This is an open-label, multiple-dose, multicenter study in chronic schizophrenia patients, who are receiving long-acting injectable risperidone 25 or 37.5-mg injections into the gluteal muscle, and clinically require a higher dose. The study consists of a pretreatment screening phase, an 8-week, open label treatment phase during which patients will receive 4 sequential 2 mL injections with long-acting injectable risperidone (37.5 or 50 mg) administered every 2 weeks into the deltoid muscle in alternate arms (right versus left) for each visit; and a post treatment phase consisting of end of study evaluations upon completion of all the study procedures on Day 57 or at early withdrawal. The study hypothesis is that repeated injections of long-acting injectable risperidone into the deltoid muscle will be safe and well tolerated as assessed by the percent of patients who discontinue after at least 2 injections. Safety was assessed using adverse events (including occurrence of extrapyramidal symptoms as assessed by the Extrapyramidal Symptoms Rating Scale), clinical laboratory tests (hematology, serum chemistry, urinalysis, and pregnancy testing), vital signs, physical examinations, electrocardiograms, and injection site evaluation. The patients will receive 4 injections with long-acting injectable risperidone (37.5 or 50 mg) administered as 1 injection every 2 weeks into the deltoid muscle.
