Pharm Block II - Diuretics

Question 1

diuretic drugs that work on the proximal tubule

Answer 1

carbonic anhydrase inhibitors, mannitol

Question 2

diuretic drugs that work on the loop of Henle

Answer 2

loop diuretics (ascending limb); osmotic diuretics (descending limb)

Question 3

diuretic drugs that work on the distal convoluted tubule

Answer 3

thiazide diuretics, K+ sparing diuretics

Question 4

Loop diuretics examples

Answer 4

Furosemide, ethacrynic acid

Question 5

Loop diuretics MOA

Answer 5

Inhibit sodium and chloride reabsorption in ascending limb of loop of Henle; increase renal prostaglandins resulting in dilation of blood vessels and reduced peripheral vascular resistance

Question 6

Loop diuretics indications

Answer 6

Edema associated with heart failure or hepatic/renal disease, HTN (if related to volume)

Question 7

Loop diuretics adverse effects

Answer 7

Hypokalemia, hyperglycemia, hyperuricemia, ototoxicity

Question 8

Thiazides examples

Answer 8

Hydrochlorothiazide, chlorthalidone, metolazone

Question 9

Thiazides MOA

Answer 9

Inhibits tubular reabsorption (in distal tubule and ascending loop of Henle) of sodium and chloride (so water, sodium and chloride are excreted); also dilates arterioles

Question 10

Thiazides indications

Answer 10

HTN (due to diuretic and vasodilation effects), edematous states, CHF, hypercalciuria

Question 11

Thiazides adverse effects

Answer 11

Dizziness, headache, blurry vision, anorexia

Question 12

Potassium sparing diuretics example

Answer 12

Spironolactone

Question 13

Spironolactone MOA

Answer 13

Interfere with sodium/potassium exchange, competively bind to aldosterone receptors, block reabsorption of sodium/water

Question 14

Spironolactone indications

Answer 14

Hyperaldosteronism, ascites, CHF

Question 15

Spironolactone adverse effects

Answer 15

Hyperkalemia, nausea, gnecomastia, lethargy, mental confusion

Question 16

volume depletion from diuretic therapy

Answer 16

where Na goes, water follows. causes reduced BP, pulmonary & systemic vascular resistance, reduced central venous pressure, and reduced L ventricular end diastolic pressure

Question 17

azotemia from diuretic therapy

Answer 17

increase in BUN and SCr due to decrease in renal perfusion & decreased GFR

Question 18

hypokalemia from diuretic therapy

Answer 18

2 mechs cause this:1. high tubular flow to the cortical collecting ducts, increase delivery of Na to the collective duct & decrease in intravasc vol as a result of salt wasting. 2. diuretics stimulate aldosterone, so low intravasc vol resulting in hyperaldosteronism & enhanced secretion of aldosterone

Question 19

hyperkalemia from diuretic therapy

Answer 19

K sparing diuretics reduce both K & H secretion in the collecting tubules

Question 20

hyperuricemia due to diuretic therapy

Answer 20

reduced urate secretion due to competition for organic acid secreting pathway. increase renal reabsorption secondary to plasma vol contraction

Question 21

hyponatremia due to diuretic therapy

Answer 21

almost all cases are due to thiazides (not loop diuretics), the ECF vol depletion stimulates ADH, causing impaired water excretion, resulting in hyponatremia

Question 22

hyperglycemia due to diuretic therapy

Answer 22

exact mech is unknown - possibly due to decreased insulin secretion, decreased tissue sensitivity to insulin or increased insulin depletion. loop diuretics have less marked effect than thiazides

Question 23

hypomagnesemia due to diuretic therapy

Answer 23

approx 70% of the filtered Mg is reabsorbed in the thick ascending limn and 10% in the distal convoluted tubule. inhibition of Na/K/Cl transporter by loop diuretics diminishes the lumen to positive potential required to reabsorb Mg

Question 24

Diuretic resistance

Answer 24

Process of eliminating excess sodium and water stops before enough fluid has been removed

Question 25

How to manage diuretic resistance

Answer 25

Switching to another diuretic class; infuse loop diuretics continuously; ultrafiltration using hemodialysis