Divalproex sodium extended-release for the prophylaxis of migraine headache.

The Diamond Headache Clinic first began using valproic acid in 1984. Subsequently, a variety of open-label and then placebo-controlled trials were carried out with valproic acid, followed by an enteric-coated formulation known as divalproex sodium delayed-release. These trials demonstrated a consistent pattern of efficacy and the delayed-release form improved tolerability while offering a twice-daily dosing schedule. This led to the development of an extended-release formulation. This formulation further improved tolerability and led to a once-daily dosing. The pivotal trial conducted in patients with migraine with the extended-release formulation demonstrated efficacy similar to that seen with the delayed-release form.