Olanzapine long-acting injection, discontinuation rates and reasons for discontinuation: 10 years' experience at a UK high-secure hospital.

Background: Olanzapine pamoate has been shown to be an effective second-generation long-acting injection. Its popularity has possibly been adversely affected by the rare incidence of post-injection syndrome (PIS) and the associated requirement to monitor for 3 h after each injection. Objective: This study aimed to collect and present data on the use of olanzapine long-acting injection (OLAI) over a 10-year period in a high-security forensic hospital in South East England. Design: This was a non-interventional retrospective study collecting information from anonymised electronic patient and prescription records. As per hospital Trust guidelines, patient consent to access of hospital records was presumed unless explicitly withdrawn. Method: All patients prescribed OLAI between the years 2009 and 2019 were identified. Data collected included date that OLAI was started, stopped, dose range, side effects and concomitant medication. Results: Of 88 patients who were started OLAI, 45 (51%) continued at month 24. At 60 months, 22 of 70 (31%) patients for whom data were available continued with OLAI. Over 60% of continuers were on higher than recommended doses. Of almost 5000 injections administered, there was 1 episode of PIS. Conclusion: OLAI is an effective treatment for schizophrenia and schizoaffective disorder, especially when used in patients have been able to tolerate the drug and were stabilised on it for 24 months. In over half the patients who continued OLAI, the doses were higher than that recommended by the manufacturer. The incidence of PIS in this study was very low in comparison with other studies. Registration code: 2049.