Clinical pharmacology of antiepileptic drugs 183 patients were on cbz vpa 5 27 than cbz alone 2 27 because vpa increases the cbz e cbz ratio the authors suggested that this effect was due to cbz e but vpa levels were high in the patients as well and may have contributed to the toxicity observed105 because of its inherent variability subtle drug effects on seizure frequency are very difficult to measure. The comprehensive epilepsy center the neurological institute of new york columbia university new york new york usa most of the material contained in this review was presented at the 54th annual meeting of the american academy of neurology and was included in a syllabus prepared for the therapy in neurology course given on april 15 2002. The discussion includes protein binding the role of a major carbamazepine metabolite alterations in pharmacology of aeds in the elderly and aed withdrawal the last topic in particular is a good example of the interaction of pharmacokinetic and pharmacodynamic considerations in explaining the clinical effects of a drug. The clinical pharmacology of traditional antiepileptic drugs despite the availability of newer agents a number of antiepileptic drugs have continued to be employed reasonably widely many years after their introduction to human therapeutics these drugs comprise phenobarbitone and some of its congeners phenytoin ethosuximide carbamazepine