Cathinones Classification — MRCPsych Paper B MCQ
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Correct answer: D — Monoamine transporter substrates or inhibitors
Explanation lettering: D = shown as B · B = shown as D
B is correct. Synthetic cathinones are psychostimulants acting principally at dopamine, noradrenaline and serotonin transporters. Their precise mechanisms vary: mephedrone predominantly acts as a transporter substrate that promotes monoamine release, whereas pyrrolidino-cathinones such as MDPV are potent monoamine-reuptake inhibitors. Both mechanisms increase extracellular monoamine concentrations and produce sympathomimetic stimulant effects. Hallucinations can occur during toxicity, but this does not make cathinones primarily 5-HT2A hallucinogens. They are not mu-opioid agonists, GABA-A positive allosteric modulators such as benzodiazepines, or CB1 agonists such as cannabinoids. Option B therefore encompasses the class without implying that every cathinone has an identical transporter action.
Reference: Advisory Council on the Misuse of Drugs. Synthetic cathinones: an updated harms assessment, section 6.1, updated 2025. https://www.gov.uk/government/publications/synthetic-cathinones-an-updated-harms-assessment/synthetic-cathinones-an-updated-harms-assessment-accessible