"Substance Use Disorders" — Practice

Question 1

Which triad identifies opioid overdose?

Accepted Answer

B

Question 2

In a malnourished patient with alcohol dependence brought unconscious, the correct sequence is

Accepted Answer

B

Question 3

A man admitted after a fall becomes tremulous at 10 hours, seizes at 30 hours, and by day three is disoriented, sweating and seeing insects on the walls. Explain the sequence.

Accepted Answer

This is the standard timeline of alcohol withdrawal, and each stage is predictable from the last drink.

Tremor, sweating and anxiety at 6 to 12 hours reflect loss of alcohol's positive modulation at GABA-A receptors, leaving an unopposed excitatory state. Withdrawal seizures characteristically occur at 24 to 48 hours. Delirium tremens follows at 48 to 72 hours or later, with clouded consciousness, disorientation, marked autonomic overactivity and vivid visual hallucinations, classically of small animals.

The distinction from alcoholic hallucinosis matters: that occurs earlier, at 12 to 24 hours, and crucially in clear consciousness with preserved orientation.

Management is benzodiazepines titrated to symptom severity, fluids and electrolytes, and parenteral thiamine. Delirium tremens carries significant mortality even with treatment.

Question 4

A 24-year-old is brought agitated and paranoid, convinced insects are crawling under his skin. Pupils are dilated, he is tachycardic, hypertensive and febrile. Approach?

Accepted Answer

This suggests stimulant intoxication, with amphetamine or cocaine the likely agents.

Several features separate it from a primary psychotic illness. The sympathomimetic signs of mydriasis, tachycardia, hypertension and hyperthermia are not features of schizophrenia. Tactile hallucinations, particularly formication, are characteristic of stimulant use. And the onset is acute rather than developing over weeks.

Assessment includes urine toxicology, temperature and cardiovascular monitoring, creatine kinase for rhabdomyolysis, and an electrocardiogram, while considering hyponatraemia and intracranial haemorrhage.

Management is supportive with benzodiazepines first-line for agitation, active cooling for hyperthermia and fluids. Antipsychotics are used cautiously since they lower the seizure threshold and impair thermoregulation. Resolution over hours to days confirms the diagnosis.

Question 5

A patient with alcohol dependence says he knows he drinks too much but has no intention of stopping. The doctor gives him a leaflet about liver damage and advises him to stop. Comment.

Accepted Answer

The intervention is mismatched to the stage.

He is in contemplation, aware of the problem but ambivalent about change, and information about harm is unlikely to add anything he does not already know. Direct advice to stop typically produces the patient defending his drinking, which strengthens rather than weakens his commitment to it.

Motivational interviewing works differently. It explores ambivalence rather than resolving it for the patient, elicits from him the reasons for change rather than supplying them, avoids argument, and lets him articulate the discrepancy between his drinking and his own goals.

The stages of change model matters because it matches intervention to readiness, and because it normalises relapse as part of a chronic relapsing condition rather than as evidence of failure, which affects whether he returns.

Question 6

A patient dependent on heroin completes a 10-day inpatient detoxification and is discharged abstinent. Two weeks later he dies of an overdose after using his usual amount. Explain.

Accepted Answer

Loss of tolerance is what killed him.

Chronic opioid use produces marked tolerance to respiratory depression, so a habitual user can survive doses that would be fatal to a naive person. Abstinence reverses that tolerance within days to weeks, but it does not change the dose the person remembers as normal. On relapse, the familiar amount is now an overdose.

This is why the period immediately after detoxification, after prison release and after hospital discharge carries the highest overdose mortality in this population, and why detoxification alone is not merely ineffective but actively raises risk.

The evidence-based alternative is opioid substitution therapy with methadone or buprenorphine, which reduces illicit use, blood-borne virus transmission and, most importantly, mortality. Take-home naloxone with training for the patient and family is a further specific intervention that addresses exactly this scenario.

Question 7

A 58-year-old has taken lorazepam nightly for four years, escalating the dose, and now wants to stop. Outline the risks and the approach.

Accepted Answer

Abrupt cessation is unsafe. Benzodiazepine withdrawal mirrors alcohol withdrawal because the mechanism is the same: chronic positive modulation at GABA-A receptors produces downregulation of inhibitory signalling, and sudden removal leaves an unopposed excitatory state with anxiety, insomnia, tremor, perceptual disturbance and, at the severe end, seizures.

His escalation is characteristic and worth explaining to him. Tolerance to the anxiolytic effect develops well before tolerance to sedation, so increasing the dose chases an effect that will not return while dependence deepens.

The approach is conversion to a long-acting agent such as diazepam, which produces smoother plasma levels, followed by a slow taper over months rather than weeks, with the rate adjusted to symptoms rather than to a fixed schedule. Rebound anxiety and insomnia during the taper must be predicted explicitly, because patients otherwise interpret them as the return of the original illness.

Psychological treatment for the underlying insomnia or anxiety runs alongside, since removing the drug without addressing what it was prescribed for invites relapse.

Question 8

A patient with alcohol dependence is admitted with sodium of 112 mmol/L. It is corrected rapidly overnight. Two days later he develops quadriparesis and dysarthria with preserved consciousness. Explain.

Accepted Answer

This is central pontine myelinolysis, more accurately osmotic demyelination syndrome, caused by correcting hyponatraemia too rapidly rather than by alcohol itself.

In chronic hyponatraemia, brain cells adapt by extruding intracellular osmolytes to avoid swelling. Raising serum sodium quickly reverses the osmotic gradient faster than those osmolytes can be regenerated, so water leaves the cells and demyelination follows, characteristically in the central pons where the anatomy is particularly susceptible.

The clinical picture is delayed by one to several days after the correction, which is why the link is often missed, and it produces quadriparesis, dysarthria, dysphagia and in severe cases a locked-in state, characteristically with preserved consciousness.

Patients with alcohol dependence are at particularly high risk because malnutrition, hypokalaemia and liver disease all compound susceptibility. The prevention is a strict limit on the rate of correction, generally no more than 8 to 10 mmol/L in 24 hours, with even greater caution in this population.

Question 9

A hospital proposes refusing opioid substitution therapy to patients who continue to use illicit drugs, on the grounds that treatment should require abstinence. Critique this.

Accepted Answer

The policy would harm the patients it is aimed at and would worsen population outcomes.

Dependence is a chronic relapsing condition, so continued use during treatment is an expected part of the course rather than evidence of failure or of insincerity. Requiring abstinence as a precondition excludes precisely the people at highest risk of death, transmission and criminal justice involvement, which inverts the usual principle of directing care toward greatest need.

The evidence for substitution therapy does not rest on abstinence. Methadone and buprenorphine reduce illicit use, criminal activity, blood-borne virus transmission and, most importantly, mortality, and much of that benefit accrues in patients who are not fully abstinent. Retention in treatment is itself the strongest predictor of survival, so any policy that discharges people for using increases deaths.

Harm reduction more broadly, including needle and syringe programmes and take-home naloxone, works on the same logic: reducing harm in someone still using is a legitimate and measurable goal. Abstinence remains a worthwhile aim but functions as an outcome rather than as an entry requirement.

Practice — "Substance Use Disorders"

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