure or the development of viral resistance. Calcium carbonate may be given with other dosage regimens of raltegravir with no dose adjustments necessary. In a drug interaction study (n = 19), the AUC of raltegravir, given as a single 1200 mg dose, was decreased by 72% (90% CI, 68% to 76%) when administered with a calcium carbonate antacid.
    Relugolix; Estradiol; Norethindrone acetate: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Rifampin: (Moderate) Concomitant use of calcium carbonate and rifampin may decrease the absorption of rifampin. Daily doses of rifampin should be given at least 1 hour before the ingestion of calcium carbonate. (Moderate) Rifampin is a potent inducer of the cytochrome P450 hepatic enzyme system and can decrease the plasma concentrations and possibly the efficacy of cholecalciferol, Vitamin D3. In some cases, reduced concentrations of circulating vitamin D and 1,25-dihydoxy vitamin D have been accompanied by decreased serum calcium and phosphate, and elevated parathyroid hormone. Dosage adjustments of cholecalciferol, Vitamin D3 may be required. (Moderate) Rifampin is a potent inducer of the cytochrome P450 hepatic enzyme system and can decrease the plasma concentrations and possibly the efficacy of ergocalciferol, Vitamin D2. In some cases, reduced concentrations of circulating vitamin D and 1,25-dihydoxy vitamin D have been accompanied by decreased serum calcium and phosphate, and elevated parathyroid hormone. Dosage adjustments of ergocalciferol, Vitamin D2 may be required.
    Rilpivirine: (Moderate) Concurrent administration of rilpivirine and antacids may significantly decrease rilpivirine plasma concentrations, potentially resulting in treatment failure. To decrease the risk of virologic failure, avoid use of antacids for at least 2 hours before and at least 4 hours after administering rilpivirine.
    Riociguat: (Major) Separate administration of riociguat from antacids by at least 1 hour. Antacids such as aluminum hydroxide/magnesium hydroxide decrease riociguat absorption.
    Risedronate: (Moderate) Separate administration of oral risedronate and calcium-containing supplements by at least 2 hours. Calcium will interfere with the absorption of oral risedronate.
    Rosuvastatin: (Moderate) While not specifically reported with calcium carbonate, antacids (aluminum hydroxide; magnesium hydroxide combination) have been shown to reduce rosuvastatin plasma concentrations by 54%. When the antacid is given 2 hours after rosuvastatin, no significant change in rosuvastatin plasma concentrations is observed.
    Rosuvastatin; Ezetimibe: (Moderate) While not specifically reported with calcium carbonate, antacids (aluminum hydroxide; magnesium hydroxide combination) have been shown to reduce rosuvastatin plasma concentrations by 54%. When the antacid is given 2 hours after rosuvastatin, no significant change in rosuvastatin plasma concentrations is observed. (Minor) Antacids (e.g., 20 ml aluminum hydroxide; magnesium hydroxide) have no significant effect on the oral bioavailability of total ezetimibe (ezetimibe plus ezetimibe-glucuronide), ezetimibe-glucuronide, or ezetimibe based on AUC values. However, the peak plasma concentration (Cmax) of total ezetimibe is decreased by 30%. The effect of the antacids in this regard is not expected to have a significant effect on the ability of ezetimibe to lower cholesterol. However, to limit any potential interaction, it would be prudent to administer ezetimibe at least 1 hour before or 2 hours after administering antacids.
    Scopolamine: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Segesterone Acetate; Ethinyl Estradiol: (Minor) Estrogens can increase calcium absorption. Use caution in patients predisposed to hypercalcemia or nephrolithiasis.
    Selpercatinib: (Major) Avoid coadministration of selpercatinib with calcium carbonate due to the risk of decreased selpercatinib exposure which may reduce its efficacy. If concomitant use is unavoidable, take selpercatinib 2 hours before or 2 hours after administration of calcium carbonate. Coadministration with acid-reducing agents decreases selpercatinib plasma concentrations.
    Sodium Ferric Gluconate Complex; ferric pyrophosphate citrate: (Moderate) Antacids (e.g., calcium carbonate, aluminum hydroxide, or magnesium hydroxide) may decrease the absorption of oral iron preparations (e.g., iron salts or polysaccharide-iron complex). At higher pH values, iron is more readily ionized to its ferric state and is more poorly absorbed. Doses of antacids and iron should be taken as far apart as possible to minimize the potential for interaction.
    Sodium Fluoride: (Moderate) Absorption of sodium fluoride may be reduced by concomitant use of antacids that contain magnesium, aluminum, or calcium. An interval of at least 2 hours is advisable between administration of sodium fluoride and antacids.
    Sodium Phosphate Monobasic Monohydrate; Sodium Phosphate Dibasic Anhydrous: (Moderate) The concomitant use of oral sodium phosphate monobasic monohydrate; sodium phosphate dibasic anhydrous preparations in conjunction with antacids containing calcium (e.g., calcium carbonate, calcium salts) may bind the phosphate in the stomach and reduce its absorption. If the patient requires multiple mineral supplements or concurrent use of antacids, it is prudent to separate the administration of sodium phosphate salts from calcium containing products by at least one hour.
