Multicenter Bioavailability Study of Long-Acting Paliperidone in Patients With Schizophrenia or Schizoaffective Disorder.

Purpose/background: Schizophrenia is often associated with nonadherence to oral antipsychotic therapy, which increases the risk of relapse, hospitalization, and higher health care costs. To overcome this challenge, long-acting injectable (LAI) antipsychotics, such as paliperidone palmitate, offer a solution by reducing relapse rates. Also, the bioequivalent formulations can enhance treatment accessibility while maintaining efficacy and safety. The present study assessed the bioequivalence of a test paliperidone palmitate extended-release injectable suspension (PP-ERIS), Vegapali, compared with the reference formulation, Invega Sustenna.

Methods/procedures: A multicenter, randomized, multiple-dose, open-label, parallel-arm pharmacokinetic (PK) study was conducted including patients with schizophrenia or schizoaffective disorder receiving monthly intramuscular injections of the test or reference formulation for 7 months. Plasma samples were collected predose and postdose to determine steady-state PK parameters, including C max,ss and AUC τ,ss . The bioequivalence was confirmed if the 90% CIs for the test/reference geometric mean ratios were within 80.00% to 125.00%. Safety assessments also included adverse event (AE) monitoring and clinical evaluations.

Findings/results: The PK analysis demonstrated that the 90% CIs for Cmax,ss and AUCτ,ss were within the required bioequivalence range. Both formulations exhibited comparable systemic exposure, and AE incidence was consistent with the known safety profile of paliperidone palmitate.

Implications/conclusions: The test formulation, Vegapali, proved to be bioequivalent to the reference product, supporting its use as an alternative LAI treatment for schizophrenia. This finding guarantees the therapeutic equivalence of both formulations, expanding access to effective and sustained treatment options for schizophrenia management.