This concise, exam-focused set of Opioid analgesics MCQs With Answer is designed for B. Pharm students to deepen understanding of opioid pharmacology, clinical use, and safety. Questions cover mechanism of action at mu, kappa and delta receptors, pharmacokinetics of morphine, codeine, fentanyl and methadone, metabolism (CYP2D6, glucuronidation), adverse effects such as respiratory depression, constipation and tolerance, dependence and withdrawal, and management of overdose with naloxone. Emphasis is on drug interactions, equianalgesic dosing, partial agonists and mixed agonist–antagonists, and therapeutic monitoring. Clear answers with explanations will help prepare for exams and clinical pharmacy practice. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which receptor subtype is primarily responsible for opioid-mediated analgesia and respiratory depression?
- Delta (δ) receptor
- Kappa (κ) receptor
- Mu (μ) receptor
- Nociceptin receptor
Correct Answer: Mu (μ) receptor
Q2. What is the primary intracellular mechanism by which μ-opioid receptor activation produces analgesia?
- Activation of adenylate cyclase and increased cAMP
- Gq-mediated phospholipase C activation
- Gi/Go-mediated inhibition of adenylate cyclase and decreased cAMP
- Direct opening of ligand-gated sodium channels
Correct Answer: Gi/Go-mediated inhibition of adenylate cyclase and decreased cAMP
Q3. Which opioid is a prodrug requiring CYP2D6-mediated O-demethylation to form its active analgesic metabolite?
- Fentanyl
- Tramadol
- Codeine
- Morphine
Correct Answer: Codeine
Q4. Which opioid is most associated with accumulation of an active glucuronide metabolite that may cause prolonged sedation in renal failure?
- Methadone
- Morphine
- Fentanyl
- Buprenorphine
Correct Answer: Morphine
Q5. Which opioid has the highest potency and is commonly used in anesthesia as a short-acting IV analgesic?
- Hydrocodone
- Fentanyl
- Codeine
- Morphine
Correct Answer: Fentanyl
Q6. Buprenorphine is best described pharmacologically as:
- Full μ-opioid receptor agonist
- Pure κ-opioid receptor antagonist
- Partial μ-opioid receptor agonist with high affinity
- Non-opioid NMDA antagonist
Correct Answer: Partial μ-opioid receptor agonist with high affinity
Q7. Which agent is the standard opioid antagonist used acutely to reverse opioid overdose?
- Naltrexone
- Naloxone
- Flumazenil
- Buprenorphine
Correct Answer: Naloxone
Q8. Which adverse effect of opioids does NOT typically show tolerance with chronic use?
- Miosis
- Respiratory depression
- Analgesia
- Sedation
Correct Answer: Miosis
Q9. Tramadol’s analgesic effect is due to both weak μ-opioid agonism and:
- Selective COX-2 inhibition
- Reuptake inhibition of serotonin and norepinephrine
- NMDA receptor antagonism
- GABA-B receptor activation
Correct Answer: Reuptake inhibition of serotonin and norepinephrine
Q10. Which opioid is associated with QT prolongation and requires caution due to risk of torsades de pointes?
- Methadone
- Codeine
- Morphine
Correct Answer: Methadone
Q11. Which mixed agonist–antagonist has κ-agonist and μ-antagonist properties and may precipitate withdrawal in opioid-dependent patients?
- Nalbuphine
- Benzhydrocodone
- Naltrexone
- Meperidine
Correct Answer: Nalbuphine
Q12. Which metabolite of morphine has greater potency and contributes to analgesia but may accumulate in renal impairment?
- Morphine-3-glucuronide (M3G)
- Morphine-6-glucuronide (M6G)
- Normorphine
- Codeine
Correct Answer: Morphine-6-glucuronide (M6G)
Q13. Which opioid is preferred for neuropathic pain among the listed options due to combined opioid and monoaminergic effects?
- Tapentadol
- Fentanyl
- Codeine
- Meperidine
Correct Answer: Tapentadol
Q14. Opioid-induced hyperalgesia is best characterized by:
- Reduced pain sensitivity after chronic opioid use
- Paradoxical increased pain sensitivity after prolonged opioid exposure
- Complete loss of analgesic efficacy from the first dose
- Enhanced opioid receptor expression leading to stronger analgesia
Correct Answer: Paradoxical increased pain sensitivity after prolonged opioid exposure
Q15. Which statement about naloxone is true?
