Diuretics Flashcards
Why are carbonic anhydrase inhibitors such weak diuretics?
Because they act on the proximal, so there’s PLENTY of nephronal sections to compensate for the loss.
Why does acetazolamide cause metabolic acidosis?
Normally carbonic anhydrase (in the nephron cell) provides HCO3- back to the blood to keep it alkaline.
What transporter in the thick ascending loop of Henle does frusemide inhibit?
Na/K/2Cl symporter
How long is the onset of a loop diuretic?
30-60 minutes, quite rapid.
How long is the duration of loop diuretics?
4-6 hours, quite brief.
What other puzzling effect do loop diuretics have before the onset of diuresis?
Vasodilation.
Why would frusemide cause hypokalaemia?
By sending Na+ rich tubular fluid to the collecting tubules, where they are exchanged for K+, which is lost to the urine.
Does Cl- make the blood more acidic?
Yes.
Why would loop diuretics cause metabolic alkalosis?
By reducing Cl- reabsorption.
Is the activity of loop diuretics dependent on glumerular filtration rate?
No. So THEY ARE GOOD FOR PATIENTS WITH RENAL FAILURE.
What’s a normal amount of urine to produce on a typical day?
How much do you see with loop diuretic treatments?
1.5L
4L for loop diuretics.
What two things do thiazides do for hypertension?
- BP drop due to fluid loss.
2. vasodilation (mechanism not important).
Loop diuretics and thiazides don’t have much to do with carbonate or anything. How do they cause metabolic alkalosis?
They reduce Cl- reabsorption.
Cl- increases pH.
Bonus: recall that for some reason Na+ also exchanges for H+ in the collecting tubule.
We diuretic ourselves into dehydration (unless we really really try) because of ..
.. DIURETIC BRAKING. Our body’s multiple homeostatic mechanisms put a ceiling on diuresis.
What drug interactions are particularly risky with hypokalaemia?
Ionotropic drugs like dixogin or class III antiarrhythmics.
