Substance misuse accounts for approximately 8% of Paper B marks. The questions are highly predictable because the presentations, withdrawal syndromes, and management protocols are standardised across clinical practice. Recall documents confirm that the same patterns reappear across sittings: alcohol withdrawal management in liver failure, opioid overdose treatment, and distinguishing between substances based on their clinical presentation.
Alcohol
Alcohol Withdrawal
Alcohol withdrawal typically begins 4-12 hours after the last drink. This is a specific figure that appears in recalls. Symptoms include tremor, sweating, anxiety, agitation, nausea, tachycardia, and hypertension. Without treatment, progression to alcohol withdrawal seizures (12-48 hours) and delirium tremens (48-96 hours). Delirium tremens: confusion, visual/tactile hallucinations, autonomic hyperactivity, 5-10% mortality if untreated.
Management of alcohol withdrawal: Reducing-dose benzodiazepine regimen. Chlordiazepoxide is the most commonly used. For acute liver failure: oxazepam (does not undergo hepatic oxidation — conjugated directly). A recall confirmed this: “Alcohol withdrawal, patient in acute liver failure — what to use?” Answer: oxazepam.
Thiamine: All patients with alcohol dependence should receive parenteral thiamine (Pabrinex) to prevent Wernicke’s encephalopathy (confusion, ataxia, ophthalmoplegia with nystagmus as most common ocular sign). Korsakoff syndrome: anterograde amnesia and confabulation.
Alcohol + GABA-A/NMDA: Alcohol acts on BOTH GABA-A (agonist, enhanced inhibition) AND NMDA (antagonist, reduced excitation). Benzodiazepines affect GABA-A only. Ketamine affects NMDA only. Exam question: “Which one acts on both GABA-A and NMDA?” Answer: alcohol.
Alcohol Dependence Treatment
Psychosocial interventions first-line. Pharmacological options: acamprosate (craving via glutamate modulation), naltrexone (opioid-mediated reward), disulfiram (aversive, second-line).
Opioids
Opioid overdose: Pinpoint pupils, respiratory depression, reduced conscious level. Naloxone IM (short half-life of 20-60 minutes — monitor for re-emergence of overdose). Methadone overdose needs repeated naloxone or infusion due to its 24-36 hour half-life.
Opioid dependence: Methadone (full agonist, long half-life, once daily, supervised initially) or buprenorphine (partial agonist, lower overdose risk, ceiling effect).
Stimulants and Other Drugs
Cocaine: Short-acting full agonist at dopamine/noradrenaline/serotonin transporters. Increased energy, euphoria, decreased sleep. Medical complications: MI, seizures, aortic dissection.
Cannabis: Laughing, giggling, relaxed, amotivational syndrome with chronic use. Synthetic cannabinoids (“Spice”) = full CB1 agonists (more potent, paranoia, hallucinations).
Ketamine: NMDA antagonist. Chronic use: ketamine cystitis (bladder atrophy, bleeding, renal failure).
Most likely to form physical dependence: Alprazolam (short half-life benzodiazepine produces severe withdrawal).
High-Yield Recall Patterns
- Alcohol withdrawal + acute liver failure: Oxazepam
- Acts on both GABA-A and NMDA: Alcohol
- Pinpoint pupils + respiratory depression: Opioid overdose = naloxone IM
- Laughing, giggling, relaxed, usually smoked: Cannabis
- Increased energy, decreased sleep, short-acting: Cocaine
- Full agonist, paranoia, hallucinations: Synthetic cannabinoid
- Chronic ketamine + bladder pain + haematuria: Ketamine cystitis
- Jittery, overaroused newborn + maternal history: Opioid exposure
- Most likely to form physical dependence: Alprazolam
PsychStar’s Paper B question bank includes dedicated substance misuse questions with recall-calibrated difficulty. Start with 5 free questions at psychstar.io/try.