INTERACTION BETWEEN CARBAMAZEPINE AND BROMPERIDOL

Objective. The interaction between carbamazepine and bromperidol was s tudied in 13 schizophrenic inpatients. Methods: Before carbamazepine a ddition, the subjects were taking bromperidol 12-24 mg.day(-1) for 1-2 0 weeks. Carbamazepine 400 mg.day(-1) was coadministered for 4 weeks, and blood samplings were performed before carbamazepine addition and a t weekly intervals after the addition. Plasma concentrations of brompe ridol and its reduced metabolite were measured by highperformance liqu id chromatography. Results: Carbamazepine significantly decreased plas ma concentrations of both bromperidol and reduced bromperidol for all weeks. On average, the plasma concentrations of bromperidol and reduce d bromperidol at 4 weeks were 37% and 23% of the corresponding precarb amazepine values. Despite these decreases in plasma concentration, the Clinical Global Impression scores decreased slightly but significantl y after carbamazepine addition. Conclusion: The present study suggests that carbamazepine decreases plasma concentrations of bromperidol and its reduced metabolite by inducing the metabolism of these compounds. Nevertheless, adjunctive carbamazepine may be useful for schizophreni c patients treated with bromperidol.