Differences in serum concentration with valproate oral solution versus delayed-release divalproex in an adherent patient.

Valproic acid formulations are considered to be interchangeable, and several studies have demonstrated that chronic psychiatric inpatients stabilized on delayed-release divalproex may be safely switched to valproate oral solution without changes in psychiatric stability. This case demonstrates a significant difference in serum drug concentrations when switching from valproate oral solution to divalproex delayed-release tablets.