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Interactions between prim done, carbamazepine, and nicotinamide

1982; Lippincott Williams & Wilkins; Volume: 32; Issue: 10 Linguagem: Inglês

10.1212/wnl.32.10.1122

1526-632X

Blaise F. D. Bourgeois, W. E. Dodson, James A. Ferrendelli,

Pharmacological Receptor Mechanisms and Effects

The effect of nicotinamide on the conversion of primidone to phenobarbital was0 studied in mice and in three epileptic patients. In mice, 200 mg per kilogram of nicotinamide increased the half-life of primidone by 47.6%, and the conversion to phenobarbital and phenylethylmalonamide was decreased by 32.4% and 14.5%, respectively. Nicotinamide also decreased the conversion of primidone to phenobarbital in patients. The dose of nicotinamide correlated directly with the primidone:phenobarbital ratio (r = 0.861, p < 0.01). Nicotinamide also increased carbamazepine levels in two patients treated with this drug. The data demonstrate that nicotinamide inhibits metabolism of primidone in mice and metabolism of primidone and carbamazepine in humans. This probably occurs by inhibition of cytochrome P-450 by nicotinamide.