Morphine sulphate MCQs With Answer provides B. Pharm students a targeted, Student-friendly review of morphine’s pharmacology, clinical uses, adverse effects, metabolism and safe handling. This introduction highlights essential topics: mu-opioid receptor mechanism, hepatic glucuronidation to M6G/M3G, routes and formulations, dosing principles, tolerance and dependence, overdose reversal with naloxone, drug interactions, and monitoring for respiratory depression and sedation. The content is written to deepen understanding for exams and clinical application, emphasizing practical aspects such as contraindications, renal dosing considerations and patient counselling. Answers are included to help identify knowledge gaps and reinforce key concepts. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. What is the primary mechanism of action of morphine?
- Inhibition of COX enzymes
- Activation of mu-opioid receptors causing G-protein mediated inhibition of adenylate cyclase
- Blockade of NMDA receptors
- Enhancement of serotonin release
Correct Answer: Activation of mu-opioid receptors causing G-protein mediated inhibition of adenylate cyclase
Q2. Which major metabolite of morphine is primarily responsible for its analgesic activity?
- M3G (morphine-3-glucuronide)
- M6G (morphine-6-glucuronide)
- Normorphine
- Hydromorphone
Correct Answer: M6G (morphine-6-glucuronide)
Q3. Which hepatic enzyme pathway mainly metabolizes morphine?
- CYP3A4-mediated oxidation
- UGT2B7-mediated glucuronidation
- CYP2D6 O-demethylation
- Monoamine oxidase (MAO)
Correct Answer: UGT2B7-mediated glucuronidation
Q4. Why is morphine sulphate commonly supplied as the sulfate salt?
- To make it more lipophilic for CNS penetration
- To increase aqueous solubility suitable for injection
- To increase its oral bioavailability above 90%
- To prevent glucuronidation
Correct Answer: To increase aqueous solubility suitable for injection
Q5. What is the most serious acute adverse effect of morphine that requires monitoring?
- Constipation
- Itching
- Respiratory depression
- Orthostatic hypotension
Correct Answer: Respiratory depression
Q6. Which drug is the standard antidote for morphine overdose?
- Flumazenil
- Naloxone
- Naltrexone
- Atropine
Correct Answer: Naloxone
Q7. Which clinical sign is characteristically seen with therapeutic doses of morphine?
- Mydriasis (dilated pupils)
- Miosis (constricted pupils)
- Skin blanching
- Hyperthermia
Correct Answer: Miosis (constricted pupils)
Q8. In which patient situation is morphine use particularly cautioned due to risk of worsening intracranial pressure or masking clinical signs?
- Patients with migraine
- Patients with head injury or raised intracranial pressure
- Patients with controlled hypertension
- Patients with peripheral neuropathy
Correct Answer: Patients with head injury or raised intracranial pressure
Q9. Morphine exerts most of its analgesic effects via which opioid receptor subtype?
- Delta (δ) receptor
- Kappa (κ) receptor
- Mu (μ) receptor
- Nociceptin receptor
Correct Answer: Mu (μ) receptor
Q10. Development of tolerance to morphine analgesia is mainly due to which process?
- Increased renal clearance
- Receptor desensitization and neuroadaptive changes
- Enhanced first-pass metabolism
- Increased blood–brain barrier permeability
Correct Answer: Receptor desensitization and neuroadaptive changes
Q11. Which of the following effects of morphine is partly mediated by histamine release?
- Analgesia
- Bradycardia
- Pruritus (itching) and urticaria
- Hypertension
Correct Answer: Pruritus (itching) and urticaria
Q12. In the United States, morphine is classified under which controlled substance schedule?
- Schedule I
- Schedule II
- Schedule III
- Schedule IV
Correct Answer: Schedule II
Q13. Which administration method allows patient-controlled titration of morphine for acute post-operative pain?
- Oral immediate release tablets
- Patient-controlled analgesia (PCA) pump via IV
- Transdermal patch
- Intramuscular single injection
Correct Answer: Patient-controlled analgesia (PCA) pump via IV
Q14. Why is oral morphine bioavailability relatively low?
- Poor intestinal absorption due to high molecular weight
- Extensive hepatic first-pass metabolism
- Degradation by gastric acid
- Inactivation by pancreatic enzymes
Correct Answer: Extensive hepatic first-pass metabolism
Q15. Which metabolite accumulation is most associated with enhanced analgesic effect but may accumulate in renal failure?
