Second-generation long-acting injectable antipsychotic agents: an overview

For over 40 years, antipsychotic drugs have been used as long-term maintenance treatment to control symptoms and reduce relapse rates in patients with schizophrenia. 'First-generation' oral agents such as haloperidol and chlorpromazine are associated with high levels of unwanted neurological effects and poor rates of patient adherence.1,2 Long-acting ('depot') injections of antipsychotics were developed to try to improve adherence. 'Second-generation' antipsychotic agents (also known as atypical antipsychotics) were introduced into clinical practice over 16 years ago. Although these agents have a lower propensity to cause extrapyramidal side effects, they are associated with a range of other unwanted effects (e.g. weight gain and its sequelae).1,3,4 Initially, second-generation agents were only available as orally administered medicines. Three long-acting injectable formulations of second-generation antipsychotics are now available in the UK: olanzapine embonate injection (ZypAdhera), paliperidone injection (Xeplion) and risperidone injection (Risperdal Consta). In this article we review the evidence for these agents and discuss the practical implications of their use.