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Theophylline monitoring — GPhC CRA MCQ

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HardRespiratory TherapeuticsTheophylline monitoringGPhC CRA

A patient taking twice-daily modified-release theophylline stopped smoking three days ago and has started an interacting antibiotic for pneumonia. They now report nausea and tremor. Which monitoring plan is most appropriate?

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Correct answer: B — Assess toxicity and obtain a theophylline level, generally 4–6 hours after the modified-release dose

Stopping smoking removes tobacco-smoke enzyme induction and can raise theophylline exposure; acute illness and interacting medicines may add further risk. Nausea and tremor are compatible with toxicity. SPS advises a one-off plasma level with toxicity, interacting treatment or changed smoking status, and for modified-release preparations the sample is generally taken 4–6 hours after a dose.

Reference: NHS SPS: Theophylline monitoring: https://www.sps.nhs.uk/monitorings/theophylline-monitoring/