An Open-Label, One-Sequence Study to Evaluate the Steady-State Comparative Bioavailability of Intramuscular Risperidone ISM® and Oral Risperidone

This is an open-label, 1-sequence study in subjects who are on stable oral risperidone treatment. The study consists of a screening visit, 1 treatment period with inpatient and outpatient visits, and a follow-up visit.

Subjects who are on existing oral risperidone treatment (4 mg) will continue the oral regimen for 1 week to achieve steady-state concentrations of risperidone. Following the oral risperidone treatment, a single intramuscular (IM) dose of 100 mg risperidone ISM® will be administered deeply into the gluteal muscle. A total of 4 IM doses will be given that will be separated by 4 weeks.

Safety assessments and pharmacokinetic (PK) sampling will be performed on each dosing day and each outpatient visit. A final follow-up visit will take place to assess each subject for safety and to obtain PK samples.

Approximately 58 subjects will be enrolled, with the intent to complete 41 subjects. Fifty-eight subjects were estimated for enrollment based on 41 completers assuming an approximate drop-out rate of 30%.

The primary objective of this study is 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 subjects with schizophrenia stabilized on oral risperidone treatment.