Effect of intravenous odansetron in hospitalized patients on measured QTC interval


Advocate Lutheran General Hospital


Introduction: Ondansetron is commonly used in hospitalized patients to treat nausea and vomiting. Ondansetron is a known QT-prolonging medication, but its effect on QTc in hospitalized patients has not been fully established. Objective: Evaluation of changes in corrected QT intervals (QTc) on followup EKGs after the administration of ondansetron plus or minus the co-administration of a QT-prolonging medication.

Methods: This was a single-institution, retrospective study utilizing electronic medical records from January 2017 - December 2017. All adult patients who had an initial EKG during the hospitalization prior to receiving intravenous ondansetron and a subsequent EKG performed within six hours of the administration of ondansetron were included. Patients were then separated into Group I, (receiving a QT-prolonging medication at the time of ondansetron administration), and Group II, (not receiving an additional QT-prolonging medication at the time of ondansetron administration). Group III consisted of randomized group of age and sex-matched controls.

Results: A total of 55 inpatients met our patient inclusion criteria, (17 patients in Group I and 38 patients in Group II). Mean change in QTc were +10.3ms in Group I (p = 0.21), +2.2ms in Group II (p = 0.0001), and 3.5ms in Group III (p = 0.13). Follow up QTc >500ms was seen in 4/17 (24%) patients in Group I, 4/38 (11%) patients in Group II and 3/100 patients in Group III (3%). Compared to Group III, OR for the development of QTc >500ms in Group I was 10.8 (95% CI 2.1-54.1, p <0.01).

Conclusion: Patients receiving ondansetron with another QT-prolonging medication (Group I), are at risk of having a QTc over 500ms on their follow up EKG. Hospitalized patients that receive IV ondansetron co-administered with another QT-prolonging drug require close monitoring to avoid the development of arrhythmias.

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