Carbamazepine and its 10,11-epoxide metabolite in acute mania: clinical and pharmacokinetic correlates

Abstract

The study was designed to investigate the antimanic profile of carbamazepine as a first-line drug in affective or schizoaffective disorders, to correlate the clinical efficacy with the plasma level of carbamazepine and its 10,11-epoxide metabolite, and to test the potential value of monitoring the salivary level. It was administered alone for 3 weeks to 21 acute manic inpatients. During the first week, the dosage was rapidly increased to 800 mg/day in order to produce steady-state plasma levels of carbamazepine on Day 7. The individual dose was then adjusted to maintain the therapeutic range of 8-12 mg/l. Plasma and saliva levels of the drug and its metabolite, as well as clinical status were assessed weekly. Overall, there was 62% globally improved patients and 77% in affective disorders. The improvement of manic symptoms was significantly lower in schizoaffective than in affective disorders, whereas the dropout rate and the need for antipsychotic medication was higher in the former group. The antimanic response was significantly correlated with the plasma levels both of carbamazepine and its epoxide metabolite, with a time-lag consistent with a delayed drug effect. Drug and metabolite concentrations in saliva were close to their plasma free fraction and were strongly correlated with their plasma levels, suggesting the potential value of salivary drug monitoring.