WEEK 9: 9.5 Medications That Affect The Kidneys Flashcards
(30 cards)
What are diuretic drugs?
drugs that increase urine production
How do diuretics increase urine production?
By moving water and solutes from vascular space to urine
they act on specific targets on renal tubular cells
inhibit sodium reabsorption and water reabsorption
When are diuretic drugs usually used?
When there is excess fluid in tissues, to correct fluid oedema states (heart failure, renal disease, hepatic disease)
Reduce blood pressure in hypertension
What is normal GFR
120 mls/min
How much filtrate is reabsorbed in tubules?
99%, only 1% is excreted as urine
Where do loop diuretics act
the ascending loop of henle
What receptor do loop diuretics block?
Na+/K+/2Cl-
When are loop diuretics diagnosed?
For patients in edematous states like chronic heart failure
What are examples of loop diuretics?
furosemide (most common) and bumetanide
What do doctors consider before prescribing a patient with loop diuretics?
If the patient has an allergy to furosemide (they can prescribe ethacrynic acid)
What are symptoms of loop diuresis
dramatic diuresis
polyuria, incontinence, nocturia
postural hypertension (due to dehydration)
What needs to be monitored in a patient prescribed with loop diuretics?
electrolytes: decrease in K+ H Mg and Ca
renal function
edema
weight
If the Na/K/2Cl co transporter is blocked, what does this result in the retention of?
sodium, chloride and water
Where do thiazides act upon, and what receptor do they block?
the luminal part of Na/K/2Cl co transporter in distal convoluted tubule
What are they diagnosed for?
milder edematous state as diuretic efficacy decreases (less sodium is reabsorbed in the DCT)
hypertension
What are the different types of thiazides?
hydrochlorothiazide - most common
chlorthalidone - rare
Indapamide - occasionally and used in combination with other drugs
How do doctors evaluate if a thiazide is suitable for prescription?
allergy to it
postural hypertension (will make it worse)
hyponatremia gout (low sodium)
If thiazides act on the Na/K/2Cl co transporter, what do they inhibit the reabsorption of?
Na+ and Cl-, resulting in retention of water in the tubule
Where does mineralcorticoid antagonists act upon, and what receptor do they block?
The collecting tubular cells, binding to the mineralocorticoid receptor
What do mineralcorticoid antagonists include?
Spironolactone
epleronone
What does spironolactone do?
it inhibits aldosterone mediated reabsorption of sodium, and secretion of potassium, hence preventing loss of potassium that occurs in thiazide/loop diuretics
What is a potassium sparing diuretic?
amiloride
What is acetazolamide?
A carbonic anhydrase inhibitor that inhibits reabsorption of HCP3- in the proximal convoluted tubule, with weak diuretic properties
What is the mechanism of action of ACE inhibitors
inhibit conversion of angiotensin I to angiotensin II (bc it blocks the enzyme to do so)
Inhibit breakdown of bradykinin
decrease vasoconstriction and aldosterone secretion
Results in low BP, reduced sodium/water retention
