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AChEI GI Side Effects — MRCPsych Paper B MCQ

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ModerateOld Age PsychiatryAChEI GI Side EffectsMRCPsych Paper B

A 78-year-old woman with mild Alzheimer's disease has taken oral rivastigmine 3 mg twice daily without difficulty for 4 weeks. Five days after the dose was increased to 4.5 mg twice daily, she develops nausea and occasional vomiting. She remains able to drink, with no dehydration, abdominal pain or other concerning clinical features. What is the most appropriate management?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: C — Briefly omit doses, then resume 3 mg twice daily with meals and re-titrate cautiously; consider a patch if intolerance recurs.

Explanation lettering: C = shown as A · A = shown as B · B = shown as C · E = shown as D · D = shown as E

B is correct. The close temporal relationship to dose escalation, together with previous tolerance of 3 mg twice daily and the absence of dehydration or other red flags, indicates a dose-related cholinergic adverse effect. The UK SmPC advises omitting one or more doses if adverse reactions such as nausea or vomiting occur and, when symptoms persist, temporarily returning to the previous well-tolerated dose. Rivastigmine should be taken with morning and evening meals, and re-titration should be cautious, no sooner than the minimum two-week interval. A transdermal patch can be considered if clinically significant oral intolerance recurs. Permanent discontinuation (A) is unnecessary for a manageable adverse effect. Continuing the higher dose unchanged (C) ignores its dose-related mechanism, and long-term metoclopramide (D) masks symptoms while adding extrapyramidal and other risks in an older adult. Memantine monotherapy (E) is not indicated by NICE NG97 for mild Alzheimer's disease, particularly when the AChE inhibitor was previously tolerated.

Reference: eMC, Rivastigmine KRKA 3 mg hard capsules SmPC, sections 4.2/4.4 (dose omission, reduction to previous well-tolerated dose, dosing with meals), https://www.medicines.org.uk/emc/product/15415/smpc; NICE NG97 Dementia recommendations, https://www.nice.org.uk/guidance/ng97/chapter/recommendations