A patient on phenelzine eats aged cheese and develops a severe headache with BP 220/120 mmHg. Which mechanism explains this?

Unmetabolised tyramine releases stored noradrenaline

Cheese contains an opioid that raises sympathetic tone

Phenelzine blocks beta-1 receptors and raises renin

Phenelzine blocks serotonin reuptake and causes vasodilation

A woman on long-term haloperidol has involuntary lip smacking and tongue protrusion. Which statement describes the mechanism and a recognised treatment?

D2 receptor supersensitivity; VMAT2 inhibitors such as valbenazine

Serotonin excess from SSRI use; cyproheptadine

Dopamine depletion in the striatum; levodopa

Acute D2 hypoactivity; anticholinergics such as benztropine or procyclidine

Zolpidem produces sleep with little muscle relaxation or anticonvulsant effect. Which feature of its mechanism explains this?

Selective binding to the alpha-1 subunit of GABA-A receptors

Inhibition of central histamine H1 receptors

Agonism at melatonin MT1 and MT2 receptors

Blockade of orexin receptors in the hypothalamus

A man on lithium has marked polyuria and polydipsia, and his urine remains dilute after desmopressin. What is the most likely mechanism?

Loss of collecting duct response to ADH

Osmotic diuresis from raised blood glucose

Reduced aldosterone secretion from the adrenal gland

Excess ADH secretion from the posterior pituitary

CNS and analgesic pharmacology

30 Gulf Prometric Pharmacist (DHA, DOH, MOH, SCFHS, QCHP) practice questions on CNS and analgesic pharmacology, part of Pharmacology and Medicinal Chemistry. The first 25 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Medium
A patient on phenelzine eats aged cheese and develops a severe headache with BP 220/120 mmHg. Which mechanism explains this?
1. ACheese contains an opioid that raises sympathetic tone
2. BPhenelzine blocks beta-1 receptors and raises renin
3. CPhenelzine blocks serotonin reuptake and causes vasodilation
4. DUnmetabolised tyramine releases stored noradrenaline
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Answer: D · Unmetabolised tyramine releases stored noradrenaline
MAO in the gut wall and liver normally destroys dietary tyramine. When MAO is inhibited, tyramine enters the circulation and displaces stored noradrenaline from nerve endings, causing a hypertensive crisis. Foods to avoid include aged cheese, cured meats, fermented soy and tap beer. Phentolamine can be used for the acute episode.
- A: Cheese contains tyramine rather than an opioid.
- B: Phenelzine is not a beta-blocker.
- C: Reuptake blockade of serotonin does not explain the pressor response.
Remember this
MAO inhibitors plus tyramine-rich foods can cause hypertensive crisis.
Question 2 · Medium
A patient on haloperidol has fever, lead-pipe rigidity and CK 8,000 U/L. In addition to stopping the antipsychotic and cooling, which drug may be used to reduce severe rigidity?
1. AParacetamol
2. BBenztropine
3. CPropranolol
4. DDantrolene
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Answer: D · Dantrolene
This is neuroleptic malignant syndrome, caused by sudden dopamine blockade, with heat produced by sustained muscle contraction. Dantrolene reduces calcium release from the sarcoplasmic reticulum and eases rigidity, and bromocriptine can restore dopaminergic tone. Anticholinergics worsen hyperthermia.
- A: Paracetamol is ineffective because the fever is from muscle activity.
- B: Benztropine reduces sweating and can worsen heat retention.
- C: Propranolol does not treat rigidity or hyperthermia.
Remember this
NMS needs supportive care plus dantrolene or bromocriptine; antipyretics do not work because the heat is not hypothalamic.
Question 3 · Hard
A woman on long-term haloperidol has involuntary lip smacking and tongue protrusion. Which statement describes the mechanism and a recognised treatment?
1. ASerotonin excess from SSRI use; cyproheptadine
2. BDopamine depletion in the striatum; levodopa
3. CAcute D2 hypoactivity; anticholinergics such as benztropine or procyclidine
4. DD2 receptor supersensitivity; VMAT2 inhibitors such as valbenazine
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Answer: D · D2 receptor supersensitivity; VMAT2 inhibitors such as valbenazine
This is tardive dyskinesia, which is thought to arise from upregulation and supersensitivity of D2 receptors after chronic blockade. Anticholinergics can worsen it. Valbenazine and deutetrabenazine, which inhibit vesicular monoamine transporter 2, reduce abnormal movements, and the antipsychotic dose is lowered or changed if possible.
- A: Cyproheptadine is used for serotonin syndrome.
- B: Levodopa would add dopamine to a supersensitive system and can aggravate movements.
