Diuretics Flashcards
(29 cards)
What are the 4 main types of diuretics?
- Osmotic diuretics / carbonic anhydrase inhibitors
- Loop diuretics
- Thiazide / thiazide like diuretics
- Potassium sparing diuretic
How does the filtrate pass from the PCT to the DCT?
Loop of Henle
Where do the osmotic / CAI diuretics act?
PCT
Where do the loop directives act?
Ascending limb if the Loop of Henle
Where do the thiazide diuretics act?
DCT
Where do the potassium-sparing diuretics act?
Late DCT and early collecting duct
Give an example of an osmotic diuretic.
Mannitol
What can cause an osmotic diuretic effect in uncontrolled diabetes?
The hyperglycaemia
What do osmotic diuretics do?
Inhibit water reabsorption in the PCT and early loop of Henle and retains water in the tubular lumen
When is mannitol given ?
When there is raised intracranial pressure and intraocular pressure
What are the side-effects of mannitol?
Hypotension
Fluid and electrolyte disturbance
(NOTE UNCOMMON)
Give an example of a carbonic anhydrase inhibitor.
Acetazolamide
What does acetazolamide do?
Reduced Na+ and HCO3- reabsorption and it is a weak diuretic as its action is partially compensated by great Na+ reabsorption in DCT
When prescribes in glaucoma, what does acetazolamide do?
It locally acts to inactivated carbonic anhydrase and interfere with the Na+ pump, which will decrease tumour formation and therefore lower intraocular pressure
What are the adverse effects of acetazolamide?
- metabolic acidosis
- hypokalaemia
- renal stone formation
What would acetazolamide do to the body at high altitudes ?
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
Give 3 examples of loop diuretics
Furosemide
Bumetanide
Torasemide
How do loop diuretics enter the lumen of the PCT?
They are secreted into the tubular lumen by PCT cells via organic anion transporters (OAT)
What will furosemide do once it has entered the tubular lumen ?
Inhibit a region imperative to water caked the Na+/K+/2Cl- co-transporter in ascending limb of loop of Henle
Aside from reducing the reabsorption kg water from the collecting duct, what can furosemide do?
Increase renal prostaglandin production which produces vasodilation, increasing renal blood flow and assisting diuresis
What are the electrolytes in which there is an increase in their secretion with use of furosemide ?
Ca2+ and Mg2+ due to inhibition of paracellular diffusion
What do loop diuretics do to the potential difference across the tubule cell and what generates this?
Decreases it
Recycling of K+
What are loop diuretics good for the treatment of?
- congestive heart failure
- resistant hypertension
- liver ascites
- nephrotic syndrome
- acute hypercalcaemia
Why would the loop diuretic not be prescribed for a patient as monotherapy for hypertension ?
Offloading a large amount of fluid would lead to activation of the RAAS system which would in turn, increase Bp
