Nitroglycerin MCQs With Answer provides B. Pharm students a focused, keyword-rich review of nitroglycerin pharmacology, mechanism of action, pharmacokinetics, clinical uses, adverse effects, tolerance, and drug interactions. This concise introduction emphasizes bioactivation by mitochondrial ALDH2, NO–cGMP signaling, predominant venodilatory effects that reduce preload, and practical points on sublingual, transdermal, and IV formulations. Clinical relevance includes angina management, acute pulmonary edema, contraindications with PDE5 inhibitors, and strategies to prevent tolerance. Clear, exam-oriented questions reinforce dosing, monitoring, stability, and combination therapy in heart failure. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which chemical class does nitroglycerin belong to?
- Organic nitrate
- Calcium channel blocker
- Beta-adrenergic agonist
- ACE inhibitor
Correct Answer: Organic nitrate
Q2. What is the primary mechanism by which nitroglycerin produces vasodilation?
- Blockade of L-type calcium channels
- Activation of guanylate cyclase increasing cGMP
- Inhibition of angiotensin-converting enzyme
- Beta-2 adrenergic receptor stimulation
Correct Answer: Activation of guanylate cyclase increasing cGMP
Q3. Which enzyme is most important for the bioactivation of nitroglycerin to release nitric oxide?
- Mitochondrial aldehyde dehydrogenase (ALDH2)
- CYP3A4
- Monoamine oxidase
- Glutathione S-transferase
Correct Answer: Mitochondrial aldehyde dehydrogenase (ALDH2)
Q4. Hemodynamically, the predominant effect of therapeutic doses of nitroglycerin is:
- Arteriolar dilation reducing afterload
- Venodilation reducing preload
- Increased myocardial contractility
- Increased heart rate via beta stimulation
Correct Answer: Venodilation reducing preload
Q5. Which route provides the most rapid onset for relief of acute angina?
- Sublingual tablet or spray
- Oral extended-release tablet
- Transdermal patch
- Topical ointment
Correct Answer: Sublingual tablet or spray
Q6. Typical onset of action for sublingual nitroglycerin is approximately:
- 1–3 minutes
- 30–60 minutes
- 6–8 hours
- 24–48 hours
Correct Answer: 1–3 minutes
Q7. The most common adverse effect experienced by patients taking nitroglycerin is:
- Headache
- Renal failure
- Hyperkalemia
- Pulmonary fibrosis
Correct Answer: Headache
Q8. Nitroglycerin is absolutely contraindicated with which of the following medications due to risk of severe hypotension?
- Sildenafil (a PDE5 inhibitor)
- Metformin
- Amoxicillin
- Warfarin
Correct Answer: Sildenafil (a PDE5 inhibitor)
Q9. Which mechanism contributes to development of nitrate tolerance during continuous nitroglycerin therapy?
- Depletion of sulfhydryl groups and reduced ALDH2-mediated bioactivation
- Upregulation of nitric oxide synthase increasing NO levels
- Enhanced renal clearance of nitroglycerin
- Autoimmune neutralization of the drug
Correct Answer: Depletion of sulfhydryl groups and reduced ALDH2-mediated bioactivation
Q10. A practical strategy to minimize nitrate tolerance in chronic transdermal therapy is:
- Provide a daily nitrate-free interval (eg, remove patch at night)
- Increase dose continuously over weeks
- Combine with a PDE5 inhibitor daily
- Use continuous 24-hour infusion without interruption
Correct Answer: Provide a daily nitrate-free interval (eg, remove patch at night)
Q11. Nitroglycerin undergoes significant first-pass metabolism primarily in which organ?
- Liver
- Kidney
- Lung
- Pancreas
Correct Answer: Liver
Q12. Compared to nitroglycerin, isosorbide mononitrate (ISMN) differs clinically because it:
- Has longer duration and does not undergo extensive first-pass metabolism
- Is only available as an IV formulation
- Has a much faster onset than sublingual nitroglycerin
- Is contraindicated in heart failure
Correct Answer: Has longer duration and does not undergo extensive first-pass metabolism
Q13. Intravenous nitroglycerin is particularly useful in which acute condition?
- Acute pulmonary edema with severe hypertension
- Uncomplicated urinary tract infection
- Stable chronic asthma
- Acute appendicitis
Correct Answer: Acute pulmonary edema with severe hypertension
Q14. Nitroglycerin can relieve coronary vasospasm because it:
- Dilates epicardial coronary arteries and reduces smooth muscle tone
- Blocks platelet aggregation directly
- Inhibits angiotensin II formation
- Stimulates alpha-1 adrenergic receptors
Correct Answer: Dilates epicardial coronary arteries and reduces smooth muscle tone
Q15. Which of the following is a rare but reported adverse effect of high-dose nitrates?
