A depot injection is given via a long-lasting injection and aims to promote compliance in people with particularly severe mental illness, thereby enhancing relapse prevention. Risperidone is the first second-generation antipsychotic to be available in a depot format. The effects of this form of the drug have been extensively studied in trials prior to its introduction but the kinds of people who might take it have not. A Dutch study, using dispensing data from 53 community pharmacies in the north-east of the Netherlands looked to see what kind of chronic antipsychotic users switched to long-acting Risperidone. They found that the predictors for switching from an oral to a depot form of drugs were: being a man, a previous use of depot antipsychotics, recent anticholinergic drug use, and a gap in 'antipsychotic dispensation history,' i.e. a patchy history of drug-taking. Predictors of switching to depot Risperidone from a depot first-generation antipsychotic were previous use of a depot antipsychotic and consulting a specialist. The researchers concluded that compared with oral antipsychotics service users receiving a depot injection were likely to be less compliant and to suffer from worse side effects. People receiving depot risperidone as opposed to a depot first-generation antipsychotic tended to be more severely ill. The researchers concluded that the long-lasting risperidone was being used for the most severely-ill people; something that will need to be borne in mind when assessing its effectiveness.
Vehof, Jelle ... [et al] - Predictors for starting depot administration of risperidone in chronic users of antipsychotics Journal of Clinical Psychopharmacology December 2008, 28(6), 625-630