- M3G causing analgesia
- M6G causing analgesia
- Normorphine causing analgesia
- Hydroxymorphine causing analgesia
Correct Answer: M6G causing analgesia
Q16. The primary route of excretion for morphine and its glucuronide metabolites is:
- Biliary excretion into feces
- Renal excretion in urine
- Exhalation via lungs
- Sweat and saliva
Correct Answer: Renal excretion in urine
Q17. The approximate pKa of morphine, relevant to its ionization at physiological pH, is closest to:
- 4.0
- 7.9–8.0
- 10.5
- 2.1
Correct Answer: 7.9–8.0
Q18. Which gastrointestinal effect is characteristically produced by morphine?
- Increased intestinal motility causing diarrhea
- Decreased gastric emptying and constipation
- No significant effect on GI motility
- Enhanced bile secretion
Correct Answer: Decreased gastric emptying and constipation
Q19. Is morphine recommended for initial pain relief in acute myocardial infarction?
- No, it is contraindicated in all MI cases
- Yes, for severe pain and anxiety when indicated
- Only as an oral outpatient medication
- Only in combination with NSAIDs
Correct Answer: Yes, for severe pain and anxiety when indicated
Q20. Combining morphine with which class of drugs markedly increases risk of profound sedation and respiratory depression?
- Selective beta blockers
- Benzodiazepines and other CNS depressants
- Proton pump inhibitors
- Vitamin supplements
Correct Answer: Benzodiazepines and other CNS depressants
Q21. After IV administration, the onset of analgesic action of morphine is typically:
- 30–60 minutes
- 2–5 minutes
- 12–24 hours
- Immediate and permanent
Correct Answer: 2–5 minutes
Q22. The usual duration of analgesic effect of a single parenteral dose of morphine is approximately:
- 30 minutes
- 3–4 hours
- 24–48 hours
- Greater than 72 hours
Correct Answer: 3–4 hours
Q23. Use of morphine in acute severe bronchospasm is:
- Recommended because it bronchodilates
- Not recommended due to risk of histamine release and respiratory depression
- Indicated as first-line therapy
- Only effective via transdermal route
Correct Answer: Not recommended due to risk of histamine release and respiratory depression
Q24. Which peripheral opioid antagonist is used to treat opioid-induced constipation without reversing central analgesia?
- Naloxone oral solution
- Methylnaltrexone
- Naltrexone oral tablet
- Flumazenil
Correct Answer: Methylnaltrexone
Q25. Opioid receptors, including the mu receptor targeted by morphine, belong to which receptor family?
- Ligand-gated ion channels
- G-protein coupled receptors (GPCRs)
- Nuclear hormone receptors
- Tyrosine kinase receptors
Correct Answer: G-protein coupled receptors (GPCRs)
Q26. Chronic maternal morphine use during pregnancy most commonly risks what neonatal complication?
- Neonatal abstinence syndrome (withdrawal)
- Neonatal hyperglycemia
- Congenital cardiac malformations exclusively
- No neonatal effects
Correct Answer: Neonatal abstinence syndrome (withdrawal)
Q27. Compared with morphine base, morphine sulphate is more suitable for parenteral use mainly because it:
- Is less potent
- Is more water-soluble and stable for injection
- Has a longer half-life
- Evades renal excretion
Correct Answer: Is more water-soluble and stable for injection
Q28. Which UDP-glucuronosyltransferase isoform predominantly forms morphine-3- and morphine-6-glucuronides?
- UGT1A1
- UGT2B7
- CYP2D6
- MAO-A
Correct Answer: UGT2B7
Q29. Which opioid listed is significantly more potent than morphine on a weight basis?
- Codeine
- Fentanyl
- Tramadol
- Dextromethorphan
Correct Answer: Fentanyl
Q30. Morphine reduces transmission of nociceptive signals partly by inhibiting release of which neurotransmitter from primary afferent neurons?
- Dopamine
- Substance P
- Acetylcholine
- Norepinephrine
Correct Answer: Substance P
Q31. Which phenomenon describes increased pain sensitivity after prolonged opioid use?
- Tolerance
- Dependence
- Opioid-induced hyperalgesia
- Withdrawal
Correct Answer: Opioid-induced hyperalgesia
Q32. One therapeutic effect of morphine outside analgesia is suppression of which reflex?
- Cough reflex
- Patellar reflex
- Pupillary light reflex
- Baroreceptor reflex
Correct Answer: Cough reflex
Q33. Morphine is generally not recommended in biliary colic because it can:
- Relieve sphincter spasm
- Cause sphincter of Oddi spasm and worsen pain
- Increase bile production excessively
- Have no effect on biliary tract
Correct Answer: Cause sphincter of Oddi spasm and worsen pain
Q34. Which adverse effect of morphine is most likely to respond to an H1-antihistamine?
