Alkaloids – Quinine MCQs With Answer

Alkaloids – Quinine MCQs With Answer

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Alkaloids – Quinine MCQs With Answer
Quinine is a classic quinoline alkaloid derived from Cinchona bark, central to antimalarial pharmacology and B. Pharm curricula. This introduction covers quinine’s chemical structure, stereochemistry, salt forms, extraction, analytical assay (HPLC), mechanism against Plasmodium (inhibition of heme polymerization), pharmacokinetics, drug interactions (CYP3A4), and adverse effects such as cinchonism, hypoglycemia and hemolysis. Understanding quinine’s clinical uses, resistance mechanisms and safe IV administration is vital for safe therapeutics. These focused, exam-oriented points will help you master core concepts and practical implications. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. What is the primary natural source of quinine?

  • Cinchona bark (Cinchona species)
  • Digitalis leaves
  • Willow bark
  • Ergot fungus

Correct Answer: Cinchona bark (Cinchona species)

Q2. Quinine belongs to which class of alkaloids?

  • Quinoline alkaloid
  • Tropane alkaloid
  • Indole alkaloid
  • Pyrrolizidine alkaloid

Correct Answer: Quinoline alkaloid

Q3. What is the molecular formula of quinine?

  • C17H19NO3
  • C20H24N2O2
  • C21H26N2O3
  • C19H22N2O2

Correct Answer: C20H24N2O2

Q4. What is the stereochemical relationship between quinine and quinidine?

  • They are enantiomers
  • They are diastereomers
  • They are constitutional isomers
  • They are identical compounds

Correct Answer: They are diastereomers

Q5. Which salt form of quinine is commonly used in oral dosage forms?

  • Quinine sulfate
  • Quinine nitrate
  • Quinine phosphate
  • Quinine acetate

Correct Answer: Quinine sulfate

Q6. What is the primary antimalarial mechanism of quinine?

  • Inhibition of hemozoin formation (heme polymerization)
  • Blockade of folate synthesis in Plasmodium
  • Inhibition of protein synthesis at the ribosome
  • Disruption of parasite DNA gyrase

Correct Answer: Inhibition of hemozoin formation (heme polymerization)

Q7. Which clinical syndrome is classically associated with quinine toxicity?

  • Cinchonism
  • Serotonin syndrome
  • Nephrotic syndrome
  • Anticholinergic syndrome

Correct Answer: Cinchonism

Q8. How does quinine cause hypoglycemia as an adverse effect?

  • Stimulates pancreatic insulin secretion
  • Inhibits hepatic gluconeogenesis directly
  • Blocks intestinal glucose absorption
  • Causes renal glucose loss

Correct Answer: Stimulates pancreatic insulin secretion

Q9. Which severe hemolytic complication has been historically linked to quinine therapy?

  • Blackwater fever (massive hemolysis and hemoglobinuria)
  • Hemolytic uremic syndrome
  • Aplastic anemia
  • Immune thrombocytopenia

Correct Answer: Blackwater fever (massive hemolysis and hemoglobinuria)

Q10. Which cardiac effect can occur with quinine overdose or rapid IV administration?

  • QT prolongation and potential torsades de pointes
  • Marked hypertension and stroke
  • Bradycardia without conduction changes only
  • Atrial septal defect

Correct Answer: QT prolongation and potential torsades de pointes

Q11. Which drug interaction is most important because it increases quinine plasma concentration?

  • CYP3A4 inhibitors (e.g., ketoconazole)
  • Nonsteroidal anti-inflammatory drugs
  • Antacids containing magnesium
  • Vitamin C supplements

Correct Answer: CYP3A4 inhibitors (e.g., ketoconazole)

Q12. Regarding use in pregnancy, which statement is correct for quinine?

  • Quinine can be used to treat severe malaria in pregnancy
  • Quinine is absolutely contraindicated in all trimesters
  • Quinine is only used as a topical agent in pregnancy
  • Quinine causes definite teratogenic malformations and is never used

Correct Answer: Quinine can be used to treat severe malaria in pregnancy

Q13. Which analytical method is commonly used for quantifying quinine in plasma?

  • High-performance liquid chromatography (HPLC)
  • Gravimetric titration
  • Paper chromatography
  • Colorimetric ferric test only

Correct Answer: High-performance liquid chromatography (HPLC)

Q14. What is the approximate elimination half-life of quinine in adults?

  • About 11 hours
  • About 1 hour
  • About 72 hours
  • About 5 minutes

Correct Answer: About 11 hours

Q15. Which statement best describes quinine’s plasma protein binding?

  • It exhibits extensive plasma protein binding (~70%)
  • It is not bound to plasma proteins at all
  • It is irreversibly bound to albumin only
  • It binds exclusively to globulins

Correct Answer: It exhibits extensive plasma protein binding (~70%)

Q16. What is an important precaution when administering intravenous quinine?

