Pharmacology: Osmotic Diuretics and Carbonic anhydrase inhibitors

Question 1

give an example of an osmotic diuretic

Answer 1

mannitol

Question 2

describe the action of osmotic diuretics

Answer 2

they increase the osmolality of the filtrate, which opposes the absorption of water in parts of the nephron that are freely permeable to water

Question 3

what is the major site of action of osmotic diuretics in the kidney

Answer 3

the proximal tubule where most iso-osmotic reabsorption of water occurs

Question 4

what secondary action do osmotic diuretics have on sodium rebasorption

Answer 4

they decrease Na reabsorption

Question 5

when are osmotic diuretics used

Answer 5

in prevention of acute hypovolaemic renal failure to maintain urine flow, or in urgent treatment of raised IOP or ICP

Question 6

what are the adverse effects of osmotic diuretics

Answer 6

transient expansion of blood volume ad hyponatraemia

Question 7

give an example of a carbonic anhydrase inhibitor

Answer 7

acetazolamide

Question 8

describe the action of carbonic anhydrase inhibitors

Answer 8

increase excretion of HCO3 with Na, K and water

alkaline diuresis and metabolic acidosis as result

Question 9

when are carbonic anhydrase inhibitors used

Answer 9

glaucoma, prophylaxis of altitude sickness, some forms of infantile epilepsy