Order the following diuretics from the beginning of the nephron to the end based on where they exert their mechanism of action.
Answer with Rationale
One of the formats available for question options on the exam are what is called "Ordered-Response" where you have to place the given choices in a particular order depending on the question. This could be "highest to lowest", "smallest to largest", etc. and so careful attention to wording is required to appropriately answer the question. The correct order for this question would be C-A-D-B. Acetazolamide works in the proximal convoluted tubule so would be first. Next would be furosemide which of course works in the thick ascending limb or "loop" of Henle. Third would be chlorthalidone, a thiazide diuretic which exerts its effect in the distal convoluted tubule. Finally, spironolactone, a potassium-sparing diuretic (also an aldosterone antagonist) works at the end of the nephron in the collecting ducts. Hence by the time you get to the end of the nephron, the water loss potential with these agents is limited compared to loop diuretics which decrease reabsorption of significant volume within the loop of Henle. This is why loops are the diuretic class used primarily for heart failure management when patients require volume removal.
For more reading on diuretic mechanism of action, check out this resource on AccessPharmacy:
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