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Synthetic Cathinones Classification — MRCPsych Paper B MCQ

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ModerateSubstance MisuseSynthetic Cathinones ClassificationMRCPsych Paper B

A 30-year-old woman is brought to the emergency department after insufflating a powder purchased online. She is severely agitated and paranoid, with tachycardia, hypertension and dilated pupils. Laboratory analysis identifies methcathinone. Which pharmacological description best fits this substance?

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Correct answer: E — Synthetic stimulant acting through monoamine release and transporter inhibition

Methcathinone is a synthetic cathinone and central nervous system stimulant structurally related to amphetamine. It increases synaptic monoamines, particularly dopamine and noradrenaline, through transporter-mediated release together with inhibition of DAT and NET reuptake. This produces a sympathomimetic syndrome and can cause severe agitation, paranoia, delusions and psychosis. Opioids more typically cause sedation, respiratory depression and miosis. GABA-A positive modulators are sedative-hypnotics rather than stimulants. Cannabinoids may provoke paranoia but methcathinone does not act primarily at CB1 receptors. Classical serotonergic psychedelics principally act through 5-HT2A receptor agonism and are a different pharmacological class.

Reference: Advisory Council on the Misuse of Drugs. Synthetic cathinones: an updated harms assessment, sections 5–6, updated 2025. https://www.gov.uk/government/publications/synthetic-cathinones-an-updated-harms-assessment/synthetic-cathinones-an-updated-harms-assessment-accessible