Ethacrynic acid MCQs With Answer — Ethacrynic acid is a potent loop diuretic studied in B.Pharm pharmacology for its unique mechanism, pharmacokinetics, clinical indications, adverse effects, and drug interactions. Unlike sulfonamide loop diuretics, ethacrynic acid lacks a sulfonamide moiety, making it useful in patients with sulfa allergy. Students should understand its site of action at the Na+-K+-2Cl− cotransporter (NKCC2) in the thick ascending limb, effects on electrolyte homeostasis, risk of ototoxicity, metabolic consequences, dosage forms, and contraindications. Mastery of these concepts aids safe therapeutics and rational drug use. This set of targeted MCQs reinforces mechanism, pharmacology, clinical uses, monitoring parameters, and common interactions. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which transporter is the primary site of action for ethacrynic acid in the nephron?
- Na+-K+-2Cl− cotransporter (NKCC2) in the thick ascending limb
- Na+-Cl− cotransporter in the distal convoluted tubule
- ENaC (epithelial sodium channel) in the collecting duct
- Proximal tubule Na+/H+ exchanger
Correct Answer: Na+-K+-2Cl− cotransporter (NKCC2) in the thick ascending limb
Q2. A major clinical indication for ethacrynic acid is:
- Hypertension as first-line monotherapy in all patients
- Edema associated with congestive heart failure when sulfonamide diuretics are contraindicated
- Chronic management of nephrogenic diabetes insipidus
- Primary treatment of nephrotic syndrome without edema
Correct Answer: Edema associated with congestive heart failure when sulfonamide diuretics are contraindicated
Q3. Compared to furosemide, ethacrynic acid is distinguished chemically by:
- Possession of a sulfonamide group
- Absence of a sulfonamide group
- Being a thiazide derivative
- Being a potassium-sparing steroidal compound
Correct Answer: Absence of a sulfonamide group
Q4. Which electrolyte disturbance is most characteristically caused by ethacrynic acid?
- Hyperkalemia
- Hypokalemia
- Hypercalcemia
- Hypermagnesemia
Correct Answer: Hypokalemia
Q5. Ethacrynic acid can increase the risk of ototoxicity, especially when combined with which drug class?
- ACE inhibitors
- Aminoglycoside antibiotics
- Beta blockers
- Statins
Correct Answer: Aminoglycoside antibiotics
Q6. The diuretic action of ethacrynic acid leads to which effect on urinary calcium excretion?
- Decreased urinary calcium excretion (hypocalciuria)
- Increased urinary calcium excretion (hypercalciuria)
- No change in calcium excretion
- Intermittent fluctuation without predictable trend
Correct Answer: Increased urinary calcium excretion (hypercalciuria)
Q7. Which metabolic acid–base disturbance is most likely with prolonged use of ethacrynic acid?
- Metabolic acidosis
- Metabolic alkalosis
- Respiratory acidosis
- Normal acid–base status
Correct Answer: Metabolic alkalosis
Q8. A pharmacokinetic property of ethacrynic acid is that it is primarily eliminated by:
- Hepatic metabolism and biliary excretion
- Renal excretion unchanged only
- Expired air as volatile metabolites
- Sequestration in adipose tissue with very long half-life
Correct Answer: Hepatic metabolism and biliary excretion
Q9. Which lab parameter is most important to monitor soon after initiating ethacrynic acid therapy?
- Fasting blood glucose only
- Serum electrolytes (Na+, K+, Mg2+, Ca2+)
- Liver enzymes only
- Thyroid function tests
Correct Answer: Serum electrolytes (Na+, K+, Mg2+, Ca2+)
Q10. Ethacrynic acid is preferred over loop sulfonamides in patients with:
- Severe hepatic cirrhosis always
- History of sulfonamide allergy
- Gout as first choice therapy
- Pregnancy as safest diuretic
Correct Answer: History of sulfonamide allergy
Q11. Which adverse effect is especially associated with ethacrynic acid and other loop diuretics due to rapid intravascular volume depletion?
- Acute kidney injury (prerenal azotemia)
- Hypervolemia
- Weight gain due to fluid retention
- Increased intracranial pressure
Correct Answer: Acute kidney injury (prerenal azotemia)
Q12. Interaction of ethacrynic acid with NSAIDs typically results in:
- Enhanced diuretic effect due to increased renal blood flow
- Reduced diuretic efficacy due to inhibition of prostaglandin-mediated renal perfusion
- Complete inactivation of ethacrynic acid by NSAIDs
- No clinically significant interaction
Correct Answer: Reduced diuretic efficacy due to inhibition of prostaglandin-mediated renal perfusion
Q13. Which effect on serum uric acid is commonly seen with ethacrynic acid?
- Decrease in serum uric acid due to increased excretion
- Increase in serum uric acid due to decreased tubular secretion
- No change in uric acid levels
- Variable effect depending on sodium intake only
Correct Answer: Increase in serum uric acid due to decreased tubular secretion
Q14. When used IV for rapid diuresis, ethacrynic acid’s onset of action is typically:
- Within minutes (fast onset)
- Several days (delayed onset)
- Not effective IV
- Onset only after 24 hours
Correct Answer: Within minutes (fast onset)
Q15. Which patient condition is a relative contraindication to ethacrynic acid therapy?
- Severe hyponatremia or volume depletion without correction
- Compensated hypothyroidism
- Mild seasonal allergic rhinitis
- Stable controlled asthma
Correct Answer: Severe hyponatremia or volume depletion without correction
Q16. Which statement about ethacrynic acid’s chemical sensitivity is correct?
