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

Abstract Background Several different formulations of valproic acid derivatives are available in the United States. Although these have absorption characteristics, they believed to be interchangeable, with exception extended-release product. Case Report A 31-year-old African American man schizoaffective disorder was started on fluphenazine concentrate and valproate oral solution admission an inpatient unit. 12-hour steady-state concentration, drawn 1000 mg/day, resulted 40.8 mg/L, dose continued titrated. Despite increasing doses, confirmed medication adherence, accurate lab sampling, his concentrations remained low: 60.3 60.1 mg/L 1500 65.6 1750 mg/day. He switched divalproex delayed-release tablets, increased 2000 Follow-up were significantly higher, at 126.6 113.8 mg/L. It is theorized that formulation divalproex/valproic what contributed differences concentrations. Discussion Valproic considered several studies demonstrated chronic psychiatric inpatients stabilized may safely without changes stability. This case demonstrates a significant difference serum drug when switching from tablets.