Evaluate the efficacy and long-term safety of investigational aripiprazole once-monthly (ARI-OM) for maintenance treatment in schizophrenia.

Patients requiring chronic treatment for schizophrenia, not on aripiprazole monotherapy, were cross-titrated from other antipsychotic(s) to aripiprazole in an oral conversion phase (Phase 1). All patients entered an oral aripiprazole stabilization phase (Phase 2). Patients meeting stability criteria entered an ARI-OM stabilization phase (Phase 3), with coadministration of oral aripiprazole for the first 2 weeks. Patients meeting stability criteria were randomized to ARI-OM or placebo once-monthly (placebo-OM) during a 52-week, double-blind maintenance phase (Phase 4). Primary endpoint was time-to-impending relapse. Safety and tolerability were also assessed.

710 patients entered Phase 2, 576 Phase 3 and 403 Phase 4 (ARI-OM=269, placebo-OM=134). The study was terminated early because efficacy was demonstrated by a pre-planned interim analysis. Time-to-impending relapse was significantly delayed with ARI-OM vs. placebo-OM (p< 0.0001, log-rank test). Discontinuations due to treatment-emergent adverse events (AEs) were: Phase 1, 3.8% (n=24/632); Phase 2, 3.0% (n=21/709); Phase 3, 4.9% (n=28/576); Phase 4, 7.1% (n=19/269). Most AEs were mild or moderate. Insomnia was the only AE >5% incidence in any phase. Headache, somnolence, and nausea had a peak first onset within the first 4 weeks of treatment. There were no unusual shifts in all phases in laboratory values, fasting metabolic parameters, weight, or objective scales of movement disorders.

ARI-OM significantly delayed time-to-impending relapse compared with placebo-OM and was well tolerated as maintenance treatment in schizophrenia1.