Torsade de Pointes after Administration of Droperidol for Nausea andVomiting

QT prolongation, torsades des pointes, and cardiac arrest after 4 mg of IV ondansetron

Ondansetron is a commonly used antiemetic in the emergency department despite a 2011 FDA warning regarding dose-related QTc prolongation and torsades des pointes (TdP). Cases of TdP from small ondansetron doses administered in the emergency department are lacking. A 41-year-old-woman with alcohol use disorder on no medications or supplements presented to an emergency department with one day of nausea, vomiting, and epigastric pain. Examination revealed a pulse of 77 beats/min and epigastric tenderness. The patient received 4 mg IV ondansetron, 30 mg IV ketorolac, and was placed on cardiac monitoring. ECG obtained one minute after ondansetron demonstrated premature ventricular contractions with QTc = 653 ms. Thirteen minutes after receiving ondansetron she suffered TdP and cardiac arrest. She received immediate CPR and IV epinephrine with successful defibrillation at one minute. She then received IV magnesium. Post-arrest ECGs demonstrated persistent QTc prolongation immediately and at three hours post-arrest. Laboratory studies, drawn prior to arrest, demonstrated hypokalemia (3.2 mEq/L), hypomagnesemia (1.3 mg/dL), and elevated lipase (4918 IU/L). She received no additional QT-prolonging agents. Transthoracic echocardiogram and troponins were normal; ECG intervals completely normalized within 12 h and she was discharged neurologically intact. The patient returned 18 months later with recurrent pancreatitis and similar electrolyte abnormalities; QT-prolonging drugs were avoided at that time and her course was uncomplicated. QT prolongation with subsequent torsades des pointes and cardiac arrest may occur in high-risk patients receiving small doses of ondansetron. Further studies are warranted to determine the safest antiemetic for use in the emergency department.

Ondansetron and the risk of cardiac arrhythmias: a systematic review and postmarketing analysis

STUDY OBJECTIVE

To explore the risk of cardiac arrhythmias associated with ondansetron administration in the context of recent recommendations for identification of high-risk individuals.

METHODS

We conducted a postmarketing analysis and systematically reviewed the published literature, grey literature, manufacturer's database, Food and Drug Administration Adverse Events Reporting System, and the World Health Organization Individual Safety Case Reports Database (VigiBase). Eligible cases described a documented (or perceived) arrhythmia within 24 hours of ondansetron administration. The primary outcome was arrhythmia occurrence temporally associated with the administration of a single, oral ondansetron dose. Secondary objectives included identifying all cases associating ondansetron administration (any dose, frequency, or route) to an arrhythmia.

RESULTS

Primary: No reports describing an arrhythmia associated with single oral ondansetron dose administration were identified. Secondary: Sixty unique reports were identified. Route of administration was predominantly intravenous (80%). A significant medical history (67%) or concomitant use of a QT-prolonging medication (67%) was identified in 83% of reports. Approximately one third occurred in patients receiving chemotherapeutic agents, many of which are known to prolong the QT interval. An additional third involved administration to prevent postoperative vomiting.

CONCLUSION

Current evidence does not support routine ECG and electrolyte screening before single oral ondansetron dose administration to individuals without known risk factors. Screening should be targeted to high-risk patients and those receiving ondansetron intravenously.

News Flash: Old Mother Hubbard Reports the Cupboard is Bare… Time for the FDA to Let Droperidol Out of the (Black) Box

A quick way for a clinical pharmacist to eliminate himself or herself from “employee of the month” consideration is to mention the term medication shortage. Even with training geared toward maximizing resources, the cumulative disappearance of a plethora of medications for the treatment of nausea, vomiting, and/or primary headaches is almost too much for emergency medicine physicians to manage. With prochlorperazine, metoclopramide, promethazine, and ondansetron in increasingly short supply, it is time for the Food and Drug Administration to revisit droperidol's black box warning driven by Q Tc interval prolongation, given its questionable validity, and restore droperidol's place in the armamentarium of emergency medicine physicians.