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Gentamicin monitoring — GPhC CRA MCQ

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HardInfectionsGentamicin monitoringGPhC CRA

Under a hospital’s 12-to-18-hour extended-interval gentamicin protocol, a patient receives the first dose at 14:00. A serum sample is taken at 05:00 the next day and renal function remains stable. How should the pharmacist interpret the timing?

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Correct answer: B — The 15-hour concentration is timed for plotting on the local nomogram

The sample was taken 15 hours after administration, within this protocol’s 12-to-18-hour post-dose window, so the measured concentration is plotted on the stated nomogram to select the next interval. The exact administration and sampling times, renal trend and protocol exclusions still need confirmation. This is extended-interval monitoring rather than conventional peak-and-trough sampling.

Reference: Gloucestershire Hospitals, Once-daily gentamicin administration and monitoring in adults, January 2026: https://www.gloshospitals.nhs.uk/documents/2118/Once_Daily_Gentamicin_Administration_and_Monitoring_in_Adults_Jan_2026.pdf