Loop diuretics - Objectives Flashcards
How do diuretics reach their site of action?
Most other diuretics are tightly protein bound and undergo little filtration. They reach the urine via secretion across the proximal tubule (organic acid or base secretory pathway).
Exceptions = spironolactone, eplerenone, and ADH antagonists. Mannitol is filtered at glomerulus
Why does acetazolamide produce an alkaline urine (pH = 8.2)?
CA inhibitor, blocking the reabsorption of HCO3- (a base).
Why do thiazide and loop diuretics cause potassium loss?
Thiazide: blocks NaCl cotransport, halting Na/K ATPase
Loop: blocks NKCC cotransport
How do thiazide and loop diuretics affect calcium excretion?
Thiazide diuretics decrease Ca2+ excretion
Loop diuretics increase Ca2+ excretion
How do carbonic anhydrase inhibitors cause a diuresis?
Na+ accompanies HCO3-, which is stuck within the tubule
Which class of diuretics would cause increased excretion of magnesium?
Loop diuretics
MOA of amiloride?
Blocks Na+ channels in collecting tubule, reducing H+ and K+ secretion into the urine
What class of diuretics interferes with sodium reabsorption in the proximal tubule?
Acetazolamide and friends
How would the combination of a loop diuretic and thiazide diuretic influence sodium excretion?
Dramatically increase sodium excretion
What are the effects of spironolactone on urinary potassium excretion?
K+ sparing agent
What is the most common reason for diuretic use?
Reducing edema by reducing ECV
Which diuretic drugs would be indicated to reduce edema/ascites in patients with hepatic cirrhosis?
Spironolactone/eplerenone
Which thiazide-like diuretic is most likely to be efficacious in patients with severe renal insufficiency?
Metolazone
