Pharmacokinetics of carbamazepine in psychiatric patients

Plasma levels of carbamazepine (CBZ) were studied in 10 patients with psychiatric illnesses who were given the drug every 12 hours for 28 days. No correlation has been found between the daily dose of carbamazepine (calculated for body weight) and the steady-state level of the drug. In most patients taking CBZ as the only drug, a 10-20% fall in plasma drug level occurred between the first and second week of treatment, suggesting autoinduction process. A significant correlation was obtained between the plasma level of CBZ measured after the first dose of the drug and the subsequent steady state concentration. This makes possible to predict the steady-state CBZ concentration early in the treatment.