- It commonly causes sulfonamide-type allergic reactions
- It is used as an alternative in patients allergic to sulfonamide diuretics
- It contains a thiazide ring
- Its structure is identical to furosemide
Correct Answer: It is used as an alternative in patients allergic to sulfonamide diuretics
Q17. Combination of ethacrynic acid with aminoglycosides increases risk of:
- Hepatotoxicity
- Ototoxicity and potential permanent hearing loss
- Hypoglycemia
- Serotonin syndrome
Correct Answer: Ototoxicity and potential permanent hearing loss
Q18. A pharmacodynamic consequence of NKCC2 inhibition by ethacrynic acid is:
- Enhanced renal concentrating ability
- Impaired countercurrent multiplication leading to reduced medullary gradient
- Increased bicarbonate reabsorption in proximal tubule
- Direct stimulation of aldosterone secretion
Correct Answer: Impaired countercurrent multiplication leading to reduced medullary gradient
Q19. In overdose, one prominent acute risk with ethacrynic acid is:
- Severe hyperkalemia causing arrhythmia
- Profound diuresis with hypovolemia and electrolyte disturbances
- Immediate hepatocellular necrosis
- Central nervous system depression only
Correct Answer: Profound diuresis with hypovolemia and electrolyte disturbances
Q20. Which monitoring is particularly important when ethacrynic acid is used in combination with digoxin?
- Serum magnesium only
- Serum potassium to avoid digoxin toxicity due to hypokalemia
- Coagulation profile daily
- Thyroid function monthly
Correct Answer: Serum potassium to avoid digoxin toxicity due to hypokalemia
Q21. Ethacrynic acid’s effect on renal magnesium is:
- Decreased urinary magnesium excretion causing hypermagnesemia
- Increased urinary magnesium excretion causing hypomagnesemia
- No effect on magnesium balance
- Causes magnesium redistribution into cells only
Correct Answer: Increased urinary magnesium excretion causing hypomagnesemia
Q22. Which statement regarding pregnancy and ethacrynic acid is most appropriate?
- It is a safe first-line diuretic in pregnancy without restrictions
- Use cautiously; diuretics may reduce plasma volume and uteroplacental perfusion
- It is contraindicated in all trimesters due to teratogenicity proven in humans
- It is recommended to increase dose during pregnancy due to faster clearance
Correct Answer: Use cautiously; diuretics may reduce plasma volume and uteroplacental perfusion
Q23. Which formulation of ethacrynic acid is available for emergency intravenous use?
- Oral tablets only
- Intravenous (IV) formulation available
- Topical cream
- Inhalation aerosol
Correct Answer: Intravenous (IV) formulation available
Q24. The mechanism by which ethacrynic acid can precipitate gout involves:
- Increased urinary excretion of uric acid leading to low serum uric acid
- Decreased tubular secretion of uric acid leading to hyperuricemia
- Direct stimulation of uric acid synthesis in the liver
- Binding and inactivation of uricosuric transporters causing hypouricemia
Correct Answer: Decreased tubular secretion of uric acid leading to hyperuricemia
Q25. Which adverse dermatologic effect has been reported with ethacrynic acid?
- Photosensitivity reactions and rash
- Permanent hair loss in all patients
- Vitiligo as a universal side effect
- Complete resistance to skin infections
Correct Answer: Photosensitivity reactions and rash
Q26. Ethacrynic acid differs clinically from thiazide diuretics by producing which of the following:
- Greater natriuresis and diuresis with more potent reduction of edema
- Longer duration of action for chronic hypertension control
- Enhancement of distal NaCl reabsorption
- Primary potassium-sparing effect
Correct Answer: Greater natriuresis and diuresis with more potent reduction of edema
Q27. Which patient population requires dose adjustment or caution when using ethacrynic acid due to altered pharmacokinetics?
- Patients with severe hepatic impairment affecting drug metabolism and excretion
- Young healthy adults with normal liver and kidney function
- Patients using topical ophthalmic drops only
- Those with well-controlled hyperthyroidism only
Correct Answer: Patients with severe hepatic impairment affecting drug metabolism and excretion
Q28. In teaching mechanism to B.Pharm students, which explanation best describes ethacrynic acid’s inhibition at NKCC2?
- It irreversibly activates NKCC2 increasing salt reabsorption
- It blocks NKCC2, reducing reabsorption of Na+, K+, and Cl− and disrupting the medullary gradient
- It primarily blocks aquaporin channels to inhibit water reabsorption
- It increases aldosterone to enhance sodium retention
Correct Answer: It blocks NKCC2, reducing reabsorption of Na+, K+, and Cl− and disrupting the medullary gradient
Q29. Which monitoring parameter helps detect early ototoxicity during ethacrynic acid therapy?
- Serial audiometry and monitoring for tinnitus
- Daily liver function tests only
- Serum amylase only
- Chest X-ray weekly
Correct Answer: Serial audiometry and monitoring for tinnitus
Q30. For exam-style pharmacology question: Which adverse electrolyte triad commonly occurs with ethacrynic acid use?
- Hyperkalemia, hypermagnesemia, hypercalcemia
- Hypokalemia, hypomagnesemia, hypocalcemia due to increased excretion
- No electrolyte changes
- Isolated hypernatremia only
Correct Answer: Hypokalemia, hypomagnesemia, hypocalcemia due to increased excretion
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