- Respiratory depression
- Nausea and vomiting
- Pruritus (itching)
- Constipation
Correct Answer: Pruritus (itching)
Q35. Which route of morphine administration bypasses first-pass hepatic metabolism entirely?
- Oral immediate-release tablets
- Intravenous injection
- Oral sustained-release tablets
- Rectal suppository
Correct Answer: Intravenous injection
Q36. For safe outpatient prescribing, which monitoring parameter is most essential to educate patients about when on morphine therapy?
- Regular blood glucose monitoring
- Monitoring respiratory rate and level of sedation
- Daily platelet counts
- Urine pH testing
Correct Answer: Monitoring respiratory rate and level of sedation
Q37. Which morphine metabolite is more associated with neuroexcitatory side effects such as myoclonus and seizures?
- M6G (morphine-6-glucuronide)
- M3G (morphine-3-glucuronide)
- Normorphine
- Codeine
Correct Answer: M3G (morphine-3-glucuronide)
Q38. Morphine plays a central role in palliative care primarily because it:
- Is a strong anti-inflammatory agent
- Provides effective relief of severe cancer pain
- Is free of adverse effects in chronic use
- Speeds up terminal metabolic processes
Correct Answer: Provides effective relief of severe cancer pain
Q39. Agonism at which opioid receptor subtype is most commonly associated with dysphoria and psychotomimetic effects?
- Mu (μ) receptor
- Delta (δ) receptor
- Kappa (κ) receptor
- Nociceptin receptor
Correct Answer: Kappa (κ) receptor
Q40. Naloxone reverses morphine effects by which pharmacological action?
- Irreversible inhibition of mu receptors
- Competitive antagonism at opioid receptors
- Enhancing opioid metabolism
- Stimulating adenylate cyclase directly
Correct Answer: Competitive antagonism at opioid receptors
Q41. Morphine sulphate is primarily indicated for which level of pain?
- Mild pain responsive to paracetamol
- Moderate-to-severe pain requiring strong opioid analgesia
- Primary headache disorders only
- Asymptomatic chronic conditions
Correct Answer: Moderate-to-severe pain requiring strong opioid analgesia
Q42. Which statement is true regarding anti-inflammatory activity of morphine?
- Morphine has strong anti-inflammatory properties similar to NSAIDs
- Morphine has no significant anti-inflammatory effect
- Morphine inhibits COX-2 selectively
- Morphine increases prostaglandin synthesis
Correct Answer: Morphine has no significant anti-inflammatory effect
Q43. The plasma half-life of morphine in healthy adults is approximately:
- 30 minutes
- 2–4 hours
- 24 hours
- Several days
Correct Answer: 2–4 hours
Q44. Of the following, which route typically provides the slowest onset of analgesia for morphine?
- Intravenous bolus
- Intramuscular injection
- Oral immediate-release
- Subcutaneous injection
Correct Answer: Oral immediate-release
Q45. In patients with severe renal impairment, morphine therapy requires caution because:
- Morphine clearance is increased and efficacy lost
- M6G and M3G metabolites accumulate and may increase toxicity
- Morphine is converted to methadone
- Renal impairment has no effect on morphine pharmacology
Correct Answer: M6G and M3G metabolites accumulate and may increase toxicity
Q46. Compared with morphine, codeine’s analgesic potency is approximately:
- 10 times more potent than morphine
- About one-tenth as potent as morphine
- The same potency as morphine
- Completely inactive as an analgesic
Correct Answer: About one-tenth as potent as morphine
Q47. Which drug is commonly used to treat opioid-induced pruritus caused by morphine?
- Loperamide
- Diphenhydramine (an antihistamine)
- Methadone
- Proton pump inhibitor
Correct Answer: Diphenhydramine (an antihistamine)
Q48. Proper storage and handling of morphine sulphate in a pharmacy requires which of the following?
- Open shelf storage without records
- Secure locked storage and accurate controlled-substance records
- Storage with antibiotics at room temperature
- Freezer storage at −20°C
Correct Answer: Secure locked storage and accurate controlled-substance records
Q49. Long-term opioid therapy with morphine can disrupt endocrine function leading to which effect?
- Increased testosterone and libido
- Hypogonadism with reduced sex hormones
- Hyperthyroidism
- Improved fertility
Correct Answer: Hypogonadism with reduced sex hormones
Q50. Activation of mu-opioid receptors by morphine leads to intracellular signaling primarily via which G-protein and second-messenger change?
- Gs protein activation and increased cAMP
- Gi/Go protein activation and decreased cAMP
- Gq protein activation and increased IP3/DAG
- Tyrosine kinase activation and increased MAPK only
Correct Answer: Gi/Go protein activation and decreased cAMP
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