REN drugs Flashcards
What drug blocks hydrogencarbonate absoption
Acetazolamide
Where in the kidneys does Acetazolamide target
Acts mainly in the proximal tubule
How does acetazolamide work
Blocks carbonic anhydrase
Can acetazolamide be used a direuetic
Yes, it is a weak one
acts in later parts of tubule, and can retain the bicarbonate
What are the uses of acetazolamide
glaucoma, mountain sickness prophylaxis
Why do we use acetazolamide for altitude sickness
-the drug can cause metabolic acidosis
-because when we are at altitude
-we get respiratory alkalosis because the partial pressure of o2, is lower
-so we ventilate more
-in doing so we lose co2.
-Anyways we give this before you climb a mountain because this causes acidosis
-which will counteract with alkalosis caused by high altitude
What is a problem with acetazolamide
The pH of urine will become alkaline → leading to metabolic acidosis
Does caffine have a diuretic effect
Yes
How does caffine have a diuretic effect
it works on the adenosine recpetor
so if increase GFR, we inhibit sodium ion reabsoption, so we get a diuresis
Name a widely used potent diuretic
Furosemide
How does furosemide work
Acts in the ascending limb of Loop of Henle (so its a “loop” diuretic)
- Blocks Na+/K+/2Cl- co-transporter
- stops salt moving, so stops water being rebasoped,
- which causes diuresis
- Allows up to 20% of filter Na+ to be excreted, causing enormous natriuresis (losing sodium) and diuresis.
Why do we use furosemide
Uses: cardiac failure, renal failure
What are the side effetcs of furosemide
- K+ loss (and subsequent hypokalemia), leading to cardiac dysrhythmias (particularly when administered with digoxin)
- CVS: link prolong time for AP, so that (check that out)
Other side effects:
- Hypovolaemia (assessed by acute weight changes)
- Mild metabolic alkalosis (distal Na+/H+ exchange)
- Loss of Mg2+ and Ca2+ (loss of filtrate +ve charge).
What do Thiazides do
- Block Na+/Cl- co-transporters
- stops ions from being reabsorbed, which means less water is reabsorbed
Where do thiazides work
Act in the distal tubule
its a moderately effective diuretics
Why do we use thiazides
- Uses:antihypertensive
- As a diuretic, in conjunction with furosemide
What are the side effects of thiazides
- increased uric acid
- Hyperglycaemia
- Hyponatraemia
What do we use spironolactone for
we use it to block the effects of aldosterone
Where does Spironolactone act
Acts in the Collecting tubules and ducts
When we would prescribe spironolactone
heart failure (K+ sparing diuretic)
What are the sides effects of spironolactone
Gynaecomastia
menstrual disorders, testicular atrophy hyperkalaemia
What drug is newer than spironolactone
Eplerenone
mineralocorticoid inhibitor but expensive
What is the mechanism of aquaretic drugs
- ## Causes water loss without salt lossHow
-Acts onV2 receptor as antagonists (Vaptans; e.g tolvaptan)
What are Aquaretic drugs used to treat
used to treat chronic hyponatraemia (low sodium levels)
-SIADH
Where do Aquaretic drugs act on in the kidneys
Late portion of the distal tubule and the collecting duct to block the action of AVP (vasopressin or ADH)
How do we inhibit the renin-angiotensin system to control blood pressure
he asked an MCQ about one of these drugs
- ACE inhibitors
- Angiotensin 1 receptor antagonists
- Aldosterone receptor antagonists
- Renin inhibition
What drugs inhibit ACE
captopril, enalopril
What drugs inhibit the AT1 receptor
candesartan, irbesartan
What drug inhibits aldosterone
spironolactone
What drug inhibits renin
aliskiren
