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QTc Normal Value — FRCA Primary MCQ

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HardPhysiology - CardiovascularQTc Normal ValueFRCA Primary

For an adult receiving ondansetron intravenously, what is the maximum recommended single dose following the MHRA QT-prolongation warning?

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Correct answer: D — 16 mg intravenously as a single dose

The best answer is “16 mg intravenously as a single dose”. The MHRA limits a single intravenous ondansetron dose in adults to 16 mg because QTc prolongation is dose dependent. Four or eight milligrams may be used in appropriate clinical settings, but they are not the maximum single dose; 24 mg and 32 mg exceed the safety limit.

Reference: MHRA, Ondansetron for intravenous use: dose-dependent QT prolongation: https://www.gov.uk/drug-safety-update/ondansetron-for-intravenous-use-dose-dependent-qt-interval-prolongation