Investigations on the intraindividual constancy of the ratio of carbamazepine to carbamazepine-10,11-epoxide in man.

The constancy of the ratio of carbamazepine (5H-dibenzo[b,f]azepine-5-carboxamide) to carbamazepine-10,11-epoxide was investigated in epileptic patients receiving carbamazepine (Tegretal) monotherapy. We observed a significant interindividual difference, but not between the times in a single patient. Together with the similarly evaluated concordance coefficient, this indicates a certain intraindividual constancy of the ratio between carbamazepine and its epoxide. The carbamazepine:carbamazepine epoxide ratio was dose-dependent, while a sex difference could not be demonstrated.