Correct (2): Ondansetron prolongs QT. With baseline QTc ≥500 ms, electrolyte abnormalities (low K/Mg), and other QT-prolonging drugs (methadone), risk of torsades de pointes is high. Hold ondansetron, correct K/Mg, notify provider; alternative antiemetic (e.g., scopolamine, granisetron with lower QT effect, or aprepitant) may be considered. (1,3,4) Normal findings.
Clinical scenario
Scenario 55-year-old female receiving chemotherapy; ondansetron 8 mg IV ordered for nausea. ECG: QTc 510 ms, K+ 3.3, also on methadone.
For study reference only. Always follow current clinical guidelines and your institution’s protocols.