Calcium Carbonate / Phenytoin
This combination medication pairs the anticonvulsant phenytoin with calcium carbonate supplementation. Phenytoin is used to control various types of seizures, while calcium carbonate addresses phenytoin-induced calcium deficiency. This combination is typically prescribed for patients on long-term phenytoin therapy who require calcium supplementation to prevent or treat hypocalcemia and maintain bone health.
A seizure medication combined with calcium supplementation for patients on long-term anticonvulsant therapy.
Key facts at a glance
- RxNorm
- 1009121
- Generic
- Calcium Carbonate / Phenytoin
- Class
- multi-ingredient
- Brands
- —
- Availability
- rx
- Lactation
- unknown
- Routes
- —
- Forms
- —
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Treatment and prevention of seizures (epilepsy) in patients who require concurrent calcium supplementation due to phenytoin-induced hypocalcemia, osteopenia, or osteoporosis. May also be used for patients with seizure disorders and concurrent calcium deficiency.
Phenytoin works by blocking voltage-gated sodium channels, reducing abnormal electrical activity in the brain that causes seizures. Calcium carbonate provides elemental calcium to counteract phenytoin's interference with calcium absorption and vitamin D metabolism, helping maintain normal serum calcium levels.
Phenytoin significantly reduces calcium and vitamin D absorption; this combination addresses that interaction. Antacids containing calcium may affect phenytoin absorption, so timing of doses is important. Regular monitoring of serum calcium and seizure control is essential. Phenytoin has many drug interactions and requires careful dose adjustment. Do not stop taking phenytoin abruptly.
Official drug label
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This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 28, 2026. · Read our editorial policy