- C: Anticholinergics treat acute dystonia and may worsen tardive dyskinesia.
Remember this
Tardive dyskinesia is treated with VMAT2 inhibitors; anticholinergics make it worse.
Question 4 · Medium
Zolpidem produces sleep with little muscle relaxation or anticonvulsant effect. Which feature of its mechanism explains this?
1. AInhibition of central histamine H1 receptors
2. BAgonism at melatonin MT1 and MT2 receptors
3. CSelective binding to the alpha-1 subunit of GABA-A receptors
4. DBlockade of orexin receptors in the hypothalamus
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Answer: C · Selective binding to the alpha-1 subunit of GABA-A receptors
Zolpidem is a non-benzodiazepine that binds preferentially to the alpha-1 subunit of the GABA-A receptor, which mainly mediates sedation, whereas alpha-2 and alpha-3 mediate anxiolysis and muscle relaxation. Complex sleep behaviours such as sleepwalking are a recognised risk, so the lowest dose is used briefly.
- A: H1 inhibition is the mechanism of doxylamine.
- B: Melatonin receptor agonism is the mechanism of ramelteon.
- D: Orexin blockade is the mechanism of suvorexant.
Remember this
Z-drugs act on the alpha-1 GABA-A subunit; warn about complex sleep behaviours.
Question 5 · Medium
A man on lithium has marked polyuria and polydipsia, and his urine remains dilute after desmopressin. What is the most likely mechanism?
1. ALoss of collecting duct response to ADH
2. BOsmotic diuresis from raised blood glucose
3. CReduced aldosterone secretion from the adrenal gland
4. DExcess ADH secretion from the posterior pituitary
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Answer: A · Loss of collecting duct response to ADH
Lithium enters collecting duct cells through sodium channels and impairs the cyclic AMP pathway and aquaporin-2 expression, so the kidney cannot concentrate urine. This is nephrogenic diabetes insipidus, and desmopressin does not correct it. Amiloride can reduce lithium uptake into the cells.
- B: No glycosuria is described in the case.
- C: Lithium does not primarily reduce aldosterone.
- D: Excess ADH would concentrate urine and cause hyponatraemia.
Remember this
Lithium can cause nephrogenic diabetes insipidus, not responsive to desmopressin.
Question 6 · Medium
A trauma patient in shock with wheeze needs induction of anaesthesia. Which feature of ketamine makes it a suitable choice?
1. ANMDA blockade with preserved blood pressure and bronchodilation
2. BMu agonism with histamine release and bradycardia
3. CGABA-A potentiation with marked vasodilation and hypotension
4. DAlpha-2 agonism with sedation and bradycardia
Answer and explanation in LearnFree account
Question 7 · Medium
Tramadol has analgesic effects through two mechanisms. Which is the correct pairing, and which patient group should avoid it?
1. AMu agonism plus serotonin-noradrenaline reuptake block; patients with epilepsy
2. BMu antagonism plus dopamine release; patients with asthma
3. CKappa agonism plus GABA potentiation; patients with hypertension
4. DNMDA blockade plus COX inhibition; patients with gastric ulcers
Answer and explanation in LearnFree account
Question 8 · Medium
A patient has a family history of malignant hyperthermia. Which pair of agents should be avoided?
1. APropofol with vecuronium infusion
2. BSevoflurane and succinylcholine
3. CKetamine with midazolam premedication
4. DFentanyl and dexmedetomidine
Answer and explanation in LearnFree account
Question 9 · Medium
Which monitoring is essential for a patient who takes clozapine for treatment-resistant schizophrenia?
1. AWeekly serum calcium measurement
2. BAnnual bone density scanning
3. CMonthly chest X-ray imaging
4. DAbsolute neutrophil count
Answer and explanation in LearnFree account
Question 10 · Easy
Naloxone reverses opioid overdose because it is a:
1. APartial agonist at the mu receptor
2. BCholinesterase inhibitor
3. CCompetitive opioid antagonist
4. DBenzodiazepine receptor antagonist
Answer and explanation in LearnFree account
Question 11 · Medium
A patient with stage 4 chronic kidney disease needs an opioid. Why should pethidine (meperidine) be avoided?
1. AIt is converted to morphine-6-glucuronide
2. BIt causes severe constipation not seen with other opioids
3. CNormeperidine accumulates and can cause seizures
4. DIt has no analgesic effect at renal doses
Answer and explanation in LearnFree account
Question 12 · Medium
A 34-year-old woman with generalised anxiety and a past benzodiazepine dependence needs a non-sedating anxiolytic. Which mechanism describes buspirone?
1. AAntagonism of histamine H1 receptors
2. BPartial agonism at 5-HT1A receptors
3. CBlockade of the serotonin transporter only
