Diuretics

Question 1

give an example of an osmotic diuretic

Answer 1

mannitol

Question 1

explain the action of an osmotic diuretic

Answer 1

Filtered by the glomerulus but not readily reabsorbed, this increases the osmolarity of urine in the tubules, reducing the amount of water reabsorption

Question 2

what are the uses of osmotic diuretics?

Answer 2

remove fluid from tissues / organs e.g. acute glaucoma / eye surgery (reduce pressure), cerebral oedema following injury or trauma or neurosurgery (reduce brain swelling), also in oliguria (lower than normal urine production) e.g. renal failure

Question 3

where are osmotic diuretics not used and why?

Answer 3

heart failure because mannitol increase blood osmolarity and therefore increases the fluid uptaken from tissues, which can further increase blood pressure, although more fluid is being removed from the body it is distributed differently meaning blood volume is not effectively decreased

Question 4

give an example of a loop diuretic?

Answer 4

furosemide

Question 5

explain the action of furosemide

Answer 5

inhibits the NKCC2 transporter in the ascending limb of the loop of Henle
decreases osmolarity of the medullary interstitial space, reduces water reabsorption

Question 6

what are the side effects of loop diuretics?

Answer 6

dehydration
* Increase in Mg, Ca, H, and K excretion, leading to deficiencies such as hypokalaemia which can effect cardiac health
* The loss of H+ can result in alkalosis
deafness (ototoxicity), this is likely due to disturbances of the electrolyte balance in the fluid in the ear (common in young children)

Question 7

what are the therapeutic used of loop diuretics?

Answer 7

• Heart failure, pulmonary oedema, renal failure, hypertension, drug overdose
  Hypercalcemia/kalaemia

Question 8

where do thiazide and thiazide like drugs act?

Answer 8

DCT

Question 9

how strong are thiazide diuretics?

Answer 9

Only 5-10% of Na+ is reabsorbed in the DCT so they are less strong than loop diuretics

Question 10

what are the side effects of thiazide diuretics?

Answer 10

increase K, Mg and H excretion and Ca

Question 11

what can thiazide diuretics be used to treat?

Answer 11

hypertension, oedema, heart failure, kidney stones (as they’re related to high levels of calcium)

Question 12

give an example of a potassium sparing diuretics

Answer 12

spironolactone, Amiloride/ triamterene,

Question 13

what are the side effects of spironolactone?

Answer 13

hyperkalaemia (due to K+ sparing), also it may act on other steroid receptors causing sexual dysfunction and gynaecomastia (breast growth e.g. in males)