Background. - Conventional depot antipsychotics can provide constant pharmacologic treatment, eliminating partial compliance and reducing relapse risk. Atypical antipsychotics, have improved clinical profiles but require daily dosing, compromising their overall effectiveness. As oral risperidone provides safety and efficacy benefits over oral haloperidol, improvements may be realized by replacing conventional with atypical agents in long-acting therapy. This report examines 50-weeks of long-acting risperidone therapy in patients previously stabilized with conventional depot antipsychotics.

Methods. - A multi-center, open-label study enrolled 725 patients with schizophrenia or schizoaffective disorder, judged clinically stable and maintained on stable antipsychotic doses for ≥4 weeks. Assignment by clinician judgment to receive 25-75 mg of long-acting risperidone every 2 weeks for 50 weeks followed, with performance of standard safety and efficacy assessments. Data are presented on patients receiving conventional depot antipsychotic monotherapy at study entry.

Results. - In the 188 (25.9%) patients receiving conventional depot antipsychotic monotherapy at entry, mild-to-moderate mean (±S.D.) Positive and Negative Syndrome Scale (PANSS)-total scores improved significantly after receiving long-acting risperidone (64.2 ± 18.9 to 58.2 ± 20.3; P < 0.001). Clinical improvement of ≥20%, 40%, or 60% reduction in PANSS-total score, occurred in 52%, 34%, and 16% of patients, respectively. ESRS subjective ratings and objective physician ratings (Parkinsonism) decreased significantly (P < 0.001).

Conclusion. - Stable patients with mild, residual symptomatology treated with conventional depot antipsychotics experienced significant improvement in psychiatric and movement disorder symptomatology following 1-year of treatment with long-acting risperidone.