Ergocalciferol
DRISDOL
What it isVitamin D2 precursor requiring hepatic and renal activation; prescribed for rickets, hypoparathyroidism and deficiency.
Why this oneIt is the traditional prescription repletion form, but D3 generally raises and sustains vitamin D more effectively.
What limits itIt cannot be fully activated in advanced kidney failure; excess causes hypercalcemia. Calcitriol bypasses renal activation.
FDA-approved for
- hypoparathyroidism, refractory rickets and familial hypophosphatemia
Off-label
- vitamin D deficiency repletion (the common real-world use)
FDA label
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| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Vitamin D-resistant rickets | all | 12,000 IU daily | 12,000–500,000 IU daily | 500,000 IU daily |
| Hypoparathyroidism | all | 50,000 IU daily | 50,000–200,000 IU daily with calcium lactate 4 g six times daily | 200,000 IU daily |
Renal Undefined
Hepatic Undefined
Narrow range between therapeutic and toxic doses — individualize carefully.
Instructions
- Individualize dose under close medical supervision
- Ensure adequate calcium intake
- Monitor blood calcium and phosphorus every 2 weeks (or more often)
- Obtain bone X-rays monthly until condition is corrected and stabilized
Contraindications
- Hypercalcemia
- Malabsorption syndrome
- Abnormal sensitivity to the toxic effects of vitamin D
- Hypervitaminosis D
Cautions
- Hypervitaminosis D / vitamin D toxicity — narrow therapeutic index; monitor serum calcium and phosphorus
Adverse reactions
- Hypercalcemia/hypervitaminosis D: renal impairment (polyuria, nocturia, hypercalciuria, nephrocalcinosis, azotemia)
- Soft-tissue and vascular calcification
- Nausea, anorexia, constipation
- Weight loss, weakness, bone demineralization
Pregnancy Category C; avoid amounts exceeding the RDA (excess vitamin D associated with fetal abnormalities); safety above 400 IU/day not established.
Lactation Undefined
NO BOXED WARNINGS
Principal riskHypercalcemia with excessive dosing
Cost, est. cash$5–$150/month
Generic entry2009
Classes and tags
Clinical profile
Legacy pregnancy categoryUnknown / historical label unavailable
Defining liabilityUsually well tolerated at replacement doses; excessive dosing can cause agent-specific metabolic or organ toxicity.
Active metabolites
Mechanism of action: Ergocalciferol ballicule
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