KIDNEY DRUGS

Question 1

diuretic definition

Answer 1

substances that increase the rate of urine production

Question 2

brief way most diuretics work

Answer 2

increase the concentration of osmotically active agents n the urine, such as sodium or chloride ions

Question 3

two main types of diuretics + definition

Answer 3

osmotic diuretics- compounds filtered by the kidney which raise osmotic pressure of the urine, drawing water into them

natriuretics- increase the amount of sodium in the urine

Question 4

example of osmotic diuretic

Answer 4

mannitol

Question 5

how does mannitol work?

Answer 5

1. injected intravenously
2. freely filtered by kidney
3. raises osmolarity of filtrate, more water moves in

Question 6

main use of mannitol

Answer 6

treats life threatening oedema, particular cerebral

Question 7

examples of natriuretics

Answer 7

thiazide diuretics and loop diuretics

Question 8

when are loop diuretics used?

Answer 8

treatment of heart failure and hypertension

correct electrolyte disturbances, particularly hypercalcaemia

Question 9

most common example of a loop diuretic

Answer 9

furosemide

Question 10

action of furosemide

Answer 10

1. inhibits the NK2CC transporter in the thick ascending loop of Henle
2. less sodium and other ions able to be reabsorbed (remain in the lumen increasing osmolarity)
3. raised concentration detected by juxtaglomerular apparatus- triggers renin angiotensin mechanism- afferent arteriole dilates and efferent constricts
4. also due to increased ion concentration in lumen, more water moves in in the collecting duct
5. also as more ions remain in the lumen, less in the interstitium to pull water out of descending loop

Question 11

adverse affects of furosemide

Answer 11

hypokalaemia and loss of volume

Question 12

explain hypokalaemia

Answer 12

NK2CC channel blocked, so less potassium is moving from the lumen to the interstitium

1. increased sodium in distal tubule increases sodium movement through the basal sodium potassium pump
2. more sodium is being moved into the interstitium whereas potassium is being moved into the cell and then diffuses into the lumen
3. also more sodium in distal tubule activates JGA, leads to release of aldosterone
4. aldosterone increases sodium potassium ATPase, more potassium loss

Question 13

explain volume depletion

Answer 13

diuretics produce large amounts of urine, leading to a decrease in blood volume

Question 14

when are thiazides used?

Answer 14

treat heart failure and hypertension

Question 15

key example of thiazides

Answer 15

bendroflumethiazide

Question 16

mechanism of action of bendroflumethiazide

Answer 16

1. inhibits the action of NCC in distal convoluted tubule on apical surface of the epithelial cells
2. more sodium remains in the lumen, more water remains in the lumen

Question 17

comparison of thiazides with loop diuretics

Answer 17

less potent

smaller loss of potassium as does not interfere with NA/K pump

Question 18

two other types of diuretics

Answer 18

potassium sparing and carbonic anhydrase inhibition

Question 19

2 examples of potassium sparing diuretic

Answer 19

spironolactone and amiloride

Question 20

action of spiro

Answer 20

competitive antagonist of aldosterone

prevents more ENaC channels and sodium potassium ATPases forming in the collecting duct

less ions reabsorbed, less potassium moved in

Question 21

action of amiloride

Answer 21

inhibitor of the epithelial sodium channel in the collecting duct

inhibits sodium reabsorption and thus promotes water loss

Question 22

example of a carbonic anhydrase inhibitor

Answer 22

acetazolamide

Question 23

acetazolamide mechanism of action

Answer 23

acts in the proximal tubule

1. inhibits carbonic anhydrase
2. prevents the formation of carbonic acid and thus water and carbon dioxide
3. cannot diffuse into the epithelial cell, thus bicarbonate ions remain trapped in the lumen
4. increases excretion of bicarbonate ions alongside water, thus diuresis