Olanzapine Versus Quetiapine: Corrected QT Changes in Critically Ill Patients

Olanzapine and quetiapine are frequently administered atypical antipsychotic medications and their effects on the corrected QT (QTc) in the critically ill population remain understudied.

The objective of this study was to compare the impact of olanzapine and quetiapine on QTc changes in critically ill patients.

This was a single-center, retrospective analysis. Adult patients admitted to the intensive care unit (ICU) from January 2023 through July 2023 were included if they received ≥2 doses of either olanzapine or quetiapine within a 48-hour period and had one QTc evaluated within 48 hours of antipsychotic initiation. The major endpoint was a composite of the incidence of QTc prolongation (defined as QTc > 500 ms or QTc > 60 ms above baseline) following antipsychotic initiation. Univariable and multivariable analyses were performed to identify risk factors for QTc prolongation.

There was no statistical difference in the major composite endpoint between patients in the olanzapine and quetiapine groups (8/83 [9.6%] vs 19/129 [14.7%]; P = .28). The incidence of QTc > 500 ms (7/244 [2.9%] vs 20/427 [4.7%]; P = .25) and change from baseline >60 ms (5/244 [2.0%] vs 17/427 [4.0%]; P = .26) were not statistically different between the olanzapine and quetiapine groups, respectively. There were no occurrences of Torsades de Pointes or extrapyramidal symptoms in either group.

The results of this study suggest olanzapine and quetiapine may have similar impact on QTc prolongation in critically ill patients. These findings could contribute to safer prescribing practices in the ICU.