Pharmacology 2: Diuretics Use

Question 1

which part of the tubule do loop diuretics act on

Answer 1

loop of Henle

Question 2

how do loop diuretics work generally

Answer 2

blocks Na/K/2Cl into cells at apical membrane which does not concentrate the medulla and increases Na delivery to collecting tubule

Question 3

what effect do loop diuretics have on Na, K, Ca and Mg

Answer 3

they are all increased excretion

Question 4

what % of filtered Na is excreted via loop diuretics

Answer 4

15-25%

Question 5

why are loop diuretics beneficial in pulm oedema caused by HF

Answer 5

increased vasodilator effect

Question 6

what is Barter syndrome

Answer 6

autosomal recessive defect in K and Cl channel which mimics the effect of loop diuretics

Question 7

how are loop diuretics absorbed? what do they bind to? and how do they enter the nephron?

Answer 7

GI tract, plasma proteins, OAT secretion

Question 8

what are the main clinical indications for loop diuretics (4)

Answer 8

1) to reduce salt and water load eg pulm oedema, chronic HF, hepatic cirrhosis with ascites, nephrotic syndrome 2) increase urine volume in acute kidney failure 3) treat hypertension 4) hypercalcaemia

Question 9

name 2 loop diureitics

Answer 9

furosemide and bumetanide

Question 10

what are contraindications of loop diuretics

Answer 10

contraindications: severe hypovolaemia or dehydration

Question 11

what are cautions of loop diuretics (3)

Answer 11

1) severe hypokalaemia/ hyponatramia (esp digoxin, add potassium sparing diuretic) 2) gout 3) hepatic encephalopathy

Question 12

what are some adverse effects of loop diuretics (4)

Answer 12

1) hypovolaemia and hypotension (elderly), 2) hyperuriceaemia 3) hearing loss 4) hypo- kalaemia, calcaemia, magnesia

Question 13

where do thiazide diuretics act in the nephron

Answer 13

early distal tubule

Question 14

how do thiazide diuretics work generally

Answer 14

inhibits Na/Cl co transporter which increases Na delivery to collecting tubule

Question 15

what effect do thiazides have on Na, K, Ca and Mg

Answer 15

increased Na and K excretion, increased Ca reabsorption, no effect on Mg

Question 16

what % of filtered Na is excreted with thiazides

Answer 16

5%

Question 17

what additional action do thiazides have which make them useful in hypertension

Answer 17

vasodilators

Question 18

how are thiazide diuretics absorbed? how do they enter the nephron?

Answer 18

GI absorption, enter nephron via OATs

Question 19

what are clinical indications for thiazides (5)

Answer 19

mild HF, hypertension (indapamide), severe oedema, renal stones (reduced Ca excretion), diabetes insipidus

Question 20

name 3 thiazides

Answer 20

bendroflumethiazide, chlortalidone, indapamide

Question 21

what is a contraindication of thiazides

Answer 21

hypokalamia

Question 22

what are 2 cautions of thiazides

Answer 22

hyponatraemia, gout

Question 23

what are some side effects of thiazides (7)

Answer 23

hypokalaemia, met alkalosis, hyovolaemia/ hypotension, hypomagensia, hyperuricaemia, erectile dysfunction, impaired glucose tolerance (diabetics)

Question 24

how do loop and thiazides cause potassium loss (3)

Answer 24

1) increased Na load causes enhanced reabsoprtion in collecting tubules 2) more negative lumen 3) increased driving force causes K secretion and excretion

Question 25

where do potassium sparing diuretics act

Answer 25

collecting ducts

Question 26

how do potassium sparing diuretics work generally

Answer 26

blocks apical membrane sodium channel which decreases reabsorption and as no charge change K is not excreted

Question 27

how are potassium sparing diuretics absorbed? how do they enter the nephron?

Answer 27

triamterene well absorbed from GI (not amiloride), enters nephrons via OCTs

Question 28

name 2 potassium sparing diuretics

Answer 28

amiloride and triamterene

Question 29

how do aldosterone antagonists work

Answer 29

compete with aldosterone to decrease RAAS system to then decrease Na reabsorption (and K excretion)

Question 30

name 2 aldosterone antagonists

Answer 30

spironolactone and eplerenone

Question 31

what are clinical indications for potassium sparing diuretics

Answer 31

usually with other diuretics to prevent hypokalaemia (alone they cause hyperkalaemia)

Question 32

what are clinical indications for aldosterone antagonists (4)

Answer 32

HF, primary hyperaldosteronism (Conn’s), resistant hypertension, secondary hyperaldosteronism

Question 33

what are contraindications for potassium sparing diuretics and aldosterone antagonists (3)

Answer 33

severe renal impairment, hyperkalaemia, Addison’s