Postinjection delirium/sedation syndrome in patients with schizophrenia receiving olanzapine long-acting injection: results from a large observational study

Background Postinjection delirium/sedation syndrome (PDSS) has been reported uncommonly during treatment with olanzapine long-acting injection (LAI), a sustained-release formulation of olanzapine. Aims The primary aim of the study was to estimate the incidence per injection and per patient of PDSS events in adult patients with schizophrenia who were receiving olanzapine LAI in real-world clinical practice. Secondary aims were to further characterise the clinical presentation of PDSS events, to identify potential risk factors associated with PDSS events and to characterise hospitalisations at baseline and post-baseline. Method A prospective observational study of adult patients with schizophrenia receiving olanzapine LAI from 24 countries. Data were collected on patient characteristics, olanzapine LAI treatment and any adverse events (AEs). All AEs were reviewed and adjudicated for PDSS using predetermined criteria. Results There were 46 confirmed PDSS events (0.044% of the 103 505 injections) in 45 patients (1.17% of the 3858 patients). Based on 45 confirmed events with time-to-onset information, 91.1% (n=41) occurred within 1 h of injection. Time-to-recovery from the event was within 72 h for 95.6% of patients (range 6 h to 11 days). Risk factors for PDSS (per-injection) included high dose (odds ratio (OR)high/low=3.95; P=0.006) and male gender (ORfemale/male=0.42; P=0.017). Conclusions Results of this study confirm previously reported PDSS rates, time to onset and recovery, and the severity of PDSS events, and suggest that higher doses and male gender are potential risk factors associated with PDSS.