DRISDOL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for DRISDOL (DRISDOL).
Drisdol (ergocalciferol) is a vitamin D2 analog that increases intestinal absorption of calcium and phosphate, promotes renal tubular reabsorption of calcium, and stimulates bone mineralization by binding to vitamin D receptors, which regulate gene expression.
| Metabolism | Hepatic via CYP27A1 to 25-hydroxyergocalciferol; further renal metabolism via CYP27B1 to active form; undergoes enterohepatic recycling. |
| Excretion | Primarily excreted via bile into feces (~90%), with renal excretion accounting for the remainder (~10%). Biliary excretion of metabolites is the major route, with enterohepatic recycling contributing to prolonged elimination. |
| Half-life | Terminal elimination half-life is approximately 19–48 hours after a single oral dose, with clinical context: repetitive dosing increases half-life due to accumulation in adipose tissue, leading to a functional half-life of weeks to months for vitamin D stores. |
| Protein binding | Approximately 90–95% bound to alpha globulins, specifically vitamin D-binding protein (DBP), and to a lesser extent albumin. |
| Volume of Distribution | Volume of distribution is approximately 0.6–0.8 L/kg, reflecting extensive distribution into body tissues, including adipose tissue and liver, where it accumulates. |
| Bioavailability | Oral: Well absorbed, with bioavailability estimated at 60–80% in the presence of adequate bile salts and fat; sublingual and IM routes achieve similar systemic availability, though IM may be variable due to injection site factors. |
| Onset of Action | Oral: Delayed, typically 2–5 days for rise in serum 25-hydroxyvitamin D levels; clinical effects on calcium absorption may take 7–14 days. Intramuscular: Similar, but with depot effect prolonging onset. |
| Duration of Action | Oral: Duration of effect on calcium metabolism lasts 2–4 weeks after single dose, but serum 25(OH)D levels may remain elevated for months. IM: Effect can persist for 1–2 months due to slow release from injection site. |
| Molecular Weight | 384.64 |
50,000 IU orally once weekly for 8 weeks, then 50,000 IU orally once monthly for maintenance.
| Dosage form | CAPSULE |
| Renal impairment | No specific dose adjustment required for renal impairment; monitor serum calcium and phosphate levels in severe renal disease. |
| Liver impairment | No specific adjustment for Child-Pugh class A or B; use with caution and monitor vitamin D levels in Child-Pugh class C. |
| Pediatric use | For vitamin D deficiency: 600-1000 IU daily for infants <1 year; 1000-2000 IU daily for children 1-18 years, or 50,000 IU once weekly for 6-8 weeks for children ≥12 years. |
| Geriatric use | No specific dose adjustment; monitor serum calcium and 25-hydroxyvitamin D levels regularly due to age-related changes in metabolism and higher risk of hypercalcemia. |
| 1st trimester | Caution: Vitamin D is essential but high doses may be teratogenic; recommended daily allowance (RDA) 600 IU/day; toxicity rare with normal doses. |
| 2nd trimester | Doses up to 4000 IU/day are considered safe; higher doses should be avoided unless treating deficiency. |
| 3rd trimester | Same as t2; monitor serum calcium if using high doses. |
Clinical note
Comprehensive clinical and safety monograph for DRISDOL (DRISDOL).
| Placental transfer | Crosses placenta; fetal levels correlate with maternal; important for fetal bone development. |
| Breastfeeding | Vitamin D and its metabolites are excreted in breast milk in small amounts; supplementation of mother with up to 4000 IU/day is safe; monitor infant for hypercalcemia if maternal doses are high. |
■ FDA Black Box Warning
None.
| Serious Effects |
HypercalcemiaVitamin D toxicityMalabsorption syndrome
| Precautions | Hypercalcemia risk, especially in renal impairment, Monitor serum calcium and phosphate levels, Use with caution in patients with sarcoidosis or other granulomatous diseases due to increased vitamin D sensitivity, Avoid use in patients with hypervitaminosis D or malabsorption syndrome |
| Food/Dietary | No significant food interactions; however, vitamin D is fat-soluble, so absorption may be enhanced with fatty meals. Avoid excessive intake of calcium-rich foods (e.g., dairy) during high-dose therapy to prevent hypercalcemia. |
| Clinical Pearls |
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| Lactation Rating |
| L2 (Safer) |
| Teratogenic Risk | FDA Pregnancy Category A. No evidence of teratogenicity in human studies at recommended doses. Hypercalcemia due to excessive vitamin D intake during pregnancy may lead to fetal abnormalities including supravalvular aortic stenosis, elfin facies, and intellectual disability. Risk is dose-dependent and primarily associated with maternal hypercalcemia, not standard supplementation. |
| Fetal Monitoring | Monitor serum calcium, phosphate, and 25-hydroxyvitamin D levels periodically. Assess for signs of vitamin D deficiency or toxicity. In cases of high-dose therapy, monitor maternal and neonatal calcium levels. |
| Fertility Effects | No adverse effects on fertility reported at standard doses. Vitamin D deficiency may impair fertility in both females and males; supplementation to correct deficiency may improve reproductive outcomes. |
| Drisdol (ergocalciferol) is vitamin D2; for treating vitamin D deficiency, use high-dose repletion protocols (e.g., 50,000 IU weekly for 8 weeks) then switch to maintenance. Monitor serum 25(OH)D and calcium levels periodically to avoid toxicity. In renal failure, consider using calcitriol instead due to impaired 1α-hydroxylation. |
| Patient Advice | Take exactly as prescribed; do not take extra doses. · Notify your doctor if you have symptoms of high calcium: nausea, vomiting, constipation, weakness, or confusion. · Do not take with other vitamin D supplements or calcium-containing products without medical advice. · Store at room temperature away from light and moisture. |