4. DPositive modulation of the GABA-A receptor
Answer and explanation in LearnFree account
Question 13 · Easy
Flumazenil is used to reverse the effect of which drug group?
1. AOpioids
2. BBenzodiazepines
3. CTricyclic antidepressants
4. DBarbiturates
Answer and explanation in LearnFree account
Question 14 · Medium
Which statement correctly compares barbiturates with benzodiazepines at the GABA-A receptor?
1. AProlong channel opening and, at high doses, open it without GABA
2. BBarbiturates have a wider safety margin than benzodiazepines
3. CBarbiturates act only by increasing the frequency of channel opening
4. DBarbiturates block the receptor like flumazenil
Answer and explanation in LearnFree account
Question 15 · Hard
A 60 kg patient needs infiltration with plain (without adrenaline) 2% lidocaine. Taking a maximum dose of 4.5 mg/kg, what is the maximum volume that can be given?
1. A27.0 mL
2. B21.0 mL
3. C13.5 mL
4. D9.0 mL
Answer and explanation in LearnFree account
Question 16 · Medium
A smoker with a history of bulimia wants help to quit. Why is bupropion unsuitable for him?
1. AIt blocks the nicotinic receptor irreversibly
2. BIt causes marked sedation and respiratory depression
3. CIt lowers the seizure threshold, which bulimia makes more likely
4. DIt increases serotonin and can cause serotonin syndrome alone
Answer and explanation in LearnFree account
Question 17 · Medium
An ECG on a patient found drowsy after taking a large number of his father's amitriptyline tablets shows sinus tachycardia and a QRS of 140 ms, and his blood pressure is 80/50 mmHg. Which immediate treatment is indicated?
1. AIntravenous physostigmine bolus
2. BIntravenous flumazenil bolus
3. CIntravenous naloxone infusion
4. DIntravenous sodium bicarbonate
Answer and explanation in LearnFree account
Question 18 · Medium
A 78-year-old woman started sertraline two weeks ago and is now confused with serum sodium 124 mmol/L. Which mechanism best explains the finding?
1. AAldosterone antagonism
2. BDirect sodium wasting by the proximal tubule
3. CSyndrome of inappropriate ADH secretion
4. DNephrogenic diabetes insipidus
Answer and explanation in LearnFree account
Question 19 · Hard
A 75 kg patient is ordered propofol 2 mg/kg for induction. The vial contains 1% propofol. What volume should be drawn up?
1. A1.5 mL
2. B22.5 mL
3. C7.5 mL
4. D15 mL
Answer and explanation in LearnFree account
Question 20 · Hard
A patient with an eGFR of 12 mL/min needs strong opioid analgesia. Which choice is best and why?
1. AFentanyl, as it is metabolised to inactive metabolites
2. BMorphine, because its metabolites are cleared by dialysis only
3. CPethidine, because normeperidine is excreted by the liver
4. DCodeine, because it has no active metabolites
Answer and explanation in LearnFree account
Question 21 · Medium
A 25-year-old man starts olanzapine and gains 8 kg in two months with a raised fasting glucose. Which receptor blockade is thought to drive the appetite and weight gain?
1. ADopamine D2 in the nigrostriatal pathway
2. BHistamine H1 and serotonin 5-HT2C
3. CAlpha-2 adrenergic receptors
4. DNicotinic acetylcholine receptors
Answer and explanation in LearnFree account
Question 22 · Easy
The analgesic effect of morphine is produced mainly by agonism at which receptor?
1. ACannabinoid CB1 receptor
2. BMu opioid receptor
3. CGABA-B receptor
4. DKappa opioid receptor only
Answer and explanation in LearnFree account
Question 23 · Medium
A patient on long-term morphine for cancer pain develops constipation but no longer has drowsiness or nausea. Which opioid effect shows the least tolerance with prolonged use?
1. ARespiratory depression
2. BConstipation
3. CEuphoria
4. DAnalgesia
Answer and explanation in LearnFree account
Question 24 · Hard
A man treated at a Muscat hospital for methadone overdose receives naloxone 0.4 mg IV and wakes up. One hour later he is drowsy again with a respiratory rate of 6/min. What is the best explanation and action?
1. AThe first dose induced withdrawal, which now causes sedation
2. BNaloxone has become ineffective because the patient is now tolerant to it
3. CMethadone is an NMDA antagonist and cannot be reversed at mu receptors
4. DMethadone outlasts naloxone, so repeat naloxone or infuse it and observe closely
Answer and explanation in LearnFree account
Question 25 · Medium
A patient has a seizure and ventricular arrhythmia shortly after a large dose of bupivacaine was injected for a nerve block. Which treatment is specific for this toxicity?
1. AIntravenous 20% lipid emulsion
2. BIntravenous flumazenil infusion
3. CIntravenous atropine 3 mg alone
4. DIntravenous naloxone bolus
Answer and explanation in LearnFree account

