Long-Acting Injectable Risperidone: Efficacy and Safety of the First Long-Acting Atypical Antipsychotic

OBJECTIVE: The authors assessed the efficacy and safety of the first long-acting atypical antipsychotic (long-acting injectable risperidone) in patients with schizophrenia. METHOD: In a 12-week, multicenter, double-blind, randomized study, patients received intramuscular injections every 2 weeks of placebo or long-acting risperidone (25 mg, 50 mg, or 75 mg). The primary measure of efficacy was the change in total score on the Positive and Negative Syndrome Scale. RESULTS: Of the 554 patients who were enrolled, 400 entered the double-blind study, and 370 received at least one postbaseline assessment. Mean changes in score of -6.2, -8.5, and -7.4 on the Positive and Negative Syndrome Scale were seen at endpoint for the 25-, 50-, and 75-mg risperidone groups, respectively; all three change scores were significantly different from that seen with placebo (+2.6). Improvements in positive and negative symptoms were also significantly greater in patients receiving risperidone. Long-acting risperidone was well tolerated. Adverse events related to extrapyramidal symptoms were spontaneously reported by 13% of patients receiving placebo and 10% of patients in the 25-mg risperidone group, with higher rates in the 50-mg and 75-mg groups. Severity of extrapyramidal symptoms was mild at baseline and throughout the trial in each treatment group. Mean weight changes were small in the 25-, 50-, and 75-mg risperidone groups (0.5 kg, 1.2 kg, and 1.9 kg, respectively). Injection site pain was rated as low by the patients, consistent with the investigators' pain ratings. CONCLUSIONS: Long-acting injectable risperidone was efficacious and well tolerated and provides both clinicians and patients with a new mode of treatment that can improve the outcome of long-term therapy.