The safety and early efficacy of oral-loaded divalproex versus standard-titration divalproex, lithium, olanzapine, and placebo in the treatment of acute mania associated with bipolar disorder

Background: Previous studies have examined the safety and tolerability of oral-loaded divalproex sodium in the treatment of acute mania, but not the early efficacy of this dosing strategy. The purpose of this study was to evaluate the early efficacy of oral-loaded divalproex. Method: In this pooled analysis, 348 subjects from 3 randomized, double-blind, parallel-group, active- or placebo-controlled studies were used to compare the efficacy, safety, and tolerability of oral-loaded divalproex with standard-titration divalproex, lithium, olanzapine, or placebo. Subjects were inpatients diagnosed with acute mania associated with bipolar I disorder (DSM-III-R or -IV and SADS-Change Version). Patients were administered oral-loaded divalproex (20 or 30 mg/kg/day on days 1 and 2 followed by 20 mg/kg/day, and increased at physician's discretion), standard-titration divalproex initiated at 250 mg t.i.d. and titrated to 40-150 μg/mL, lithium (300 mg t.i.d. initial dose) titrated to 0.4 to 1.5 mEq/L, olanzapine (10 mg q.d. initial dose) up to 20 mg/day, or placebo. Results: The results demonstrate an early efficacy advantage for oral-loaded divalproex compared to standard-titration divalproex at days 5, 7/8, and 10. Efficacy was improved over lithium on day 7/8. There were no efficacy differences between divalproex loading and olanzapine. Divalproex loading showed greater efficacy than placebo at all time points. Divalproex loading was as well tolerated or better tolerated than the other active treatments as measured by adverse events and changes in laboratory parameters. Conclusion: These results suggest the oral loading of divalproex leads to a more rapid antimanic effect when compared with standard-titration divalproex, lithium, or placebo and is better tolerated than olanzapine and as well tolerated as lithium or standard-titration divalproex.