Pharmacokinetic evaluation of novel sustained‐release dosage forms of valproic acid in humans

1. Five new sustained‐release dosage forms of valproic acid (VPA) were developed. 2. The new sustained‐release formulations were administered to six healthy subjects for comparison with a standard tablet and an i.v. preparation of the drug. 3. Three of the formulations exhibited a more prolonged and uniform absorption rate and yielded more sustained serum levels after ingestion. These three formulations maintained serum therapeutic levels of VPA for 24 h after a single oral administration of 1 g, and were bioequivalent to a marketed standard tablet of VPA. 4. The absorption profile of the various oral formulations was analysed pharmacokinetically, using the Loo‐Riegelman procedure.