Lasix acts on the:

Appeared in: AIIMS Delhi NO-2016

Explanation

Lasix (Furosemide) is classified as a loop diuretic, which provides a direct clue to its site of action.
It primarily acts on the thick ascending limb of the Loop of Henle.
The mechanism involves inhibiting the Na-K-2Cl cotransporter, which prevents the reabsorption of these electrolytes.
This inhibition leads to a powerful diuretic effect, as water follows the retained electrolytes in the tubule.

Option B: The proximal convoluted tubule is the site of action for other classes of diuretics, primarily carbonic anhydrase inhibitors and osmotic diuretics, not loop diuretics.
Option C: The distal convoluted tubule is the primary site of action for thiazide diuretics, such as hydrochlorothiazide.
Option D: The collecting duct is the target for potassium-sparing diuretics, which have a different mechanism and site of action than loop diuretics.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pharmacology: Site of action of loop diuretics as background academic context rather than a clinical decision trigger.
Lasix is a cornerstone in managing fluid overload in conditions like heart failure, liver cirrhosis, and renal disease. Nurses frequently administer this medication and must monitor its effects.
Key nursing interventions include monitoring vital signs (especially blood pressure), intake and output, daily weights, and serum electrolytes (particularly potassium, as Lasix can cause significant hypokalemia).
Nurses should also assess for signs of dehydration (e.g., poor skin turgor, dry mucous membranes) and ototoxicity (hearing loss, tinnitus), a rare but serious side effect, especially with high doses or rapid IV administration.

How to Approach the Question

First, identify the drug mentioned in the question: 'Lasix'.
Recall the generic name and drug class. Lasix is the brand name for Furosemide, which is a 'loop diuretic'.
The name of the class, 'loop diuretic', directly points to its primary site of action in the kidney.
Associate the drug class with its specific location in the nephron. Loop diuretics act on the Loop of Henle.
Scan the options provided and select the one that matches your knowledge. In this case, 'Loop of Henle' is the correct choice.

Concept Tested & Keywords

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E6 Pharmacology KD Tripathi Essentials 9e Part 2 p. 252-254

E6 Pharmacology Katzung 16e p. 423-425

E6 Pharmacology Nursing Lilley 11e Part 2 p. 148-150

Practise the full AIIMS Delhi NO-2016

Attempt every question from this paper in a timed mock, then review the full solution for each one.