Risperidone long-acting injectable (Risperdal Consta®) for maintenance treatment in patients with bipolar disorder

Poor adherence to pharmacotherapy during maintenance-phase treatment of bipolar disorder is a common occurrence, exposing patients to a high risk of illness relapses, rehospitalization and other negative outcomes. In view of this, there has been a reawakening of interest in the potential of long-acting injectable antipsychotic medications to improve treatment outcome during bipolar maintenance therapy. Indeed, long-acting injectable medications have practical advantages of assuring delivery of medication at a prescribed dose, and perhaps also making it easier to monitor adherence, at least to the long-acting drug. However, there are important limitations to the long-term use of depot typical neuroleptics in patients with bipolar disorder, including risk of extrapyramidal side effects and tardive dyskinesia, which may exceed that of patients with schizophrenia, and the potential for treatment-emergent exacerbation of depressive symptoms. Long-acting injectable risperidone (RLAI) has recently been approved for maintenance treatment in patients with bipolar I disorder. Evidence supporting the use of RLAI for this indication consists of several nonrandomized, open-label studies; one randomized, open-label trial; and two adequately powered randomized, double-blind trials. In general, these studies have shown RLAI to be effective for the prevention of relapse or hospitalization during bipolar maintenance treatment. In the double-blind studies, RLAI was associated with reduced relapse rates, increased time to relapse and greater control of clinical symptoms during maintenance treatment following initial stabilization, compared with oral medication treatment or placebo injection. RLAI appeared to be more effective for preventing manic/mixed episodes than depressive episodes. RLAI showed good tolerability across studies; however, dose-related extrapyramidal effects, sedation, weight gain and prolactin elevation may occur during long-term treatment. Responder-enriched designs and exclusion of important clinical subgroups in the double-blind trials may limit translation of these results to routine care settings.