ZypAdhera ® (olanzapine pamoate monohydrate)

ZypAdhera® (olanzapine pamoate): Incidence of Post Injection Syndrome

The post injection syndrome occurred in <0.1% of injections and approximately 2% of patients.

Further Information from Clinical Studies

Incidence In Clinical Studies

In clinical trials through October 14, 2008, a total of 30 post-injection syndrome events were reported in 29 patients. Based on approximately 45,000 injections of olanzapine LAI given to 2054 patients in clinical trials as of that date, post-injection syndrome events had occurred in approximately 0.07% of injections, or 1.4% of patients.1 This is consistent with a reported rate of Hoigne’s syndrome following accidental intravascular injection of IM procaine penicillin G (0.08% of injections).2 

Based on an analysis from a locked database conducted earlier in April 2008, which included 29 post-injection syndrome events, the mean exposure to olanzapine LAI therapy was 14 months (range, 2 weeks to 3.8 years) or 20 injections per patient (range, 1-100 injections), for a total of 2353.5 PY of exposure. This yielded a post-injection syndrome incidence rate of 1.2 events per 100 PY.1

Description of Data Set

An analysis of post-injection syndrome cases from 8 Lilly premarketing clinical trials (August 2000 through October 2008) in patients aged 18 to 75 years with schizophrenia or schizoaffective disorder receiving olanzapine LAI (mean exposure, 14 months; range, 2 weeks to 3.8 years) therapy was conducted.1 

Depending on the specific study, olanzapine LAI doses ranged from 45 to 405 mg, and injection intervals could be of 2, 3, or 4 weeks. Injections given at 2-week intervals could not exceed a dose of 300 mg.1

Events occurred at various olanzapine LAI doses, cumulative exposure lengths, and injection numbers.1

Further Information from Postmarketing Observational Study

A multinational, non-interventional, prospective, real-world, observational PASS was conducted to estimate the incidence per injection and per patient of post-injection syndrome events in patients with schizophrenia receiving olanzapine LAI. Patients (mean age = 41 years) included in the study had an average duration of 554 days of continuous exposure to olanzapine LAI and received an average of 26 olanzapine LAI injections per period of continuous exposure.3

A total of 103,505 olanzapine LAI injections were administered to 3858 patients enrolled in the study between April 2009 and December 2015. Post-injection syndrome occurred in

  • 0.044% of injections (n=46), and

  • 1.17% of patients (n=45).3

Based on the per injection rate of 0.044% and accounting for the possible outcome of multiple events per patient, an estimation was generated of the cumulative probabilities of at least one post-injection syndrome event for a patient over time. The results indicate that it takes 20 injections before the estimated probability of at least one post-injection syndrome event surpasses 1%.3

If a patient were to continuously use olanzapine LAI for 5 years, with a 2 or 4 week injection schedule, the estimated cumulative probability of at least one post-injection syndrome event is 3.9% and 2.5%, respectively. These results highlight that the estimated risk at each injection is the same and very rare, and that although the estimated cumulative probability of experiencing at least one event at any injection over time increases, it still remains low.3


1. Detke HC, McDonnell DP, Brunner E, et al. Post-injection delirium/sedation syndrome in patients with schizophrenia treated with olanzapine long acting injection, I: analysis of cases. BMC Psychiatry. 2010;10(1):43. http://dx.doi.org/10.1186/1471-244X-10-43

2. Downham TF, Cawley RA, Salley SO, Dal Santo G. Systemic toxic reactions to procaine penicillin G. Sex Transm Dis. 1978;5(1):4-9. http://dx.doi.org/10.1097/00007435-197801000-00002

3. Meyers KJ, Upadhyaya HP, Landry JL, et al. Postinjection delirium/sedation syndrome in patients with schizophrenia receiving olanzapine long-acting injection: results from a large observational study. BJPsych Open. 2017;3(4):186-192. http://dx.doi.org/10.1192/bjpo.bp.116.004382


LAI = Long Acting Injection = olanzapine pamoate

PASS = post-authorisation safety study

PY = patient years

Date of Last Review: December 12, 2019

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