WEBB FELLOW: Safety of Intravenous Olanzapine and Important Considerations when Using Intravenous Antipsychotics

Abstract:

Background: Antipsychotics have an important role in the treatment of acute agitation, but the use of intravenous (IV) antipsychotics is relatively specific to consultation-liaison (C-L) and emergency settings. There is limited literature about the safety and efficacy of IV antipsychotics, so their use is inconsistent across settings and institutions. This retrospective study reports safety outcomes with use of IV olanzapine in medical, surgical, and intensive care settings and contextualizes findings within current literature about IV antipsychotics.



Methods: Retrospective chart review of patients age 18 years or older admitted to an urban general hospital who received at least 1 dose of IV olanzapine from 2013-2022. Vital signs in the four hours following each dose were reviewed for hypotension, bradycardia, bradypnea, and oxygen desaturation. The serious adverse outcomes screened for were intubation and death. Confounding and contextual factors reviewed include concomitant medications and use of physical restraints. Findings are presented using descriptive statistics. This study was approved by the Institutional Review Board.



Results: Over 1000 total doses of IV olanzapine were identified across 298 patients. Doses ranged from 1-20mg and the most common dose was 5mg. Agitation was the most common indication. On preliminary analysis, the overall rate of doses associated at least one adverse event was 13%, with the most common adverse events being bradycardia and oxygen desaturation, with frequencies slightly higher than previous studies of IV olanzapine (Hunt 2021, Khorassani 2019). These data add to the current literature about safety of IV antipsychotics and may help clarify if there is a role for use of IV second generation antipsychotics (SGAs) for patients on medical-surgical and intensive care units.

Discussion: There are currently no antipsychotics that are FDA-approved for intravenous use. Haloperidol is generally observed to be the most commonly used IV antipsychotic due to widespread familiarity. However, SGAs are generally found to have better safety profiles compared to first generation agents, so it is worth expanding our understanding of the safety and efficacy of IV SGAs to better clarify their role in the treatment of general hospital patients. Many previous studies on IV olanzapine have taken place in emergency department settings in which the patient population may be distinct from hospital inpatients. Considering the limitations of most studies to date, further prospective and comparative studies will help clarify the role of IV SGAs.