Bioavailability of two carbamazepine preparations during chronic administration to epileptic patients

Two preparations of carbamazepine, as tablets and in syrup, were given for 8 weeks to 20 patients with epilepsy in a randomized crossover study. Weekly plasma levels were 3-21 mg/1 on dosages of 5-24 mg/kg/day. There was no difference in absorption or steady-state level between the two preparations. Carbamazepine 10, 11-oxide was constantly present when the level of carbamazepine was over 5 mg/l, and tended to be lower with the syrup.