To assess the dosing patterns for risperidone long-acting injectable (RLAI) in patients with schizophrenia, participating in the 6-month, open-label Switch to Risperidone Microspheres (StoRMi) trial.

Treatment was initiated at RLAI 25 mg intramuscularly every 2 weeks, although higher (starting) doses were permitted if clinically necessary. Efficacy was evaluated using the Positive and Negative Syndrome Scale (PANSS), Clinical Global Impression (CGI) and Global assessment of functioning (GAF). Treatment-emergent adverse events (AEs) were monitored.

A total of 1,849 patients were included. The mode dose was 25 mg for 52.9% of patients, the remainder evenly distributed among 37.5 and 50 mg doses. At baseline, patients treated with lower RLAI doses were more likely to be female, have shorter disease duration, milder symptoms, and be using less polypharmacy. The strongest predictors that a patient would remain on 25 mg RLAI were baseline PANSS hallucinatory behaviour item (OR = 0.78), baseline CGI (OR = 0.69), gender (OR = 1.56) and country (P< 0.001 for all). Efficacy measures improved for all dosage groups, with the greatest improvement in patients treated with lower doses. AEs were more frequent in patients treated with 50 mg RLAI (68% vs. 57% with lower doses, P<0.0001). Most AEs were mild to moderate in severity.

In this large, European sample, most patients were treated with 25 mg RLAI. Patients treated with lower doses tended to have milder baseline symptoms. Dosing patterns varied among different countries. RLAI was effective and well tolerated over the full range of allowed doses.