    Sodium Polystyrene Sulfonate: (Major) Simultaneous oral administration of cation-donating antacids or laxatives may reduce the potassium exchange capability of sodium polystyrene sulfonate. Examples of cation-donating antacids and laxatives include aluminum hydroxide, calcium carbonate, magnesium carbonate, magnesium citrate, and magnesium hydroxide. Patients who received concomitant oral sodium polystyrene sulfonate and non-absorbable cation-donating antacids and laxatives have developed systemic alkalosis. Intestinal obstruction due to concretions of aluminum hydroxide when used in combination with sodium polystyrene sulfonate has also been reported. One case of grand mal seizure has been reported in a patient with chronic hypocalcemia of renal failure who was given sodium polystyrene with magnesium hydroxide as laxative. Normally, antacids like magnesium hydroxide and calcium carbonate neutralize hydrochloric acid in the stomach, forming magnesium chloride and calcium chloride. As these compounds enter the small intestine, they react with bicarbonate, forming magnesium carbonate and calcium carbonate, which are insoluble. If polystyrene is administered, it blocks this reaction by binding to the magnesium and calcium ions before they can react with the bicarbonate. More hydrogen ions are lost from the stomach than are lost from the intestine, resulting in metabolic alkalosis. Rectal administration of sodium polystyrene sulfonate may reduce the severity of these interactions.
    Sofosbuvir; Velpatasvir: (Moderate) Separate the use of antacids (e.g., calcium carbonate) and sofosbuvir; velpatasvir administration by 4 hours. Velpatasvir solubility decreases as pH increases; therefore, drugs that increase gastric pH are expected to decrease the concentrations of velpatasvir, potentially resulting in loss of antiviral efficacy.
    Sofosbuvir; Velpatasvir; Voxilaprevir: (Moderate) Separate the use of antacids (e.g., calcium carbonate) and sofosbuvir; velpatasvir administration by 4 hours. Velpatasvir solubility decreases as pH increases; therefore, drugs that increase gastric pH are expected to decrease the concentrations of velpatasvir, potentially resulting in loss of antiviral efficacy.
    Sotalol: (Moderate) Coadministration of antacids with sotalol reduces the Cmax and AUC of sotalol by 26% and 20%, respectively. This interaction results in a 25% reduction in the bradycardic effect of sotalol (measured at rest). Administer antacids two hours after the sotalol dose to avoid altering sotalol pharmacokinetics or pharmacodynamics.
    Sotorasib: (Moderate) Avoid coadministration of sotorasib and gastric-reducing agents, such as antacids including calcium carbonate. Coadministration may decrease sotorasib exposure resulting in decreased efficacy. If coadministration with calcium carbonate is necessary, administer sotorasib 4 hours before or 10 hours after calcium carbonate.
    Spironolactone; Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Sucralfate: (Moderate) Oral antacids, including calcium carbonate, potentially interfere with gastric mucosal binding of sucralfate. This interaction can be minimized by staggering the doses of these agents as much as possible.
    Telmisartan; Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Tetracyclines: (Moderate) Divalent or trivalent cations readily chelate with tetracycline antibiotics, forming insoluble compounds. The oral absorption of these antibiotics will be significantly reduced by other orally administered compounds that contain calcium salts, particularly if the time of administration is within 60 minutes of each other. Calcium salts and tetracyclines should not be administered within 1 to 2 hours of each other, although doxycycline chelates less with calcium than other tetracyclines.
    Thiazide diuretics: (Moderate) Dose adjustment of vitamin D or 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 or vitamin D analogs and thiazide diuretics. Thiazide diuretics are known to induce hypercalcemia by reducing the excretion of calcium in the urine. (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Thiothixene: (Major) Antacids may reduce the oral availablility of thiothixene. To avoid this, administer thiothixene at least 1 hour before or 2 hours after the antacid.
    Thyroid hormones: (Moderate) Thyroid hormones should be administered at least 4 hours before or after the ingestion of oral calcium supplements. Calcium salts have been reported to chelate oral thyroid hormones within the GI tract when administered simultaneously, leading to decreased thyroid hormone absorption. Some case reports have described clinical hypothyroidism resulting from coadministration of thyroid hormones with oral calcium supplements.
    Ticlopidine: (Major) Administration of ticlopidine after antacids results in a decrease in plasma levels of ticlopidine. Staggering the times of administration may avoid this pharmacokinetic interaction.
    Tipranavir: (Moderate) Concurrent administration of tipranavir and ritonavir with antacids results in decreased tipranavir concentrations. Administer tipranavir and ritonavir 2 hours before or 1 hour after antacids.
    Triamterene; Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Trihexyphenidyl: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Valproic Acid, Divalproex Sodium: (Minor) Antacids may increase valproic acid AUC. Patients should be monitored for adverse effects in this situation.
    Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) The simultaneous administration of thiazide diuretics and calcium salts or calcium carbonate may lead to hypercalcemia. Thiazides cause a decrease in renal tubular excretion of calcium as well as increase in distal tubular reabsorption. Moderate increases in serum calcium have been seen during the treatment with thiazides; if calcium salts are used concomitantly, careful monitoring of serum calcium in recommended.
    Vitamin A: (Minor) Doses in excess of 1,500 to 2,000 mcg per day of Vitamin A may lead to bone loss and will counteract the effects of supplementation with calcium salts.
    Vitamin D analogs: (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.

