Review Question - QID 213785

This patient with congestive heart failure who is developing gynecomastia most likely is suffering from the side effects of spironolactone, which acts upon the collecting duct of nephron.

Spironolactone is a diuretic that function as competitive aldosterone receptor antagonists. They act on the collecting duct of the nephron to reduce sodium reabsorption by decreasing activity of the epithelial sodium channel (ENAC). Since sodium reabsorption is accompanied by potassium secretion in this region of the nephron, these drugs will function as potassium-sparing diuretics. They can be used to treat congestive heart failure as well as female hirsutism. Important side effects include hyperkalemia and gynecomastia.

Incorrect Answers:
Answer 2: Distal convoluted tubule is the site of action for thiazide diuretics that can also be used in hypertension and congestive heart failure; however, the major side effects of these drugs are hypercalcemia, hyperlipidemia, and hyperuricemia.

Answer 3: Glomerular arterioles are the site of action for angiotensin receptor blocker drugs; however, the major side effects of these drugs are decreased glomerular filtration rate and hyperkalemia.

Answer 4: Loop of Henle is the site of action for loop diuretics such as furosemide, which can be used in patients with acutely decompensated congestive heart failure; however, the major side effects of these drugs are ototoxicity and interstitial nephritis.

Answer 5: Proximal convoluted tubule is the site of action for osmotic diuretics such as mannitol as well as acetazolamide. The side effects of acetazolamide include neuropathy, renal stone production, and ammonia toxicity.

Bullet Summary:
Spironolactone is a competitive aldosterone receptor antagonist that acts on the collecting duct of the nephron.