Structure and uses of acetyl salicylic acid MCQs With Answer

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Structure and uses of acetyl salicylic acid MCQs With Answer

Acetyl salicylic acid (aspirin) is a cornerstone NSAID studied extensively in B. Pharm curricula for its chemical structure, synthesis, pharmacology, and clinical uses. Understanding its 2-(acetyloxy)benzoic acid structure—featuring an esterified phenolic hydroxyl and a free carboxyl group—explains stability, hydrolysis, and reactivity. Key pharmaceutical topics include mechanism of action (irreversible COX acetylation), pharmacokinetics, dosage forms (enteric-coated, tablets), common therapeutic uses (analgesic, antipyretic, anti-inflammatory, antiplatelet), side effects and drug interactions, and analytical assay methods. These MCQs focus on deeper conceptual and practical aspects relevant to B. Pharm students. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the IUPAC name of acetyl salicylic acid?

  • 2-(acetyloxy)benzoic acid
  • o-hydroxybenzoic acid
  • acetylsalicylate sodium
  • 2-hydroxybenzoic acid

Correct Answer: 2-(acetyloxy)benzoic acid

Q2. Which functional groups are present in acetyl salicylic acid?

  • Ester and carboxylic acid
  • Ether and aldehyde
  • Amide and amine
  • Thiol and ketone

Correct Answer: Ester and carboxylic acid

Q3. The molecular formula of aspirin (acetyl salicylic acid) is:

  • C9H8O4
  • C7H6O3
  • C8H10O2
  • C9H10O4

Correct Answer: C9H8O4

Q4. The approximate molecular weight of acetyl salicylic acid is:

  • 180.16 g/mol
  • 210.23 g/mol
  • 152.12 g/mol
  • 198.19 g/mol

Correct Answer: 180.16 g/mol

Q5. Which reagent is commonly used to synthesize aspirin from salicylic acid?

  • Acetic anhydride
  • Hydrochloric acid
  • Sodium hydroxide
  • Benzoyl chloride

Correct Answer: Acetic anhydride

Q6. The key step in aspirin synthesis is:

  • Acetylation of the phenolic hydroxyl group
  • Nitration of the aromatic ring
  • Oxidation of the carboxyl group
  • Reduction of the ester group

Correct Answer: Acetylation of the phenolic hydroxyl group

Q7. Aspirin exerts its primary pharmacological effect by:

  • Irreversibly acetylating cyclooxygenase (COX) enzymes
  • Blocking histamine H1 receptors
  • Inhibiting monoamine oxidase
  • Activating opioid receptors

Correct Answer: Irreversibly acetylating cyclooxygenase (COX) enzymes

Q8. Low-dose aspirin is widely used for:

  • Antiplatelet therapy to reduce thrombotic risk
  • Long-term high-dose anti-inflammatory therapy
  • Antibiotic prophylaxis
  • Anti-viral treatment

Correct Answer: Antiplatelet therapy to reduce thrombotic risk

Q9. Aspirin is classified pharmacologically as a:

  • Nonsteroidal anti-inflammatory drug (NSAID)
  • Corticosteroid
  • Beta-blocker
  • Proton pump inhibitor

Correct Answer: Nonsteroidal anti-inflammatory drug (NSAID)

Q10. Which metabolite results from hydrolysis of aspirin in vivo?

  • Salicylic acid
  • Benzoic acid
  • Acetic acid only
  • Phenylacetic acid

Correct Answer: Salicylic acid

Q11. The acetyl group in aspirin is responsible for:

  • Irreversible inhibition of COX by acetylating serine in the active site
  • Increasing water solubility dramatically
  • Acting as a prodrug that is inactive until removed
  • Binding to hemoglobin preferentially

Correct Answer: Irreversible inhibition of COX by acetylating serine in the active site

Q12. Which statement about aspirin’s acid dissociation constant (pKa) is true?

