Efficacy and safety of once-monthly Risperidone ISM in schizophrenic patients with an acute exacerbation.

To evaluate the efficacy and safety of Risperidone ISM against placebo in patients with acute exacerbation of schizophrenia. A multicenter, randomized, double-blind, placebo-controlled study was conducted between June 2017 and December 2018 (NCT03160521). Eligible patients received once-monthly intramuscular injections of Risperidone ISM (75 or 100 mg) or placebo for 12 weeks. The primary efficacy outcome was change in Positive and Negative Syndrome Scale (PANSS) total score from baseline to week 12. The key secondary efficacy outcome was change from baseline in Clinical Global Impressions-Severity of Illness scale (CGI-S) score. Altogether, 438 patients were randomized (1:1:1) and 390 included in the modified ITT efficacy set. The PANSS total score (mean difference, 95% CI) improved significantly from baseline to day 85 with Risperidone ISM 75 and 100 mg, with placebo-adjusted differences of -13.0 (95% CI, -17.3 to -8.8); (p < 0.0001), and -13.3 (-17.6 to -8.9); (p < 0.0001), respectively. Significantly improved mean changes were also obtained for CGI-S score from baseline to day 85 for both doses of Risperidone ISM compared with placebo -0.7 (-1.0 to -0.5); p < 0.0001, for both doses. The statistically significant improvement for both efficacy outcomes were observed as early as 8 days after first injection. The most frequently reported treatment-emergent adverse events were increased blood prolactin (7.8%), headache (7.3%), hyperprolactinemia (5%), and weight increase (4.8%). Neither new nor unexpected relevant safety information was recorded. Risperidone ISM provided rapid and progressive reduction of symptoms in patients with acutely exacerbated schizophrenia without need of oral risperidone supplementation or loading doses. Both doses were safe and well tolerated.