Schizophrenia relapse and the clinical usefulness of once-monthly aripiprazole depot injection

Abstract

Improving medication adherence is critical to improving outcomes in patients with schizophrenia. A long-acting injectable (depot) antipsychotic is one of the most effective methods for improving treatment adherence and decreasing rehospitalization rates in patients with schizophrenia. Until recently, only three second-generation antipsychotics were available in a long-acting injectable formulation (risperidone, paliperidone, and olanzapine). In this respect, the emergence of long-acting aripiprazole injection (ALAI), approved by the US Food and Drug Administration for the treatment of schizophrenia in 2013, is timely. ALAI is a lyophilized powder of aripiprazole, and the aripiprazole molecule is unmodified. The initial and target dosage of ALAI is 400 mg once monthly, but it could be reduced to 300 mg if adverse reactions occur with 400 mg. When first administering ALAI, it is recommended to continue treatment with oral aripiprazole (10-20 mg/day) or another oral antipsychotic for 2 weeks in order to maintain therapeutic antipsychotic concentrations. The primary clearance route for ALAI is hepatic, ie, cytochrome P450 (CYP) 2D6 and CYP3A4, so dose adjustment is required in poor CYP2D6 metabolizers. The efficacy of ALAI was demonstrated in three studies. A randomized controlled trial that formed the basis for approval of ALAI in the treatment of schizophrenia showed that ALAI significantly delayed time to impending relapse when compared with placebo (P<0.0001, log-rank test). An open-label, mirror study demonstrated that total psychiatric hospitalization rates were significantly lower after switching from oral antipsychotics to ALAI. Another randomized controlled trial presented in poster form suggested that ALAI 400 mg was comparable with oral aripiprazole 10-30 mg in preventing relapse. ALAI was generally well tolerated during both short-term and long-term studies. Its tolerability profile, including extrapyramidal symptoms and clinically relevant metabolic parameters, was similar to placebo. However, insomnia, headache, anxiety, akathisia, weight gain, injection site pain, and tremor need clinical attention. These studies suggest that ALAI is a viable treatment option for patients with schizophrenia, but direct head-to-head comparisons between ALAI and other long-acting injectable antipsychotics are needed to elucidate its risk-benefit profile.