  • pKa ≈ 3.5, indicating a relatively acidic carboxyl group
  • pKa ≈ 7.4, matching physiological pH
  • pKa ≈ 9.5, indicating a weak acid
  • pKa ≈ 1.0, indicating a very strong acid

Correct Answer: pKa ≈ 3.5, indicating a relatively acidic carboxyl group

Q13. Major adverse effects of aspirin therapy include:

  • Gastrointestinal irritation, bleeding, and ulcers
  • Renal carcinoma
  • Hyperpigmentation of the skin
  • Immune suppression leading to infections

Correct Answer: Gastrointestinal irritation, bleeding, and ulcers

Q14. Aspirin should be avoided in children with viral infections due to risk of:

  • Reye’s syndrome
  • Anaphylactic shock
  • Growth retardation
  • Diabetes mellitus

Correct Answer: Reye’s syndrome

Q15. Enteric-coated aspirin tablets are designed to:

  • Reduce gastric irritation by delaying release until the intestine
  • Increase taste masking in the mouth
  • Provide intravenous administration
  • Enhance rapid sublingual absorption

Correct Answer: Reduce gastric irritation by delaying release until the intestine

Q16. Which analytical method is preferred for precise quantification of aspirin in formulations?

  • High-performance liquid chromatography (HPLC)
  • Thin-layer chromatography (TLC)
  • Paper chromatography
  • Flame photometry

Correct Answer: High-performance liquid chromatography (HPLC)

Q17. In IR spectroscopy of aspirin, the ester carbonyl stretch appears near:

  • 1750 cm⁻¹
  • 1600 cm⁻¹
  • 1200 cm⁻¹
  • 3200–3600 cm⁻¹

Correct Answer: 1750 cm⁻¹

Q18. The primary route of elimination for salicylate metabolites is:

  • Renal excretion after hepatic metabolism and conjugation
  • Exhalation via lungs unchanged
  • Excretion in bile unchanged
  • Sequestration in adipose tissue long-term

Correct Answer: Renal excretion after hepatic metabolism and conjugation

Q19. Protein binding of salicylates in plasma is generally:

  • High (approximately 80–90%) at therapeutic doses
  • Negligible (<10%)
  • Exactly 50%
  • Variable but always below 20%

Correct Answer: High (approximately 80–90%) at therapeutic doses

Q20. Which electrolyte imbalance is classically associated with acute salicylate toxicity?

  • Respiratory alkalosis followed by metabolic acidosis
  • Metabolic alkalosis only
  • Hypokalemic alkalosis exclusively
  • Pure respiratory acidosis

Correct Answer: Respiratory alkalosis followed by metabolic acidosis

Q21. Aspirin’s antiplatelet effect is due to inhibition of:

  • Thromboxane A2 synthesis in platelets
  • Fibrinogen conversion to fibrin
  • Platelet ADP receptor permanently
  • Vitamin K epoxide reductase

Correct Answer: Thromboxane A2 synthesis in platelets

Q22. Which patient group should use aspirin with caution or avoid it?

  • Patients with peptic ulcer disease
  • Patients with seasonal allergies only
  • Patients with vitamin C deficiency exclusively
  • Patients with eczema without GI history

Correct Answer: Patients with peptic ulcer disease

Q23. The smell of vinegar in degraded aspirin tablets indicates:

  • Hydrolysis producing acetic acid
  • Oxidation producing acetic anhydride
  • Formation of pyridine derivatives
  • Contamination with ethanol

Correct Answer: Hydrolysis producing acetic acid

Q24. Which chemical test can be used for qualitative detection of salicylates?

  • Ferric chloride test (blue/violet color)
  • Benedict’s test
  • Biuret test
  • Coagulation test

Correct Answer: Ferric chloride test (blue/violet color)

Q25. Aspirin is chemically unstable in:

  • Moist alkaline conditions causing ester hydrolysis
  • Dry acidic conditions only
  • Completely inert environments
  • Presence of metallic gold

Correct Answer: Moist alkaline conditions causing ester hydrolysis

Q26. Which NMR signal is characteristic of the acetyl methyl group in aspirin?