5 more CNS and analgesic pharmacology questions

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CNS and analgesic pharmacology

A patient on phenelzine eats aged cheese and develops a severe headache with BP 220/120 mmHg. Which mechanism explains this?

A patient on haloperidol has fever, lead-pipe rigidity and CK 8,000 U/L. In addition to stopping the antipsychotic and cooling, which drug may be used to reduce severe rigidity?

A woman on long-term haloperidol has involuntary lip smacking and tongue protrusion. Which statement describes the mechanism and a recognised treatment?

Zolpidem produces sleep with little muscle relaxation or anticonvulsant effect. Which feature of its mechanism explains this?

A man on lithium has marked polyuria and polydipsia, and his urine remains dilute after desmopressin. What is the most likely mechanism?

A trauma patient in shock with wheeze needs induction of anaesthesia. Which feature of ketamine makes it a suitable choice?

Tramadol has analgesic effects through two mechanisms. Which is the correct pairing, and which patient group should avoid it?

A patient has a family history of malignant hyperthermia. Which pair of agents should be avoided?

Which monitoring is essential for a patient who takes clozapine for treatment-resistant schizophrenia?

Naloxone reverses opioid overdose because it is a:

A patient with stage 4 chronic kidney disease needs an opioid. Why should pethidine (meperidine) be avoided?

A 34-year-old woman with generalised anxiety and a past benzodiazepine dependence needs a non-sedating anxiolytic. Which mechanism describes buspirone?

Flumazenil is used to reverse the effect of which drug group?

Which statement correctly compares barbiturates with benzodiazepines at the GABA-A receptor?

A 60 kg patient needs infiltration with plain (without adrenaline) 2% lidocaine. Taking a maximum dose of 4.5 mg/kg, what is the maximum volume that can be given?

A smoker with a history of bulimia wants help to quit. Why is bupropion unsuitable for him?

An ECG on a patient found drowsy after taking a large number of his father's amitriptyline tablets shows sinus tachycardia and a QRS of 140 ms, and his blood pressure is 80/50 mmHg. Which immediate treatment is indicated?

A 78-year-old woman started sertraline two weeks ago and is now confused with serum sodium 124 mmol/L. Which mechanism best explains the finding?

A 75 kg patient is ordered propofol 2 mg/kg for induction. The vial contains 1% propofol. What volume should be drawn up?

A patient with an eGFR of 12 mL/min needs strong opioid analgesia. Which choice is best and why?

A 25-year-old man starts olanzapine and gains 8 kg in two months with a raised fasting glucose. Which receptor blockade is thought to drive the appetite and weight gain?

The analgesic effect of morphine is produced mainly by agonism at which receptor?

A patient on long-term morphine for cancer pain develops constipation but no longer has drowsiness or nausea. Which opioid effect shows the least tolerance with prolonged use?

A man treated at a Muscat hospital for methadone overdose receives naloxone 0.4 mg IV and wakes up. One hour later he is drowsy again with a respiratory rate of 6/min. What is the best explanation and action?

A patient has a seizure and ventricular arrhythmia shortly after a large dose of bupivacaine was injected for a nerve block. Which treatment is specific for this toxicity?