Risperidone long-acting injection in Schizophrenia Spectrum Illnesses compared to first generation depot antipsychotics in an outpatient setting in Canada

Depot formulations of antipsychotics provide a potential solution to the poor adherence to oral therapies in schizophrenia. However, there have been few comparative studies on the effectiveness and tolerability of first and second generation depot antipsychotics in a real clinical practice setting. The objectives of the present study were to compare safety and outcomes in patients with schizophrenia initiated on risperidone long-acting injection (RLAI) or first generation antipsychotic injections (FGAI) at a Mental Health Centre in British Columbia.

Data were collected by retrospective chart review of all active patients starting depot therapy who were ≥ 18 years of age, had received at least 3 injections of depot antipsychotic and had no prior clozapine treatment. Kaplan Meier survival curves were used to estimate probability of treatment discontinuation and hospitalization.

A total of 70 RLAI and 102 FGAI patient charts were reviewed. At baseline patients in both groups had similar ages (39.7 and 42.7 years for RLAI and FGAI patients (p = 0.09), respectively) but FGAI patients had a longer time since diagnosis (13.6 vs. 9.85 years (p = 0.003)). Treatment retention at 18 months was 77% for RLAI and 86% for FGAI patients (p = 0.22) and 82% and 88% of patients, respectively (p = 0.28), had not been hospitalized. However, RLAI analyses were compromised by lack of long-term patient data. Concomitant medication utilization was similar in both groups except for anticholinergics which were used less frequently in RLAI patients (5.7% vs. 35.3%, p < 0.001). Adverse event frequency was also similar except for extrapyramidal symptoms (EPS) which were more common in FGAI patients (52.9% vs. 17.0% for RLAI (p < 0.001)).

There was no apparent difference in treatment discontinuation or hospitalization between RLAI and FGAI treated patients, although analysis was compromised by low patient numbers. However, decreased EPS with RLAI may offer a significant clinical benefit to patients with schizophrenia.