  • Singlet near 2.3 ppm
  • Triplet near 7.5 ppm
  • Doublet near 9.8 ppm
  • Multiplet near 4.5 ppm

Correct Answer: Singlet near 2.3 ppm

Q27. Aspirin overdose management may include:

  • Alkalinization of urine to enhance salicylate excretion
  • Administration of aspirin antidote naloxone
  • Cooling the patient with ice water immersion only
  • Immediate dialysis in every minor overdose

Correct Answer: Alkalinization of urine to enhance salicylate excretion

Q28. Which co-administered drug increases bleeding risk with aspirin?

  • Warfarin
  • Acetaminophen (paracetamol)
  • Vitamin C
  • Metformin

Correct Answer: Warfarin

Q29. Aspirin’s anti-inflammatory effects at clinical doses are primarily due to:

  • Inhibition of prostaglandin synthesis
  • Stimulation of leukotriene production
  • Direct antimicrobial activity
  • Blocking calcium channels in smooth muscle

Correct Answer: Inhibition of prostaglandin synthesis

Q30. Which formulation reduces aspirin-induced gastric mucosal irritation most effectively?

  • Enteric-coated tablet
  • Immediate-release plain tablet
  • Intramuscular oil suspension
  • Sublingual chewable tablet

Correct Answer: Enteric-coated tablet

Q31. Aspirin is considered irreversible COX inhibitor because it:

  • Acetylates a serine residue on the enzyme
  • Forms a reversible hydrogen bond only
  • Is rapidly metabolized before binding
  • Shears the enzyme into fragments

Correct Answer: Acetylates a serine residue on the enzyme

Q32. In quality control, assay of aspirin tablets can be performed by:

  • Titrimetric analysis after hydrolysis to salicylic acid
  • Counting tablets only
  • Measuring tablet hardness alone
  • Using osmometry exclusively

Correct Answer: Titrimetric analysis after hydrolysis to salicylic acid

Q33. Which is a common sign of chronic salicylate toxicity?

  • Tinnitus
  • Hypothermia only
  • Painless jaundice only
  • Marked bradycardia exclusively

Correct Answer: Tinnitus

Q34. Aspirin’s analgesic effect is largely due to:

  • Reduction of peripheral prostaglandin synthesis sensitizing nociceptors
  • Direct blockade of sodium channels in neurons
  • Binding to opioid receptors centrally
  • Increasing serotonin release from platelets

Correct Answer: Reduction of peripheral prostaglandin synthesis sensitizing nociceptors

Q35. Which statement about aspirin and pregnancy is correct?

  • High-dose aspirin is contraindicated especially near term due to bleeding risk
  • Aspirin is recommended as an analgesic of first choice in all trimesters
  • Aspirin causes teratogenic limb defects commonly
  • Aspirin is completely safe during labor

Correct Answer: High-dose aspirin is contraindicated especially near term due to bleeding risk

Q36. Which form of aspirin is most likely to show reduced bioavailability if chewed?

  • Enteric-coated aspirin
  • Plain immediate-release tablet
  • Sublingual aspirin wafer
  • Aspirin solution for injection

Correct Answer: Enteric-coated aspirin

Q37. Hydrolysis of aspirin yields salicylic acid and which other product?

  • Acetic acid
  • Formic acid
  • Benzoic acid
  • Propionic acid

Correct Answer: Acetic acid

Q38. Aspirin’s effect on platelets lasts for:

  • The life of the platelet (approximately 7–10 days)
  • Only 1 hour
  • 12 minutes
  • It has no effect on platelets

Correct Answer: The life of the platelet (approximately 7–10 days)

Q39. Which wavelength region is useful for UV spectrophotometric assay of aspirin after hydrolysis?

