Diuretics

Question 1

Mannitol

Answer 1

Increase nephron osmolarity in proximal tubule and thin descending loop of Henle (osmotic diuretic)
Uses: decrease intracranial/intraocular pressure, drug overdose
Toxicity: pulmonary edema, dehydration
Freely filtered through glomerulus, excreted unchanged in 30-60 mins

Question 2

Acetazolamide

Answer 2

Inhibitor of carbonic anhydrase in the proximal convoluted tubule (do not reabsorb bicarb)
Uses: glaucoma, metabolic alkalosis, acute mountain sickness
Toxicity: hyperchloremic metabolic acidosis, paresthesias, sulfa allergy
Results in urine alkalinization, metabolic acidosis, and hyperchloremia

Question 3

Furosemide

Answer 3

Inhibits NKCC2 in thick ascending limb of Henle
Uses: edema (due to CHF, cirrhosis, nephrotic syndrome), hypertension, hypercalcemia
Toxicity: hypokalemia, ototoxicity, dehydration
“High ceiling” diuretic, rapid onset on action

Question 4

Hydrochlorothiazide

Answer 4

Inhibits NCC co-transporter in distal convoluted tubule
Uses: hypertension, congestive heart failure, idiopathic hypercalciuria
Toxicity: hypokalemic metabolic alkalosis, hyponatremia, hyperlipidemia, hyperuricemia, hypercalcemia
“Low ceiling” diuretic, component of many combination therapies

Question 5

Amiloride

Answer 5

Inhibits ENaC in cortical collecting duct
Uses: congestive heart failure, hypertension, hypokalemia
Toxicity: hyperkalemia
K-sparing diuretic, used in combination with loop and thiazide diuretics

Question 6

Spironolactone

Answer 6

Competitive antagonist of aldosterone receptor
Uses: hyperaldosteronism, congestive heart failure, hypertension
Toxicity: hyperkalemia, endocrine effects (gynecomastia)
Used in combination with loop or thiazides to prevent hypokalemia, eplerenone lacks anti-androgen effects

Question 7

Tolvaptan

Answer 7

V2 vasopressin receptor antagonist (decreased aquaporin insertion and increased H2O excretion)
Uses: SIADH, hyponatremia
Toxicity: nephrogenic diabetes insipidus, hepatotoxicity