Question
Mechanism of action of loop diuretics.
Q6 3 marks Short Notes ★ ✓
Answer
Loop diuretics (Furosemide, Bumetanide, Torsemide) act on the thick ascending limb of the loop of Henle.
Mechanism
Inhibit the Na⁺-K⁺-2Cl⁻ (NKCC2) cotransporter on the luminal membrane of the thick ascending limb
This abolishes the countercurrent multiplier system and the medullary hypertonicity/concentration gradient, causing marked natriuresis and loss of urinary concentrating ability
Also increase excretion of K⁺, Ca²⁺, and Mg²⁺ (since reduced lumen-positive potential normally driving their reabsorption is lost)
Produce the most powerful diuresis of any diuretic class (“high-ceiling” diuretics), as up to 20-25% of filtered sodium is normally reabsorbed at this site
1 Renal Pharmacology
Other Years Asked
1 Compare the Mechanism of action, uses and adverse effects of Thiazides and Loop
diuretics. 2024 March (Supplementary) (2019 Scheme) Short Essay · 8 marks 2 Classify diuretic agents. Describe the mechanism of action, uses and adverse effects of
furosemide. (2+2+1+1=6) 2013 April (2010 Scheme) Essay · 6 marks 3 Enumerate three drug groups with two examples each for treating chronic simple glaucoma.
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1. It is a potassium sparing diuretic
2. It can cause gynecomastia and impotence
3. It acts on the thick ascending limb of Loop of Henle
4. It is combined with lisinopril to counteract hypokalemia 2024 December (Supplementary) (2019 Scheme) MCQ · 1 mark 21 Amiloride in lithium induced nephrogenic diabetes insipidus
Name the following (Two examples for each): (5x1=5) 2022 May (Supplementary) (2010 Scheme) Short Answer · 0.3 marks 22 Carbonic anhydrase inhibitors used to treat glaucoma 2024 March (Supplementary) (2019 Scheme) Short Answer · 0.2 marks 23 Carbonic anhydrase inhibitors 2022 February (2019 Scheme) Short Answer · 0.2 marks 24 Carbonic anhydrase inhibitors in glaucoma 2023 January (Supplementary) (2019 Scheme) Short Answer · 0.2 marks 25 Osmotic diuretics. 2024 June (Supplementary) (2019 Scheme) Short Answer · 0.2 marks 26 Aldosterone antagonist. 2023 July (Supplementary) (2019 Scheme) Short Answer · 0.2 marks 27 Uricosuric agents. 2023 July (Supplementary) (2019 Scheme) Short Answer · 0.2 marks 
