Diuretics

Question 1

what will diuretics do

Answer 1

increase volume of urine
change pH of urine
change ionic composition (Na, Cl, K, HCO) of urine and blood

Question 2

name diuretic agents

Answer 2

carbonic acid anhydrase inhibitors 
loop diuretics 
thiazides 
potassium sparing diuretics 
osmotic diuretics 
anti diuretic hormone antagonists

Question 3

mode of action of carbonic anhydrase inhibitors

Answer 3

inhibit the enzyme carbonic anhydrase in the proximal tubular epithelial cells
Carbonic anhydrase (CAse) is an enzyme which catalyses the reversible reaction H2O + CO2 H2CO3, which spontaneously ionizes into H+ + HCO3
Only mild diuresis action
The enzyme is present in renal tubular cell (especially PT) gastric mucosa, exocrine pancreas, ciliary body of eye, brain and RBC

Question 4

therapeutic uses of carbonic anhydrase inhibitors

Answer 4

treatment of glaucoma
epilepsy
mountain sickness

Question 5

side effects of carbonic acid anhydrase inhibitors

Answer 5

metabolic acidosis 
metabolic alkalosis 
hypokalemia 
renal stone formation 
drowsiness 
abnormal taste
decreased libido
lethargy

Question 6

mode of action for loop diuretics

Answer 6

inhibits Na, K, Cl cotransport on ascending loop of Henle, decreasing reabsorption

Question 7

therapeutic uses of loop diuretics

Answer 7

pulmonary edema

hypertension

Question 8

side effects of loop diuretics

Answer 8

hypokalemic metabolic alkalosis 
hyperuricemia 
ototoxicity 
acute hypovolemia 
hypokalemia

Question 9

contraindications of loop diuretics

Answer 9

hypersensitivity to sulphonamides
hepatic coma
renal failure
hypokalemia

Question 10

mode of action of thiazides

Answer 10

inhibitors of Na Cl symport

site of action usually at descending limb of loop of henle and dct

Question 11

therapeutic uses of thiazides

Answer 11

hypertension 
CHF (heart failure) 
hypercalciuria 
nephrogenic
diabetes insipidus

Question 12

side effects related to diuretic effect of thiazides

Answer 12

hypokalemia
metabolic alkalosis
hyponatremia 
hypovolemia 
hypotension
hypomagnesia
hypercalcemia

Question 13

side effects not related to diuretic effect of thiazides

Answer 13

hyperuricemia
hyperglycaemia
hyperlipidaemia
impotence (erectile dysfunction)

Question 14

interactions of thiazides

Answer 14

cardiac glycosides 
antidiabetic agents
lithium
uricosuric agents
NSAIDS
potassium depleting agents

Question 15

contraindications of thiazides

Answer 15

severe renal / hepatic impairment
hypokalaemia
pre existing hypercalcaemia
hypersensitivity to thiazides

Question 16

osmotic diuretics (manitol) mode of action

Answer 16

reduce water reabsorption which results in reduction of sodium reabsorption

Question 17

potassium sparing diuretics (spironolactone)

Answer 17

Competitively bind to aldosterone receptors in the late distal convoluted tubule → inhibition of aldosterone effects

Question 18

interactions of furosemide

Answer 18

Aminoglycosides + furosemide - ↑ ototoxicity
Cephalosporines + furosemide - ↑ renal failure
Sulfonamides + furosemide – cross-hypersensitity
Plasma protein binding displaced by warfarin

Question 19

potassium sparing diuretics (epithelial sodium channel blockers)

Answer 19

Direct inhibition of ENaCs in distal convoluted tubules and collecting ducts