Controlled release formulation of divalproex sodium

The present invention relates to pharmaceutical formulations. More particularly, the present invention concerns a formulation comprising valproic acid, a pharmaceutically acceptable salt, ester, or amide thereof, or divalproex sodium, in a controlled release formulation. These controlled release dosage forms have an improved pharmacokinetic profile. These dosage forms minimize the variance between peak and trough plasma levels of valproate, resulting in a reduction in the incidence of side effects. A new oral polymeric controlled release formulation suitable for the once-a-day administration of valproate compounds, such as divalproex sodium, has been discovered. This formulation exhibits significant advantages over the sustained release valproate formulations of the prior art. This formulation minimizes the variation between peak and trough plasma levels of valproate over a 24 hour dosing period. This formulation follows a zero-order release pattern thus producing essentially flat plasma levels of valproate, once steady-state levels have been achieved. This results in a significantly lower incidence of side effects for patients consuming such a formulation.