Diuretics

Question 1

Draw out diuretics sites of action on the nephron

Answer 1

page 604

Question 2

Acetazolamide

Answer 2

carbonic anhydrase inhibitor
proximal convoluted tubule -> HCO3- excretion
mild diuretic

use:
altitude sickness
alkalinize urine
metabolic alkalosis

glaucoma* ->decreased virtuous humor production

idiopathic intracranial htn - pseudotumor cerebri

SE: metabolic acidosis, sulfa allergy

Question 3

Mannitol

Answer 3

proximal tubule

osmotic diuretic - prevents reabsorption of water -> excretion of free water

increased serum osmolarity
increased serum Na+

SE: dehydration
Contra: anuric renal failure, CHF

use: shock, drug OD, *acute angle closure glaucoma
elevated ICP

Question 4

Loop diuretics

Answer 4

Most potent
Sulfas:
Bumetanide
Furosemide - MC
Torsemide

Non-sulfa: ethacrynic acid

thick ascending limb - inhibits Na/K/2Cl
-can’t concentration interstitium -> decreased H2O absorption in thin descending limb -> dilute urine

increased ca2+ secretion

Use:
severe edema: CHF, pulmonary edema, nephrotic sn, cirrhosis

SE:
hypokalemia
dehydration
gout
sulfa allergy - except ethacrynic acid

taken w/ amino glycoside or vancomycin: ototoxicity, nephrotoxicity

Question 5

Thiazide diuretics

Answer 5

DCT

2nd Most potent

Chlorthalidone
Hydrochlorothiazide MC
metolazone

inhibit Na/Cl absorption in distal convoluted tubule -> high electrolyte fluid in urine

retain Ca2+ - deceased Ca2+ excretion

Tx:
HTN
CHF or edematous dz
idiopathic hypercalciuria
nephrogenic DI

SE:
hypokalemia
hyponatremia

hyperglycemia
hyperlipidemia
hyperuricemia
hypercalemia

avoid w/ sulfa allergies

Question 6

Potassium sparing diuretics

Answer 6

CT

“taKe a SEAT”

Aldosterone antagonists:
Spironolactone
Eplerenone

Inhibit epithelial Na+ channels:
Amiloride
Triamterene

Tx hyperaldosteronism
Triamterene w/ loop or thiazide diuretic to tx CHF w/ hypokalemia

SE:
hyperkalemia -> arrhythmias - VT, Vfib
Spironolactone:
antagonize androgen receptors -> gynecomastia
anti androgen effects -> acne, PCOS
Progesterone agonist: menstrual irregularities

Question 7

CHF treatment to improve survival, decrease mortality

Answer 7

b-blocker
ACEI/ARB
Alosterone antagonist

Question 8

Blood chemistry changes w/ diuretics

Answer 8

increased urinary NaCl - except acetazolamide
Increased urinary K+ - except K+ sparing
Acidosis - carbonic anhydrase I; K+ sparing
Alkalosis - loops and thiazides