Efficacy and Safety of Risperidone Microspheres for Injection (II) in Patients With Schizophrenia Spectrum Disorders: A Prospective, Single-Arm, Multicenter Real-World Study

Background: Long-acting injectable (LAI) antipsychotics improve adherence and promote long-term recovery in schizophrenia spectrum disorders (SSD). Risperidone Microspheres for Injection (II) (RMI-II), a novel LAI formulation, offers rapid symptom control with a 2-week dosing interval. However, real-world evidence regarding its efficacy and safety remains limited. Methods: A prospective, single-arm, multicenter study was conducted across 15 Chinese research centers. Eligible patients (n = 228) met DSM-5 criteria for SSD, had a Positive and Negative Syndrome Scale (PANSS) total score ≥70, and were followed for 12 weeks. Patients received RMI-II (25–50 mg/2 weeks) via intramuscular injection. Results: Among 228 patients (50.88% male, mean age [37.00 ± 12.82] years) receiving RMI-II, the PANSS total score decreased significantly by 14.02 (3.22, 24.85) at week 2 (p < 0.001) and 38.28 (19.02, 51.34) at week 12 (p < 0.001). At week 2, 37.1% patients achieved clinical response (defined as ≥20% reduction in PANSS total score), and this proportion increased to 83.7% by week 12. By the end of the 12-week treatment, the clinical remission rate (defined as scores ≤3 on PANSS items P1, P2, P3, N1, N4, N6, G5, and G9) was 68.9%. The Clinical Global Impression–Severity Scale score improved from a baseline moderate-to-severe level 5.0 (5.0, 6.0) to a mild-to-moderate level 3.0 (2.0, 4.0). Adverse events occurred in 15.35% of patients, with hyperprolactinemia (1.3%) and extrapyramidal symptoms (1.3%) being most common. Conclusions: RMI-II appeared to be effective and well-tolerated in reducing acute psychotic symptoms. These findings suggest it may represent an additional therapeutic option for SSD. Clinical Trial Registration: No: ChiCTR2200066865, 20 December 2022, https://www.chictr.org.cn/showproj.html?proj=183302.