Cocaine Toxicity — MRCPsych Paper B MCQ

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ModerateSubstance MisuseCocaine ToxicityMRCPsych Paper B

A 30-year-old man is brought to the emergency department after a cocaine binge. He is severely agitated and paranoid, with a pulse of 132 beats/min, blood pressure of 186/108 mmHg, dilated pupils and a core temperature of 39.4°C. There is no clonus, hyperreflexia, muscle rigidity or reduction in respiratory rate, and no co-ingestant is reported. Which additional acute condition should be actively investigated?

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Correct answer: C — Acute rhabdomyolysis

The correct answer is **B, acute rhabdomyolysis**. Cocaine produces sympathomimetic toxicity, and marked hyperthermia combined with sustained psychomotor agitation can cause skeletal-muscle breakdown. Creatine kinase, potassium, renal function, urinalysis and urine output should be assessed because rhabdomyolysis may cause hyperkalaemia and acute kidney injury. Hyperthermia also requires immediate cooling and control of agitation, usually with benzodiazepines. Serotonin toxicity is less likely without serotonergic co-exposure, clonus or hyperreflexia. Opioid toxicity would typically cause respiratory depression, miosis and reduced consciousness. Wernicke encephalopathy requires a relevant nutritional risk and compatible neurological findings. Alcohol withdrawal requires recent cessation or reduction after dependent use and is not explained by the stated cocaine binge.

Reference: Kumar S et al. Cocaine and Alcohol Co-Ingestion-Induced Severe Rhabdomyolysis With Acute Kidney Injury: A Case Report and Literature Review (rhabdomyolysis as the principal mechanism of cocaine-associated AKI), Cureus, 2020. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7362596/