- Methemoglobinemia
- Hyperthyroidism
- Osteoporosis
- Pancreatitis
Correct Answer: Methemoglobinemia
Q16. Nitroglycerin should be used with caution or is contraindicated in patients with:
- Hypertrophic obstructive cardiomyopathy due to worsening outflow obstruction
- Type 2 diabetes mellitus without cardiac disease
- Mild seasonal allergies
- Compensated hypothyroidism
Correct Answer: Hypertrophic obstructive cardiomyopathy due to worsening outflow obstruction
Q17. For optimal storage and potency, nitroglycerin tablets should be kept:
- In original amber glass container away from heat and light
- In a clear plastic vial in the bathroom
- Exposed to air on a countertop
- Frozen for long-term storage
Correct Answer: In original amber glass container away from heat and light
Q18. Which vasodilator is commonly combined with nitrates in chronic heart failure to improve outcomes in selected patients?
- Hydralazine
- Verapamil
- Digoxin
- Furosemide
Correct Answer: Hydralazine
Q19. The most effective clinical strategy to prevent tolerance to nitrates is to:
- Provide intermittent dosing with a daily nitrate-free interval
- Double the dose each day
- Add a PDE5 inhibitor to the regimen
- Limit therapy only to topical formulations
Correct Answer: Provide intermittent dosing with a daily nitrate-free interval
Q20. A transdermal nitroglycerin patch typically provides sustained delivery for approximately:
- 24 hours
- 5 minutes
- 1 hour
- 7 days
Correct Answer: 24 hours
Q21. At higher therapeutic doses, nitroglycerin also reduces afterload by dilating:
- Arterioles
- The glomerulus
- Bronchioles
- Capillary basement membrane
Correct Answer: Arterioles
Q22. cGMP generated by nitroglycerin signaling causes smooth muscle relaxation primarily via:
- Activation of myosin light chain phosphatase leading to dephosphorylation of myosin light chains
- Inhibition of sodium–potassium ATPase
- Increased intracellular calcium release
- Enhanced actin polymerization
Correct Answer: Activation of myosin light chain phosphatase leading to dephosphorylation of myosin light chains
Q23. A commonly recommended sublingual dose for relief of acute angina is:
- 0.3–0.6 mg every 5 minutes up to three doses
- 50 mg once daily
- 10 mg/kg every 4 hours
- 100 mg IV bolus once
Correct Answer: 0.3–0.6 mg every 5 minutes up to three doses
Q24. Which parameter is most important to monitor when initiating nitroglycerin therapy?
- Blood pressure
- Serum creatinine weekly
- Liver enzymes monthly
- Fasting glucose daily
Correct Answer: Blood pressure
Q25. Nitroglycerin preferentially dilates veins more than arteries because veins:
- Have greater capacity and are more sensitive to NO-mediated relaxation
- Contain no smooth muscle
- Have thicker tunica media than arteries
- Are innervated only by sympathetic fibers
Correct Answer: Have greater capacity and are more sensitive to NO-mediated relaxation
Q26. Which of the following is NOT a common pharmaceutical formulation of nitroglycerin?
- Inhalation aerosol
- Sublingual tablets or spray
- Transdermal patches
- Intravenous infusion
Correct Answer: Inhalation aerosol
Q27. When given by intravenous infusion, the onset of nitroglycerin’s vasodilatory effect is usually:
- Within 1–2 minutes
- After 24 hours
- After 7–10 days
- Not observed with IV administration
Correct Answer: Within 1–2 minutes
Q28. The plasma half-life of nitroglycerin is approximately:
- 1–4 minutes
- 12–24 hours
- 3–5 days
- Several weeks
Correct Answer: 1–4 minutes
Q29. Reflex tachycardia seen with nitroglycerin results mainly from:
- Baroreceptor-mediated sympathetic activation due to blood pressure reduction
- Direct beta-1 receptor agonism by nitroglycerin
- Inhibition of vagal tone by nitroglycerin metabolites
- Excessive sodium retention
Correct Answer: Baroreceptor-mediated sympathetic activation due to blood pressure reduction
Q30. Genetic polymorphism in which enzyme can reduce clinical responsiveness to nitroglycerin in some populations?
- Mitochondrial aldehyde dehydrogenase (ALDH2)
- CYP2D6
- Glucose-6-phosphate dehydrogenase
- ACE
Correct Answer: Mitochondrial aldehyde dehydrogenase (ALDH2)
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