- It is a long-acting oral opioid antagonist used for maintenance therapy
- It is a short-acting opioid antagonist used IV to reverse respiratory depression
- It is a partial μ-agonist used to treat chronic pain
- It increases opioid-induced miosis
Correct Answer: It is a short-acting opioid antagonist used IV to reverse respiratory depression
Q16. Which interaction increases risk of severe respiratory depression when combined with opioids?
- SSRIs
- Benzodiazepines
- NSAIDs
- Proton pump inhibitors
Correct Answer: Benzodiazepines
Q17. Equianalgesic dosing refers to:
- Different drugs producing equal side effect profiles
- Drug doses that produce approximately the same analgesic effect
- Doses that are equal by volume but different potency
- Standardized doses used only in experimental animals
Correct Answer: Drug doses that produce approximately the same analgesic effect
Q18. Which opioid is known to cause serotonergic syndrome risk when combined with SSRIs due to serotonin reuptake inhibition?
- Hydrocodone
- Tramadol
- Buprenorphine
- Fentanyl
Correct Answer: Tramadol
Q19. Which opioid is commonly used in opioid substitution therapy for maintenance because of long half-life and NMDA antagonism?
- Morphine
- Methadone
- Codeine
- Fentanyl
Correct Answer: Methadone
Q20. Which adverse effect results from opioid-induced decreased gastrointestinal motility and does not reliably show tolerance?
- Urinary retention
- Constipation
- Bradycardia
- Itching
Correct Answer: Constipation
Q21. Which opioid receptor is most associated with dysphoria and psychotomimetic effects when activated?
- Mu (μ) receptor
- Kappa (κ) receptor
- Delta (δ) receptor
- Opioid growth factor receptor
Correct Answer: Kappa (κ) receptor
Q22. Which opioid analgesic is contraindicated or used with extreme caution in older adults due to risk of neurotoxic metabolite (normeperidine)?
- Meperidine
- Hydromorphone
- Oxycodone
- Buprenorphine
Correct Answer: Meperidine
Q23. Partial agonists like buprenorphine have which clinical property compared with full agonists?
- No risk of dependence
- Ceiling effect for respiratory depression and analgesia
- Greater respiratory depression at low doses
- They are purely antagonistic at μ receptors
Correct Answer: Ceiling effect for respiratory depression and analgesia
Q24. Which hepatic enzyme system is most relevant for methadone and fentanyl metabolism and important for drug interactions?
- CYP3A4 and CYP2D6
- Monoamine oxidase
- Uridine glucuronyl transferase (UGT) only
- Carbonic anhydrase
Correct Answer: CYP3A4 and CYP2D6
Q25. Which approach is recommended to manage opioid-induced constipation in a patient on long-term opioids?
- Stop all laxatives immediately
- Use stimulant laxatives and consider peripherally acting μ-opioid receptor antagonists
- Increase opioid dose to overcome constipation
- Prescribe naloxone orally for systemic antagonism
Correct Answer: Use stimulant laxatives and consider peripherally acting μ-opioid receptor antagonists
Q26. Which statement about opioid tolerance and dependence is correct?
- Tolerance and dependence are identical and always clinically harmful
- Tolerance is reduced drug effect over time; dependence is physiologic adaptation leading to withdrawal on cessation
- Dependence prevents addiction and therefore is beneficial
- Tolerance cannot develop to analgesic effects
Correct Answer: Tolerance is reduced drug effect over time; dependence is physiologic adaptation leading to withdrawal on cessation
Q27. Which formulation provides continuous systemic delivery of fentanyl over days for chronic pain?
- Oral immediate-release tablet
- Transdermal patch
- Intramuscular depot injection
- Nasal spray
Correct Answer: Transdermal patch
Q28. Which opioid is least likely to cause histamine-mediated hypotension and itching?
- Morphine
- Meperidine
- Fentanyl
- Hydromorphone
Correct Answer: Fentanyl
Q29. For a patient on chronic high-dose opioids requiring surgery, best perioperative strategy to avoid withdrawal is:
- Stop opioids 48 hours before surgery without substitution
- Continue baseline opioids and provide short-acting IV opioids as needed
- Switch immediately to naloxone infusion
- Administer large benzodiazepine doses instead of opioids
Correct Answer: Continue baseline opioids and provide short-acting IV opioids as needed
Q30. Which monitoring parameter is most critical when initiating opioid therapy in an opioid-naive patient?
- Serum creatinine only
- Respiratory rate and level of sedation
- Liver biopsy
- Blood glucose
Correct Answer: Respiratory rate and level of sedation
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