To report the long-term remission results from the relapse prevention trial (ConstaTRE) in stable patients treated either with risperidone long-acting injectable (RLAI) or the oral atypical antipsychotic quetiapine.

Clinically stable adults with schizophrenia or schizoaffective disorder treated with oral risperidone, olanzapine, or oral conventional antipsychotics were randomized to treatment with RLAI or oral quetiapine. Dosing was according to package-insert recommendation. Efficacy and tolerability were recorded for up to 24 months of treatment. Remission was defined as achieving and maintaining mild or less symptoms of schizophrenia over a 6-month period as defined by Andreasen et al, (2005).

710 patients were randomized (n=355 per group) to either RLAI or quetiapine. Demographics were similar between treatment groups. Relapse occurred in 54 RLAI (16.5%) and 102 quetiapine (31.3%) patients (p< 0.001). Full remission was achieved by 51% RLAI and 39% of quetiapine-treated patients (p=0.003) and was maintained until the end of the trial by 44% of RLAI and 31% of quetiapine patients. Mean duration of full remission was 540.8±181.4 and 508.1±188.0 days for RLAI and quetiapine groups, respectively (p=0.1325). Tolerability was similar between treatment groups. Most adverse events (AEs) were transient. Six RLAI and 10 quetiapine patients discontinued study treatment due to AEs.

Among stable patients with schizophrenia or schizoaffective disorder, remission was more likely to occur in patients switching to RLAI when compared with quetiapine. both RLAI and quetiapine treatments were well tolerated.