Measuring plasma levels of carbamazepine. A pharmacokinetic study in patients with affective disorders.

Twenty-four patients suffering from affective disorders, who were being regularly treated with carbamazepine, were studied to determine the course of plasma levels of carbamazepine before (trough levels) and two and four hours after morning intake (peak levels). A large interindividual variation was found between highest peak level and trough level. Despite the lack of systematic studies it is concluded that measuring plasma levels to determine the therapeutic range of carbamazepine should use trough levels, which should provisionally be aimed at between six and eight mg/l. In order to avoid adverse effects, peak levels should not exceed 12 (or even 10) mg/l.