Pharmacokinetics, safety, and tolerability of paliperidone palmitate 3-month formulation in patients with schizophrenia: A phase-1, single-dose, randomized, open-label study

This multicenter, randomized, open-label, parallel-group, phase-1 study assessed the pharmacokinetics (PK), safety, and tolerability of the investigational intramuscular paliperidone palmitate 3-month (PP3M) formulation in patients with schizophrenia or schizoaffective disorder. A total of 328 patients (men or women, aged 18-65 years) were enrolled in 1 of 4 separately conducted panels (A to D). Each panel had 2 single-dose treatment periods (period 1, 1 mg intramuscular paliperidone immediate release [IR]; period 2, intramuscular PP3M 75-525 mg eq) separated by a washout of 7-21 days. Overall, 245 of 308 (79.5%) PP3M-dosed patients completed the study. Because the PK studies of panels A and C were compromised by incomplete injection in some patients, PK data from only panels B and D are presented. Safety data from all panels are presented. Peak paliperidone plasma concentration was achieved between 23 and 34 days, and apparent half-life was ∼2-4 months. Mean plasma AUC∞ and Cmax of paliperidone appeared to be dose-proportional. Relative bioavailability in comparison with paliperidone was ∼100% independent of the dose and injection site. Headache and nasopharyngitis were the most common (>7%) treatment-emergent adverse events. Overall, safety and tolerability were similar to those of the 1-month formulation. Results support a once-every-3-months dosing interval in patients with schizophrenia or schizoaffective disorder.