THE PHARMACOLOGICAL ACTIVITY OF OXCARBAZEPINE IS PRIMARILY EXERTED THROUGH THE 10-MONOHYDROXY METABOLITE (MHD) OF OXCARBAZEPINE. THE PRECISE MECHANISM BY WHICH OXCARBAZEPINE AND MHD EXERT THEIR ANTISEIZURE EFFECT IS UNKNOWN; HOWEVER, IN VITRO ELECTROPHYSIOLOGICAL STUDIES INDICATE THAT THEY PRODUCE BLOCKADE OF VOLTAGE-SENSITIVE SODIUM CHANNELS, RESULTING IN STABILIZATION OF HYPEREXCITED NEURAL MEMBRANES, INHIBITION OF REPETITIVE NEURONAL FIRING, AND DIMINUTION OF PROPAGATION OF SYNAPTIC IMPULSES.