  • Administer slowly to avoid hypotension and arrhythmias
  • Give as an undiluted rapid bolus for fast action
  • Always mix with calcium-containing solutions
  • Administer only by intramuscular injection

Correct Answer: Administer slowly to avoid hypotension and arrhythmias

Q17. Which parasite genetic change is commonly implicated in quinine resistance?

  • Plasmodium falciparum pfmdr1 gene mutations/amplification
  • Human CYP2D6 gene polymorphism
  • Plasmodium vivax ribosomal mutation
  • Loss of human hemoglobin gene

Correct Answer: Plasmodium falciparum pfmdr1 gene mutations/amplification

Q18. Which non-malarial indication has historically been treated with quinine (though not recommended now)?

  • Nocturnal leg cramps
  • Hypertension
  • Type 2 diabetes
  • Hyperthyroidism

Correct Answer: Nocturnal leg cramps

Q19. Which is a major metabolite of quinine formed in the liver?

  • 3-hydroxyquinine
  • 6-aminopenicillanic acid
  • N-desmethylchloroquine
  • Sulfamethoxazole

Correct Answer: 3-hydroxyquinine

Q20. In which clinical scenario is therapeutic drug monitoring of quinine most likely indicated?

  • Severe malaria or renal/hepatic impairment to avoid toxicity
  • Routine treatment of common cold
  • Topical application for skin rash
  • Prevention of motion sickness only

Correct Answer: Severe malaria or renal/hepatic impairment to avoid toxicity

Q21. Which organ is primarily responsible for quinine metabolism?

  • Liver (hepatic metabolism)
  • Kidney (exclusive metabolism)
  • Pancreas
  • Lungs

Correct Answer: Liver (hepatic metabolism)

Q22. Which oral formulation of quinine is commonly prescribed?

  • Oral quinine sulfate tablets
  • Quinine transdermal patch
  • Quinine inhalation powder
  • Quinine ophthalmic drops

Correct Answer: Oral quinine sulfate tablets

Q23. Quinine is contraindicated in patients with which prior adverse reaction?

  • History of quinine-induced thrombocytopenia or severe hypersensitivity
  • History of seasonal allergies to pollen only
  • Prior appendectomy
  • Controlled hypothyroidism on levothyroxine

Correct Answer: History of quinine-induced thrombocytopenia or severe hypersensitivity

Q24. Which clinical feature is characteristic of cinchonism?

  • Tinnitus and visual disturbances
  • Peripheral neuropathy without sensory loss
  • Isolated hypertension only
  • Severe pruritic rash exclusively

Correct Answer: Tinnitus and visual disturbances

Q25. Which statement correctly describes quinine solubility?

  • Quinine base is poorly water-soluble; quinine salts (e.g., sulfate) are water-soluble
  • Quinine base is freely soluble in water without forming salts
  • All quinine salts are insoluble in water
  • Quinine is only soluble in nonpolar solvents and never in alcohol

Correct Answer: Quinine base is poorly water-soluble; quinine salts (e.g., sulfate) are water-soluble

Q26. What is quinine’s status on global treatment lists?

  • Included on the WHO Essential Medicines List for severe malaria
  • Prohibited by the WHO for all clinical use
  • Only available as an over-the-counter supplement
  • Removed entirely from all formularies worldwide

Correct Answer: Included on the WHO Essential Medicines List for severe malaria

Q27. Which structural features are present in the quinine molecule?

  • Quinoline nucleus and a quinuclidine bicyclic amine with a methoxy substituent
  • Indole ring fused to a tropane skeleton
  • Simple benzene ring with a single hydroxyl group only
  • Large peptide chain with disulfide bridges

Correct Answer: Quinoline nucleus and a quinuclidine bicyclic amine with a methoxy substituent

Q28. What are clinical features of severe quinine overdose?

  • Severe cinchonism, hypotension and life-threatening arrhythmias
  • Isolated skin discoloration only
  • Improved alertness and hypertension only
  • Chronic cough without systemic signs

Correct Answer: Severe cinchonism, hypotension and life-threatening arrhythmias

Q29. Compared to quinidine, quinine is primarily characterized by which pharmacological emphasis?

  • Quinine has stronger antimalarial activity; quinidine has stronger antiarrhythmic effects
  • Quinine is purely an antiarrhythmic and has no antimalarial action
  • Both compounds have identical therapeutic profiles
  • Quinine is only used as an anesthetic agent

Correct Answer: Quinine has stronger antimalarial activity; quinidine has stronger antiarrhythmic effects

Q30. Which solvent condition is traditionally used for extracting quinine from Cinchona bark?

  • Acidified ethanol (acidified alcohol) extraction
  • Pure hexane extraction only
  • Supercritical CO2 with no modifiers
  • Cold distilled water without acidification

Correct Answer: Acidified ethanol (acidified alcohol) extraction

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