Diuretics

Question 1

Thiazides: give example, site of action and mechanism.

Answer 1

Example – hydrochlorothiazide
Site of action – distal convoluted tubule
Mechanism – inhibition of NCC–> block Na+ and Cl- reabs (also increases ca++ reabs)

Question 2

Loop diuretic: give example, site of action and mechanism.

Answer 2

Example – furosemide
Site of action – Loop of Henle (TAL)
Mechanism – inhibition of NKCC–> block Na+, Cl- and K+ reabs

Question 3

Potassium sparing

- Sodium channel inhibitors: give example, site of action and mechanism.

Answer 3

Example – Triamterene, Amiloride
Site of action – cortical collecting tubule
Mechanism – inhibition of ENaC–> inhibit K+ secretion (inhibits Na+ reabs) and facilitates H+ secretion

Question 4

Potassium sparing- Aldosterone antagonists: give example, site of action and mechanism.

Answer 4

Example – Spironolactone
Site of action –cortical collecting tubule
Mechanism – inhibition of aldosterone receptor–> Repress the expression of EnaC and Na+/K+ ATPase

Question 5

Osmotic diuretic: give example, site of action and mechanism.

Answer 5

Example – Manitol
Site of action – proximal tubule and loop of Henle (DTL)
Mechanism – osmotic action

Question 6

Thiazides

Answer 6

Hydrochlorothiazide, Chlorthalidone, Bendroflumethiazide, Indapamide, Metolazone

Question 7

Loop diuretics

Answer 7

Sulfonamide derivatives: Furosemide, Bumetanide, Torsemide

Non-sulfonamide loop diuretic: Ethacrynic acid

Question 8

K+ Sparing-Na+ channel Inhibitors

Answer 8

Amiloride and Triamterene

Question 9

K+ Sparing-Aldosterone Antagonist

Answer 9

Spironolactone and Eplerenone.

Question 10

Carbonic Anhydrase Inhibitors. MOA?

Answer 10

Acetazolamide and Methazolamide
MOA: Inhibits carbonic anhydrase in apical membrane and cytoplasm of epithelial cells in the proximal convoluted tubules.• Block absorption of Na thru (Na/HCO3 exchanger)

Question 11

Osmotic diuretic

Answer 11

Mannitol

Question 12

What is a major SE of thiazide diuretics?

Answer 12

Hypokalemic metabolic alkalosis and hyperuricemia

Question 13

What are 2 major SE of Loop diuretics?

Answer 13

Hyperuricemia (gout) – d/t decreased excretion of uric acid

Hypomagnesaemia → osteoporosis

Question 14

What is a major SE of Triamterene (K+ sparing- Na+ channel inhibitor)?

Answer 14

Reduce glucose tolerance (careful w/ diabetics)

Question 15

What is a major SE of Spironolactone (Potassium sparing: Aldosterone Antagonist)?

Answer 15

Spironolactone may cause gynecomastia, impotence, hirsutism, irregular menses, and postmenopausal bleeding (less with Eplerenone).
B/C Spironolactone can bind to other sexual (steroid) receptors, blocking them.

Question 16

What is a major SE of mannitol (osmotic diuretics)?

Answer 16

Dehydration and hypernatremia d/t Excessive loss of more water relative to sodium.

Question 17

Sulfonamide derivative Loop diuretics are important and widely used in CV disturbances. What makes them unique?

Answer 17

They decrease total body fluid and increase amount in veins–> double effect in decreasing HTN