Carbamazepine toxicity precipitated by intravenous erythromycin.

The ability of erythromycin to inhibit the hepatic metabolism of carbamazepine causes carbamazepine toxicity. The severity of this drug interaction has been proposed to be related to the dose of erythromycin. The introduction of oral erythromycin produces a two- to fourfold increase in the carbamazepine serum concentration and the resultant toxic manifestations. Carbamazepine toxicity and a more marked increase in carbamazepine serum concentration were observed in a patient treated with intravenous erythromycin.