Vitamin D3

What it is and how it works

Colecalciferol is hydroxylated in the liver to calcifediol and in the kidney to calcitriol, the active hormone that increases intestinal absorption of calcium and phosphate and regulates bone mineralisation and parathyroid hormone secretion.

Indications

Prevention and treatment of vitamin D deficiency and insufficiency; adjunct in the prevention and treatment of osteoporosis in patients with, or at risk of, vitamin D deficiency; rickets and osteomalacia due to deficiency.

Dosage and administration (summary)

High-strength products (such as 50,000 IU capsules or 300,000 IU injections) are used for treatment of established deficiency at intervals (for example weekly, monthly or as a single loading dose) set according to the measured 25-hydroxyvitamin D level and national guidance, followed by a lower maintenance dose. Daily maintenance doses are generally 400–2000 IU.

Contraindications

Hypercalcaemia or hypercalciuria, vitamin D toxicity, calcium-containing kidney stones, and severe renal impairment (where calcitriol or an active analogue is preferred).

Warnings and precautions

Excessive or prolonged high doses can cause hypercalcaemia (nausea, thirst, polyuria, confusion, renal impairment); monitor serum calcium during high-dose or long-term treatment, and in sarcoidosis, renal impairment or with thiazide diuretics or digoxin. Account for vitamin D from other sources.

Pregnancy

Recommended doses for deficiency are used in pregnancy; high-dose regimens only on specialist advice, as overdose may harm the fetus.

Storage and supply

Store below 25 °C, protected from light.

Source: reference summary prepared from the EU SmPC/EPAR, BNF and WHO Model Formulary. The approved product information in Iran governs.