Abstract

A long-acting form of the second-generation antipsychotic drug risperidone is now broadly available for the treatment of schizophrenia and closely related psychiatric conditions. It combines the advantage of previously available depot formulations for first-generation drugs with the favorable characteristics of the modern "atypical" antipsychotics, namely higher efficacy in the treatment of the negative symptoms of schizophrenia and reduced motor disturbances. Published clinical studies show an objective clinical efficacy (as per psychiatric symptom scores and relapse data) that exceeds that of oral atypical antipsychotics when patients are switched to the long-acting injectable form, a low incidence of treatment-emergent extrapyramidal side effects, and very good acceptance by patients. Available data for maintenance treatment of bipolar disorder show equivalence with the oral form instead of superiority, but are still limited. As it seems likely that efficacy benefits are mostly due to the fact that the injectable form reduces the demand for patient compliance to one physician visit every 2 weeks instead of self-administration on a daily or twice-daily basis, additional potential could exist in other psychiatric disorders where atypical antipsychotic drugs are of benefit but where patient adherence to treatment schedules is typically low.