Olanzapine long-acting injection: a review of first experiences of post-injection delirium/sedation syndrome in routine clinical practice

Chris J Bushe, Deborah Falk, Ernie Anand, Marta Casillas, Elena Perrin, Rashna Chhabra-Khanna, Holland C Detke

Olanzapine long-acting injection (LAI) for the treatment of schizophrenia was associated with a cluster of symptoms termed post-injection delirium/sedation syndrome (PDSS) in a small percentage (~2%) of patients during clinical trials. The objective of this analysis was to evaluate the rate and clinical characteristics of PDSS since olanzapine LAI entered commercial use. Cases of PDSS were identified from all reported adverse events during worldwide commercial use of olanzapine LAI through to 1 March 2014. Data sources included two ongoing post-marketing safety studies as well as spontaneously reported adverse events from routine clinical practice over a 5-year period (1 March 2009 to 1 March 2014). A total of 338 PDSS events were identified. Of these, 91% occurred within 1 hour of injection, and 52% of these occurred within 15 minutes. None of the PDSS events in this analysis were fatal, and most resolved within 72 hours. The most common symptoms (occurring in >30% of cases) were sedation (61%), confusion (56%), dysarthria (54%), somnolence (46%), dizziness (45%) and disorientation (35%). Overall, PDSS occurred with approximately 0.07% of injections and in 0.46-1.03% of patients (reporting and incidence rates from spontaneous reports and post-marketing safety studies, respectively). The PDSS events reported during routine clinical use of olanzapine LAI are generally similar in incidence and presentation to those reported in clinical trials. Caution should be applied when interpreting spontaneously reported rates of adverse events, however, due to potential under-reporting. Implemented risk-minimisation activities may contribute substantially to the identification and appropriate management of patients with PDSS in clinical practice.