Diuretics

Question 1

What are the 4 main types of diuretics?

Answer 1

1. Osmotic diuretics / carbonic anhydrase inhibitors
2. Loop diuretics
3. Thiazide / thiazide like diuretics
4. Potassium sparing diuretic

Question 2

How does the filtrate pass from the PCT to the DCT?

Answer 2

Loop of Henle

Question 3

Where do the osmotic / CAI diuretics act?

Answer 3

PCT

Question 4

Where do the loop directives act?

Answer 4

Ascending limb if the Loop of Henle

Question 5

Where do the thiazide diuretics act?

Answer 5

DCT

Question 6

Where do the potassium-sparing diuretics act?

Answer 6

Late DCT and early collecting duct

Question 7

Give an example of an osmotic diuretic.

Answer 7

Mannitol

Question 8

What can cause an osmotic diuretic effect in uncontrolled diabetes?

Answer 8

The hyperglycaemia

Question 9

What do osmotic diuretics do?

Answer 9

Inhibit water reabsorption in the PCT and early loop of Henle and retains water in the tubular lumen

Question 10

When is mannitol given ?

Answer 10

When there is raised intracranial pressure and intraocular pressure

Question 11

What are the side-effects of mannitol?

Answer 11

Hypotension
Fluid and electrolyte disturbance

(NOTE UNCOMMON)

Question 12

Give an example of a carbonic anhydrase inhibitor.

Answer 12

Acetazolamide

Question 13

What does acetazolamide do?

Answer 13

Reduced Na+ and HCO3- reabsorption and it is a weak diuretic as its action is partially compensated by great Na+ reabsorption in DCT

Question 14

When prescribes in glaucoma, what does acetazolamide do?

Answer 14

It locally acts to inactivated carbonic anhydrase and interfere with the Na+ pump, which will decrease tumour formation and therefore lower intraocular pressure

Question 15

What are the adverse effects of acetazolamide?

Answer 15

• metabolic acidosis
• hypokalaemia
• renal stone formation

Question 16

What would acetazolamide do to the body at high altitudes ?

Answer 16

Help with altitude sickness -
Prevent biacarbonate uptake in the kidney and help to correct the alkalosis, causing a mild metabolic acidosis causing an increase in respiratory rate to offload CO2 in the breath and improve O2 uptake

Question 17

Give 3 examples of loop diuretics

Answer 17

Furosemide
Bumetanide
Torasemide

Question 18

How do loop diuretics enter the lumen of the PCT?

Answer 18

They are secreted into the tubular lumen by PCT cells via organic anion transporters (OAT)

Question 19

What will furosemide do once it has entered the tubular lumen ?

Answer 19

Inhibit a region imperative to water caked the Na+/K+/2Cl- co-transporter in ascending limb of loop of Henle

Question 20

Aside from reducing the reabsorption kg water from the collecting duct, what can furosemide do?

Answer 20

Increase renal prostaglandin production which produces vasodilation, increasing renal blood flow and assisting diuresis

Question 21

What are the electrolytes in which there is an increase in their secretion with use of furosemide ?

Answer 21

Ca2+ and Mg2+ due to inhibition of paracellular diffusion

Question 22

What do loop diuretics do to the potential difference across the tubule cell and what generates this?

Answer 22

Decreases it

Recycling of K+

Question 23

What are loop diuretics good for the treatment of?

Answer 23

• congestive heart failure
• resistant hypertension
• liver ascites
• nephrotic syndrome
• acute hypercalcaemia

Question 24

Why would the loop diuretic not be prescribed for a patient as monotherapy for hypertension ?

Answer 24

Offloading a large amount of fluid would lead to activation of the RAAS system which would in turn, increase Bp

Question 25

What is the preferred route for acute relief of symptoms ?

Answer 25

IV

Question 26

What are the adverse effects of loop diuretics ?

Answer 26

• hypvolaemia and dehydration
• hypokalaemia (cramps and arrhythmias)
• hypomagnesaemia
• hypoatraemia
• hyperueicaemia (gout)
• too and renal toxicity
• allergic reactions

Question 27

If the loop diuretic is given along side a thiazide diuretic, what would the risk be?

Answer 27

There would be an increase risk of electrolyte disturbance

Question 28

There is increased oto and nephrotoxicitybwhen when a loop diuretic is combined with_________?

Answer 28

Aminoglycoside antibiotics

Question 29

What other drug in conjunction with a loop diuretic would increase the risk of hypotension ?

Answer 29

Vasodilator drugs