Valproic Acid [Divalproex sodium; Sodium valproate; Valproate sodium]

Valproic acid pharmacotherapy is indicated for the prophylactic and symptomatic management of simple or complex absence seizures, including petit mal seizures. Valproic acid pharmacotherapy is indicated for the prophylactic management of migraine headache. Valproic acid appears to elicit its anticonvulsant action by means of increasing the availability of GABA, an inhibitory neurotransmitter, within the CNS. However, the exact mechanisms of its anticonvulsant and antimigraine actions have not been determined. Divalproex sodium dissociates in the GI tract into valproic acid, which, in turn, becomes valproate ion. Absorption may be delayed slightly if divalproex sodium is ingested with meals. However, ingesting divalproex sodium with meals does not affect total absorption. Thus, the ingestion of the various oral formulations of divalproex sodium with food, or their substitution with each other, should not be clinically problematic. Valproic acid may decrease the first-pass hepatic metabolism of amitriptyline and inhibit its systemic metabolism. This interaction may result in a significant increase in amitriptyline’s bioavailability.