  • ~297 nm for salicylic acid
  • ~500 nm only
  • ~700–800 nm near-infrared
  • ~1900 nm far IR

Correct Answer: ~297 nm for salicylic acid

Q40. Which statement about aspirin and asthma is true?

  • Some asthmatic patients may develop bronchospasm (aspirin-exacerbated respiratory disease)
  • Aspirin cures asthma in most patients
  • Aspirin has no respiratory effects whatsoever
  • Aspirin is a first-line therapy for exercise-induced asthma

Correct Answer: Some asthmatic patients may develop bronchospasm (aspirin-exacerbated respiratory disease)

Q41. Aspirin is often avoided with which diuretic due to increased risk of:

  • Loop diuretics like furosemide due to reduced renal prostaglandin-mediated perfusion and nephrotoxicity
  • Thiazide diuretics due to potassium overload only
  • Carbonic anhydrase inhibitors due to alkalosis exclusively
  • Mannitol due to hyperglycemia

Correct Answer: Loop diuretics like furosemide due to reduced renal prostaglandin-mediated perfusion and nephrotoxicity

Q42. Which compound is NOT a product of aspirin degradation?

  • Phenol
  • Salicylic acid
  • Acetic acid
  • None of the above

Correct Answer: Phenol

Q43. In industrial manufacture, the esterification of salicylic acid to aspirin is typically catalyzed by:

  • Acid catalysts such as sulfuric or phosphoric acid or using acetic anhydride itself
  • Strong bases like sodium hydroxide exclusively
  • Enzymatic catalysts only
  • Light without catalyst

Correct Answer: Acid catalysts such as sulfuric or phosphoric acid or using acetic anhydride itself

Q44. Which of the following best describes aspirin’s solubility in water at room temperature?

  • Poorly soluble
  • Highly soluble
  • Completely insoluble
  • Soluble only in organic solvents like hexane

Correct Answer: Poorly soluble

Q45. Which laboratory method differentiates aspirin from salicylic acid directly?

  • Hydrolysis followed by ferric chloride test to detect salicylic acid
  • Melting point that is identical for both
  • Simple odor test only
  • They cannot be differentiated by any test

Correct Answer: Hydrolysis followed by ferric chloride test to detect salicylic acid

Q46. Long-term high-dose aspirin therapy may lead to which acid–base disturbance?

  • Mixed respiratory alkalosis and metabolic acidosis
  • Pure metabolic alkalosis only
  • Primary respiratory acidosis exclusively
  • No disturbance in acid–base balance ever

Correct Answer: Mixed respiratory alkalosis and metabolic acidosis

Q47. Aspirin’s anti-thrombotic benefit is primarily used in prevention of:

  • Myocardial infarction and ischemic stroke
  • Bacterial endocarditis only
  • Epilepsy seizures
  • Viral hepatitis exclusively

Correct Answer: Myocardial infarction and ischemic stroke

Q48. Which excipient choice is important to minimize aspirin hydrolysis in tablets?

  • Use of moisture-protective fillers and desiccants
  • Adding strong bases to formulation
  • Including large amounts of water as excipient
  • Using only hygroscopic excipients

Correct Answer: Use of moisture-protective fillers and desiccants

Q49. Which statement about aspirin as a prodrug is correct?

  • Aspirin is not a classical prodrug; it is active itself and also yields active salicylic acid after hydrolysis
  • Aspirin is an inactive compound until salicylate is formed and has no intrinsic activity
  • Aspirin is a peptide prodrug requiring enzymatic cleavage to an amino acid
  • Aspirin must be reduced to an alcohol to act

Correct Answer: Aspirin is not a classical prodrug; it is active itself and also yields active salicylic acid after hydrolysis

Q50. Which patient counseling point is most appropriate for oral aspirin tablets?

  • Take with food or after meals to reduce gastric irritation
  • Always take on an empty stomach for best absorption
  • Crush enteric-coated tablets to speed action
  • Combine with other NSAIDs daily for better antiplatelet effect

Correct Answer: Take with food or after meals to reduce gastric irritation

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