    PREGNANCY AND LACTATION

    Pregnancy

    Adverse effects have not been reported with the normal daily intake of Vitamin D within the recommended dietary daily intakes for a pregnant female. Animal reproduction studies have shown fetal abnormalities in several species associated with hypervitaminosis D; therefore, the use of vitamin D in excess of the recommended dietary allowance during normal pregnancy should be avoided unless, in the judgment of the physician, potential benefits outweigh the hazards involved. The RDA of vitamin D during pregnancy is 15 mcg/day (600 International Units/day) with a Tolerable Upper Intake Limit of 100 mcg/day (4,000 International Units/day).

    The 25-hydroxyvitamin D metabolite of vitamin D is distributed into human breast milk at concentrations relative to the maternal serum concentration. Typical breast milk concentrations (without maternal supplementation) are not sufficient to prevent vitamin D deficiency in infants that are exclusively breast-fed and do not receive other vitamin D supplementation. Prolonged, exclusive breast-feeding of infants without recommended vitamin D supplementation is a significant cause of rickets in infants, especially in dark-skinned infants breast-fed by mothers who are not vitamin D replete. Use of vitamin D within the recommended daily dietary intake for lactating women is generally recognized as safe. The recommended maternal daily allowance of vitamin D during breast-feeding is 600 International Units/day with a Tolerable Upper Intake Limit of 4000 International Units/day. While high-dose vitamin D supplementation to nursing mothers has been shown to increase the concentration of vitamin D in breast milk and favorably increase 25(OH)D levels in infants, the results have not been validated and supplementation to infants is still recommended. Generally, the serum calcium concentrations of the infant should be monitored when a nursing mother is prescribed vitamin D in high doses, since hypercalcemia has been reported with high dose maternal use.

