Dosing patterns in Europe: Efficacy and safety of risperidone long-acting injectable in doses of 25, 37.5 and 50 mg.

Objective. To assess the dose prescription patterns for risperidone long-acting injectable (RLAI) in patients with schizophrenia who participated in the 6-month, open-label Switch to Risperidone Microspheres (StoRMi) trial. Methods. Clinically stable patients requiring a change in medication were converted to RLAI prescribed using clinically-appropriate doses, as determined by treating clinicians. RLAI 25 mg was recommended as the starting dose, although higher initiation doses were permitted if deemed necessary. RLAI was administered intramuscularly every 2 weeks, with dosage adjustments permitted, and continued for a total of 6 months. Efficacy outcomes included Positive and Negative Syndrome Scale (PANSS) and Clinical Global Impression-Severity (CGI-S). Treatment-emergent adverse events (AEs) were monitored. Results. A total of 1,849 patients were included. Modal dose was 25 mg for 52.9% of patients. 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 score (odds ratio [OR]=0.78), baseline CGI-S score (OR=0.69), female gender (OR=1.56), and country of residence (P<0.001 for all). Efficacy measures improved in all dose groups, with the greatest improvement seen in patients treated with lower doses. AEs were more common in patients treated with 50 mg RLAI (68 vs. 57% with lower doses; P<0.0001), although most AEs were mild to moderate in severity. Conclusion. In this study, 25 mg RLAI was the most commonly prescribed dose. RLAI was effective and well tolerated over the full range of doses.