The U.S. Food and Drug Administration (FDA) is investigating two unexplained deaths in patients who received an intramuscular injection of the antipsychotic drug Zyprexa Relprevv (olanzapine pamoate). The patients died 3-4 days after receiving an appropriate dose of the drug, well after the 3-hour post-injection monitoring period required under the Zyprexa Relprevv Risk Evaluation and Mitigation Strategy (REMS).
The agency reported that both patients were found to have very high olanzapine blood levels after death.
The Zyprexa Relprevv label contains warnings about the risk of post-injection delirium sedation syndrome (PDSS), a serious condition in which the drug enters the blood too fast following an intramuscular injection, causing greatly elevated blood levels with marked sedation (possibly including coma) and/or delirium. In the clinical trials supporting the approval of Zyprexa Relprevv, cases of PDSS were observed within 3 hours after administration of Zyprexa Relprevv, but there were no deaths due to PDSS. The agency said that it is not clear whether these patients died from PDSS.
At present, the FDA is continuing its investigation and has promised updates when additional information is available.