Hercal (Calcifediol)

Hercal is indicated for individuals with insufficient vitamin D status and for the prevention of bone‑related disorders. It is commonly used to address low serum 25‑hydroxyvitamin D concentrations and to support skeletal health in at‑risk populations.

• Treatment of documented vitamin D deficiency in adults.
• Prevention of osteomalacia in individuals with limited sun exposure.
• Adjunctive support for osteoporosis management alongside calcium and other therapies.
• Maintenance of adequate vitamin D levels during pregnancy and lactation, when advised by a healthcare professional.
• Seasonal supplementation for people living in northern latitudes during winter months.

• Calcifediol, the 25‑hydroxy form of vitamin D3, is absorbed directly from the gastrointestinal tract and bypasses hepatic 25‑hydroxylation. Once in circulation, it binds to vitamin D‑binding protein and is converted in the kidneys to the active hormone calcitriol. Calcitriol then interacts with nuclear vitamin D receptors in target cells, up‑regulating transcription of genes that increase intestinal calcium and phosphate absorption, thereby promoting bone mineralization.

Like other vitamin D analogues, calcifediol may be associated with a range of adverse reactions, most of which are dose‑related and reversible.

Common

• Mild gastrointestinal discomfort such as nausea or abdominal bloating.
• Transient headache or dizziness, especially after initiating therapy.
• Elevated serum calcium levels without symptoms (asymptomatic hypercalcemia).
• Skin rash or mild itching at the site of oral administration (rare).

Serious

• Symptomatic hypercalcemia presenting with polyuria, polydipsia, or cardiac arrhythmia.
• Nephrolithiasis (kidney stone formation) due to sustained high calcium excretion.
• Severe allergic reaction, including angioedema or anaphylaxis.

When using Hercal, certain health conditions and patient factors require careful consideration to minimize risk.

• Patients with a history of hypercalcemia, hyperparathyroidism, or sarcoidosis should avoid excess supplementation.
• Individuals with renal impairment may have reduced ability to excrete calcium and should be monitored.
• Pregnant or breastfeeding women should consult a healthcare professional before initiating therapy.
• Concomitant use of high‑dose calcium supplements can increase the risk of hypercalcemia.
• Routine monitoring of serum 25‑hydroxyvitamin D and calcium levels is recommended during long‑term use.
• Elderly patients, especially those with limited mobility, may benefit from periodic bone density assessment.

Calcifediol can affect the pharmacokinetics or pharmacodynamics of several medicines; awareness of these interactions helps ensure safe co‑administration.

Avoid

• Thiazide diuretics, which can potentiate hypercalcemia when combined with vitamin D analogues.
• High‑dose vitamin A or retinoid therapy, increasing the risk of hypercalcemia.
• Certain antacids containing aluminum or magnesium, which may reduce calcifediol absorption.
• Orlistat, which can decrease the absorption of fat‑soluble vitamins including calcifediol.

Use with caution

• Loop diuretics, as they may alter calcium balance and require monitoring.
• Corticosteroids, which can diminish vitamin D effectiveness and necessitate dose adjustment.
• Anticonvulsants such as phenytoin or phenobarbital, which accelerate vitamin D metabolism.
• Bisphosphonates, because concurrent use may affect calcium homeostasis and bone turnover.