    MECHANISM OF ACTION

    Both forms of vitamin D are metabolized to the active form, calcitriol (1,25-dihydroxyvitamin D); all vitamin D activity is due to this metabolite. Calcitriol promotes renal reabsorption of calcium, increases intestinal absorption of calcium and phosphorus, and increases calcium mobilization from bone to plasma. Calcitriol promotes intestinal absorption of calcium through binding to a specific receptor in the mucosal cytoplasm of the intestine. Subsequently, calcium is absorbed through formation of a calcium-binding protein. The synthesis of calcitriol is enhanced by elevated parathyroid hormone levels and low plasma phosphorus levels. Hypocalcemia causes release of parathyroid hormone, which stimulates the production of calcitriol.
    The vitamin D receptor (VDR) is present in numerous tissues throughout the body; the exact action of calcitriol within these tissues is not completely understood. There is evidence that calcitriol plays a role in the immune system. Calcitriol has been shown to inhibit cancer growth and stimulate cell differentiation.

    PHARMACOKINETICS

    Vitamin D is administered orally. Maximal clinical effects of a given dosage are usually observed in 4 weeks. Dietary vitamin D is absorbed from the GI tract in the presence of bile salts and is initially bound to chylomicrons, then is slowly transferred to vitamin D binding protein (DBP) in the serum. The uptake by chylomicrons results in vitamin D update by adipose tissue and muscle; remaining vitamin D in circulation is then metabolized by the liver. The uptake by the liver and other tissues accounts results in a plasma half-life of 4 to 6 hours for supplemental vitamin D. However, studies have shown that the whole-body half-life is about 2 months due to the stores in these tissues.[52879]
     
    Ergocalciferol and cholecalciferol are considered prohormones and are converted in the liver by a group of activating cytochrome P450 (CYP) enzymes, CYP2R1, CYO27A1, and CYP27B1, to 25-hydroxyvitamin D (25(OH)D, calcidiol), the predominant form of vitamin D in the blood. This metabolite has a half-life of about 15 days. Serum 25(OH)D concentrations increase in a non-linear fashion in response to increased vitamin D intake based on baseline concentrations and duration of supplementation. Increasing serum 25(OH)D levels to more than 50 nmol/L requires a greater amount of vitamin D than increasing baseline levels that are less than 50 nmol/L. The impact on serum 25(OH)D concentrations is less when doses are at least 25 mcg/day (1,000 International Units/day) compared to doses less than 25 mcg/day (1,000 International Units/day). For example, for vitamin D doses of at least 25 mcg/day (1,000 International Units/day), the increase in serum 25(OH)D concentrations is about 1 nmol/L for each 1 mcg (40 International Units) of vitamin D. Conversely, for vitamin D doses of 15 mcg (600 International Units) or less, the increase in 25(OH)D concentrations is about 2.3 nmol/L for each 1 mcg (40 International Units) of vitamin D.[52900] In the kidneys, 25-hydroxyvitamin D is further converted to its active, hormonal form, 1,25-dihydroxyvitamin D (1,25(OH)2D, calcitriol), which has a half-life of about 15 hours and accounts for only a small portion of the total body amount of vitamin D. Synthesis to this active form by renal CYP27B1 is tightly regulated by parathyroid hormone and serum phosphate levels.[52879] [52900] All metabolites of vitamin D are excreted through the bile into the feces; very little is excreted in the urine.

    Oral Route

    Vitamin D is well absorbed orally in most individuals without conditions associated with fat malabsorption. There is a time lag of 10 to 24 hours between the oral administration of vitamin D and the initiation of its action in the body due to the necessity of synthesis of the active metabolites in the liver and kidneys.