Introduction:
This set of MCQs on narcotic and non-narcotic analgesics is designed for M.Pharm students preparing for advanced pharmacology examinations. The questions probe mechanisms of action, receptor pharmacology, pharmacokinetics, clinical uses, adverse effects, and important drug interactions of opioids, NSAIDs, acetaminophen and adjuvant analgesics. Emphasis is placed on receptor subtypes, partial agonists, tolerance and dependence, COX selectivity, and drug metabolism — topics frequently tested in postgraduate courses. Use these questions to evaluate your conceptual understanding and to identify areas requiring deeper study for evidence-based prescribing and safe clinical application.
Q1. Which opioid receptor subtype is primarily responsible for supraspinal analgesia and respiratory depression?
- Delta (δ) receptor
- Kappa (κ) receptor
- Mu (μ) receptor
- Nociceptin/orphanin FQ (NOP) receptor
Correct Answer: Mu (μ) receptor
Q2. Which of the following describes the mechanism of action of nonsteroidal anti-inflammatory drugs (NSAIDs)?
- Inhibition of voltage-gated sodium channels in nociceptors
- Inhibition of cyclooxygenase enzymes reducing prostaglandin synthesis
- Agonism at mu-opioid receptors in the periaqueductal gray
- Activation of GABA-A receptors in the spinal cord
Correct Answer: Inhibition of cyclooxygenase enzymes reducing prostaglandin synthesis
Q3. Which opioid is a partial agonist at mu receptors and can precipitate withdrawal in opioid-dependent patients?
- Morphine
- Buprenorphine
- Methadone
- Fentanyl
Correct Answer: Buprenorphine
Q4. Which NSAID has preferential COX-2 inhibition and was developed to reduce GI toxicity compared with nonselective NSAIDs?
- Aspirin
- Ibuprofen
- Celecoxib
- Naproxen
Correct Answer: Celecoxib
Q5. Tramadol’s analgesic effects are mediated by which combined mechanisms?
- Pure mu-opioid agonism only
- NMDA receptor antagonism and GABA reuptake inhibition
- Weak mu-opioid agonism and inhibition of serotonin and norepinephrine reuptake
- COX inhibition and alpha-2 adrenergic agonism
Correct Answer: Weak mu-opioid agonism and inhibition of serotonin and norepinephrine reuptake
Q6. Which agent is the opioid antagonist of choice for acute opioid overdose due to its rapid onset and ability to reverse respiratory depression?
- Naloxone
- Naltrexone
- Flumazenil
- Buprenorphine
Correct Answer: Naloxone
Q7. Which of the following best explains aspirin’s cardioprotective effect at low doses?
- Inhibition of COX-2 mediated endothelial prostacyclin production
- Irreversible inhibition of platelet COX-1 limiting thromboxane A2 synthesis
- Reversible inhibition of leukocyte COX-2 reducing inflammation
- Enhanced production of nitric oxide by vascular endothelium
Correct Answer: Irreversible inhibition of platelet COX-1 limiting thromboxane A2 synthesis
Q8. Which adverse effect is most characteristic of chronic opioid therapy and often does not undergo tolerance?
- Miosis (pinpoint pupils)
- Constipation
- Respiratory depression
- Pruritus
Correct Answer: Constipation
Q9. Acetaminophen (paracetamol) analgesic action is primarily attributed to which mechanism?
- Peripheral COX-1 inhibition in inflamed tissues
- Selective COX-2 inhibition in joints
- Central inhibition of prostaglandin synthesis and modulation of serotonergic pathways
- NMDA receptor antagonism in the spinal cord
Correct Answer: Central inhibition of prostaglandin synthesis and modulation of serotonergic pathways
Q10. Which opioid has a very long half-life and NMDA receptor antagonism that makes it useful for opioid rotation and neuropathic pain?
- Morphine
- Methadone
- Hydromorphone
Correct Answer: Methadone
Q11. Which enzyme is primarily responsible for the bioactivation of codeine to morphine, accounting for variability in analgesic response?
- CYP2D6
- CYP3A4
- UGT2B7
- Monoamine oxidase (MAO)
Correct Answer: CYP2D6
Q12. NSAID-induced renal adverse effects are chiefly due to inhibition of which renal prostaglandin-mediated process?
- Glomerular filtration barrier synthesis
- Renal vasodilation of afferent arteriole maintaining renal blood flow
- Sodium reabsorption in the distal tubule
- Renin secretion increase leading to hypotension
Correct Answer: Renal vasodilation of afferent arteriole maintaining renal blood flow
Q13. Which opioid is preferred for analgesia in renal failure because it has inactive metabolites and limited renal excretion?
- Codeine
- Meperidine
- Fentanyl
- Hydromorphone
Correct Answer: Fentanyl
Q14. Which adverse reaction is most specifically associated with the NSAID class inhibition of COX-1?
- Elevation of liver enzymes
- Gastrointestinal mucosal erosion and bleeding
- Renal hypoperfusion only
- Serotonin syndrome
Correct Answer: Gastrointestinal mucosal erosion and bleeding
Q15. Which analgesic adjuvant acts as an NMDA receptor antagonist and is used to reduce opioid tolerance and neuropathic pain?
- Ketamine
- Amitriptyline
- Pregabalin
- Dexmedetomidine
Correct Answer: Ketamine
Q16. Which statement correctly describes aspirin’s antiplatelet effect compared with other NSAIDs?
- Aspirin’s antiplatelet effect is reversible and short-lived
- Aspirin irreversibly inhibits platelet COX-1, causing prolonged platelet dysfunction
- Aspirin selectively inhibits COX-2 in platelets
- Aspirin does not affect thromboxane A2 synthesis
Correct Answer: Aspirin irreversibly inhibits platelet COX-1, causing prolonged platelet dysfunction
Q17. Which opioid agonist is associated with accumulation of a neurotoxic metabolite (normeperidine) that can cause seizures, especially in renal impairment?
- Meperidine
- Oxymorphone
- Hydrocodone
- Tapentadol
Correct Answer: Meperidine
Q18. Which class of analgesics increases the risk of cardiovascular events when used chronically, particularly agents with higher COX-2 selectivity?
- Nonselective benzodiazepines
- Selective serotonin reuptake inhibitors
- Selective COX-2 inhibitors (coxibs)
- Opioid partial agonists
Correct Answer: Selective COX-2 inhibitors (coxibs)
Q19. Which pharmacologic strategy is most appropriate to manage opioid-induced constipation in a chronic opioid user?
- Decrease dietary fiber and fluid intake
- Start stimulant laxatives and consider peripherally acting mu-opioid receptor antagonists (PAMORAs)
- Increase opioid dose to overcome constipation
- Use naloxone systemically to reverse opioid effect
Correct Answer: Start stimulant laxatives and consider peripherally acting mu-opioid receptor antagonists (PAMORAs)
Q20. In a patient taking SSRIs, which analgesic has a significant interaction increasing the risk of serotonin syndrome when combined with serotonergic opioids?
- Ibuprofen
- Oxycodone
- Tramadol
- Acetaminophen
Correct Answer: Tramadol
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