Background: Divalproex sodium has been reported to be better tolerated than valproic acid. To our knowledge, no study has examined whether significant differences in the tolerability and efficacy exist between these preparations in psychiatric patients. The objective of the present study was to compare the tolerability and efficacy of divalproex sodium with those of valproic acid in psychiatric inpatients.
Method: Information gathered retrospectively from the medical records of 150 patients treated with divalproex sodium was compared with that of 150 patients treated with valproic acid. These medical records were photocopied, and any mention of divalproex sodium or valproic acid treatment was concealed. A series of demographic and clinical characteristics were compared.
Results: Patients treated with divalproex sodium compared with patients treated with valproic acid were less likely to have gastrointestinal side effects (14.7% vs. 28.7%, p = .003), specifically anorexia (6.0% vs. 14.7%, p = .012), nausea or vomiting (6.7% vs. 16.7%, p = .007), and dyspepsia (11.3% vs. 22.0%, p = .013). Divalproex sodium-treated patients compared with valproic acid-treated patients were less likely to have discontinued their medication because of side effects (4.0% vs. 12.7%, p = .0066). Twelve (63.2%) of 19 patients who discontinued valproic acid because of gastrointestinal side effects were subsequently treated with divalproex sodium, of whom only 2 continued to have gastrointestinal side effects. There were no differences in efficacy between the 2 drugs.
Conclusion: Divalproex sodium was better tolerated than valproic acid in inpatients with a variety of diagnoses and taking concomitant medications. Patients treated with divalproex sodium compared with patients treated with valproic acid were less likely to experience gastrointestinal side effects and to have discontinued their medication because of an adverse event.