Comparative Bioavailability of Risperidone.

This was an open-label, 1-sequence study in patients who are were stable oral risperidone treatment. The study consisted of a screening visit, 1 treatment period with inpatient and outpatient visits, and a Follow-up visit. Patients who were receiving existing oral risperidone treatment (4 mg) continued the oral regimen for 1 week to achieve steady-state concentrations of risperidone (Treatment A). Following the oral risperidone treatment, a single IM dose of 100 mg Risperidone ISM® was administered deeply into the gluteal muscle. A total of 4 IM doses were given, each dose separated by 4 weeks (Treatment B). Safety assessments and PK sampling were performed once each dosing day and each outpatient visit. A final Follow-up visit was conducted to assess each patient for safety and to obtain PK samples. Approximately 80 (with no screening failure) patients were planned for enrolment, with the intent to complete 48 patients with the assumption of an approximate drop-out/not valuable PK rate of 40%. The primary objective of this study was to evaluate the steady-state comparative bioavailability of 100 mg Risperidone ISM® injectable every 4 weeks compared to once-daily 4 mg oral risperidone in patients with schizophrenia stabilized on oral risperidone treatment. The secondary objective of this study was to evaluate the safety and tolerability of 100 mg Risperidone ISM® injectable every 4 weeks compared to once-daily 4 mg oral risperidone in patients with schizophrenia stabilized on oral risperidone treatment.