RT with Prolonged QTc — MRCPsych Paper B MCQ

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ModerateSchizophrenia & PsychosisRT with Prolonged QTcMRCPsych Paper B

A 35-year-old man with schizophrenia has a prolonged QT interval documented on his baseline ECG. He becomes severely agitated and poses an immediate risk to others. De-escalation has been unsuccessful, and oral medication is not possible, so rapid tranquillisation is required. According to NICE NG10, which intramuscular medication should be used?

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Correct answer: C — IM lorazepam

The correct answer is C, IM lorazepam. NICE NG10 recommends either IM lorazepam alone or IM haloperidol combined with IM promethazine for rapid tranquillisation in adults. However, where cardiovascular disease is present, including a prolonged QT interval, NICE specifically advises avoiding the haloperidol–promethazine combination and using IM lorazepam instead. Therefore, option E is contraindicated in this scenario. IM olanzapine and IM aripiprazole may appear plausible as injectable antipsychotics, but they are not the recommended NG10 regimen for this decision. IM chlorpromazine is also not recommended by NG10 for adult rapid tranquillisation. The documented prolonged QT interval is the decisive discriminating feature.

Reference: National Institute for Health and Care Excellence. Violence and aggression: short-term management in mental health, health and community settings (NG10), recommendations 1.4.37–1.4.39. 2015. https://www.nice.org.uk/guidance/ng10/chapter/recommendations