A Randomized, Double-Blind, Multicenter, Noninferiority Study Comparing Paliperidone Palmitate 6-Month Versus the 3-Month Long-Acting Injectable in Patients With Schizophrenia

Background This double-blind (DB), randomized, parallel-group study was designed to evaluate efficacy and safety of paliperidone palmitate 6-month (PP6M) formulation relative to paliperidone palmitate 3-month (PP3M) formulation in patients with schizophrenia. Methods Following screening, patients entered an open-label (OL) maintenance phase and received 1 injection cycle of paliperidone palmitate 1-month (PP1M; 100 or 150 mg eq.) or PP3M (350 or 525 mg eq.). Clinically stable patients were randomized (2:1) to receive PP6M (700 or 1000 mg eq., gluteal injections) or PP3M (350 or 525 mg eq.) in a 12-month DB phase; 2 doses of PP6M (corresponding to doses of PP1M and PP3M) were chosen. Results Overall, 1036 patients were screened, 838 entered the OL phase, and 702 (mean age: 40.8 years) were randomized (PP6M: 478; PP3M: 224); 618 (88.0%) patients completed the DB phase (PP6M: 416 [87.0%]; PP3M: 202 [90.2%]). Relapse rates were PP6M, 7.5% (n = 36) and PP3M, 4.9% (n = 11). The Kaplan-Meier estimate of the difference (95% CI) between treatment groups (PP6M - PP3M) in the percentages of patients who remained relapse free was -2.9% (-6.8%, 1.1%), thus meeting noninferiority criteria (95% CI lower bound is larger than the pre-specified noninferiority margin of -10%). Secondary efficacy endpoints corroborated the primary analysis. Incidences of treatment-emergent adverse events were similar between PP6M (62.1%) and PP3M (58.5%). No new safety concerns emerged. Conclusions The efficacy of a twice-yearly dosing regimen of PP6M was noninferior to that of PP3M in preventing relapse in patients with schizophrenia adequately treated with PP1M or PP3M.