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Rivastigmine in PDD — MRCPsych Paper B MCQ

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ModerateOld Age PsychiatryRivastigmine in PDDMRCPsych Paper B

A 72-year-old man with Parkinson's disease dementia was using a rivastigmine 9.5 mg/24 h transdermal patch. The patch was withheld when he developed persistent nausea and diarrhoea. His symptoms have now resolved, but treatment has been interrupted for four days. What is the most appropriate next action?

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Correct answer: E — Restart rivastigmine patch 4.6 mg/24 h

The correct answer is E. Nausea and diarrhoea are dose-related cholinergic adverse effects of rivastigmine. The patch should be withheld until gastrointestinal symptoms resolve. If treatment has been interrupted for more than three days, the SmPC specifies that it should be re-initiated at 4.6 mg/24 h; if tolerated, it may later be increased to 9.5 mg/24 h after at least four weeks. Permanent discontinuation is unnecessary after reversible intolerance unless adverse effects recur or benefit no longer outweighs harm. An immediate switch to donepezil is not required before attempting safe re-titration. Restarting 9.5 mg/24 h risks renewed toxicity, and regular domperidone would mask rather than correct the dose-related adverse effect. Increasing to 13.3 mg/24 h would further increase adverse-effect risk.

Reference: Electronic Medicines Compendium, Rivastigmine Luye 9.5 mg/24 h transdermal patch, SmPC sections 4.2 and 4.4, updated 17 March 2025. https://www.medicines.org.uk/emc/product/100254/smpc