ABSTRACT
This chapter considers the antiepileptic action of the hydantoins. It focuses on phenytoin and those interested in the other hydantoins should refer to M. A. Rogawski and R. J. Porter, or H. J. Kupferberg for more information. Phenytoin has several well known effects on Norepinephrine neurotransmission, but the extent to which these play a role in the antiepileptic action of this drug is unclear. Phenytoin has long been known to elevate brain levels of 5-hydroxytryptamine (5-HT) in rats. Phenytoin has been shown to increase the synthesis of 5-HT and to enhance the behavioral effects of 5-HT agonists in rats and to increase the cerebral spinal fluid levels of 5-hydroxyindoleacetic acid of patients. Phenytoin has been shown to increase the action of Gamma Aminobutyric Acid (GABA) and may under some circumstances increase the concentration of GABA, although in some regions of brain the concentration may actually be decreased.
