Ergocalciferol

DRISDOL

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Pronunciation: er-goe-kal-SIF-er-ol

Ergocalciferol ballicule: receptor binding, kinetics and half-life diagram — Mechanism of action: Ergocalciferol ballicule

Ergocalciferol mascot mnemonic cartoon — Visual mnemonic: Ergocalciferol mascot
**“2 Ergonomic D’s”**

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.

Ergocalciferol molecular structure (skeletal formula) — Molecular structure: Ergocalciferol

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

Available strengths

cap 50,000 IU

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

Cost

Ergocalciferol (DRISDOL)

Strength		#/mo	generic $/mo	CostPlus
50000 IU	cap	30 qd		not offered

NADAC is a voluntary CMS survey of what retail community pharmacies pay for the drugs they stock. Ergocalciferol is dispensed outside retail pharmacies, so it rarely appears on surveyed invoices.

Generic entry2009

NO BOXED WARNINGS

Principal riskHypercalcemia with excessive dosing

Classes and tags

Clinical profile

Therapeutic safety burden1 / 4

Overdose danger1 / 4

Weight-gain liability0 / 4

Sedation liability0 / 4

QT / Torsades0 / 4

Direct muscarinic antagonism0 / 4

Embryofetal risk1 / 4

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

Calcifediol

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