Substitution of immediate-release valproic acid for divalproex sodium for adult psychiatric inpatients.

In a prospective open-label study, the substitution of immediate-release valproic acid for divalproex sodium was evaluated in the treatment of 47 adult psychiatric inpatients who had been stabilized on divalproex for at least one month. After two weeks, no significant change in Clinical Global Impressions scale (CGI) scores or in seizure frequency occurred, and serum valproate concentrations decreased by 14.4 percent (p=.001). One patient was restarted on divalproex because of gastrointestinal complaints. Among the 19 patients remaining hospitalized at six months, mean CGI scores did not significantly change. Costs were reduced 83 percent; annual savings per patient was approximately $905. These preliminary results suggest that many chronic psychiatric inpatients stabilized on divalproex may be safely switched to valproic acid.