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Using an open substitution study design, conventional carbamazepine (Tegretol, CBZ-C and a chewable carbamazepine formulation (Tegretol Chewtabs, CBZ-CHEW) were compared in 12 patients with severe intractable epilepsy. During a dosing interval, no significant differences were observed with respect to trough or peak serum concentrations of CBZ and CBZ-10,11-epoxide (CBZ-E), the active metabolite. The area under the serum CBZ concentration-time curve for a dosing interval was (mean +/− s.e. mean) 146 +/− 10 mumols l-1 h on CBZ- C and 143 +/− 9 mumols l-1 h on CBZ-CHEW. The two formulations, therefore, have a similar pharmacokinetic profile and could be used interchangeably in the management of patients with epilepsy. [ABSTRACT FROM AUTHOR]

1. Antipyrine (AP) clearance, half-life and volume of distribution were determined in 52 patients, taking one or more antiepileptic drug (AED), before and 4 weeks after the complete removal of phenytoin (PHT, n = 20), carbamazepine (CBZ, n = 15) and sodium valproate (VPA, n = 17). 2. PHT removal was associated with a mean 13% fall in AP clearance and a mean 16% increase in AP half-life, in patients who were also taking CBZ with or without barbiturates. There was no significant difference between patients who did, and did not, take barbiturates, in addition to CBZ. 3. CBZ removal was associated with a mean 45% fall in AP clearance and a mean 69% increase in AP half-life, if there was no inducing AED comedication, but had no effect on AP clearance and half- life if PHT and/or barbiturates were also being taken. 4. Removal of VPA had no effect on AP clearance or half-life. 5. The removal of PHT, CBZ and VPA had no significant effect on AP volume of distribution. 6. PHT appears to be a more powerful inducer of hepatic enzyme activity, as measured by the AP test, than is CBZ. [ABSTRACT FROM AUTHOR]