33 clinical use of diuretics Flashcards
virtually all diuretics act by directly or indirectly inhibiting what?
ion transporters located on the lumenal membrane of the nephron
Drugs such as furosemide and thiazides act by directly binding to their transporters. However, __________ and _________ drugs do not because they work to indirectly inhibit their transporters?
1) Spironolactone
2) acetazolamide
Where do spironolactone and eperenone exert their effects?
From the blood side of the nephron. Note that this is opposite to most other diuretics as they work from the luminal (urine) side.
How do diuretics generally get into the urine?
Through organic acid or base transporters in the PCT. Not through the glomerulus!
Which diuretics are filtered through the glomerulus?
Osmotic diuretics such as glycerin and mannitol.
What is acetazolamide? Where does it work?
a carbonic anhydride inhibitor. It works in the PCT.
Do you become acidotic or alkalotic if the carbonic anhydrase enzyme is too severely inhibited?
It causes acidosis because the hydrogens are no longer being pumped out into the lumen to form carbonic acid, resulting in less bicarb being able to enter the cell.
Furosemide, bumetanide, and ethacrynic acid are all examples of what?
Loop diuretics
In what part of the loop do Loop diuretics work? What do they block?
work in the thick ascending part and block the Na+/K+Cl- symporter.
where does metolazone work? what type of diuretic is it?
Functions in the DCT and it is considered to be a thiazide like diuretic.
Where do you find the aldosterone receptor?
It is located inside the principal cells that are located in the collecting ducts.
Which drugs inhibit ENaC? (2x)
1) Amiloride
2) Triamterene
T/F If you have heart disease, you should limit the amount of salt you eat per day to about 2000mg?
TRUE
What is one of the largest problems associated with giving a diuretic that acts in the PCT or in the nephron loop?
The TGF (tubuloglomerular feedback system of the macula. It causes a decreased urine flow if it senses too much Na+ in the urine flowing past it.
What affect does furosemide have on the osmotic gradient of the renal medulla?
it decreases the medullary osmotic gradient because not as much sodium is being reabsorbed like normal.
what affect does furosemide have on capacitance?
it increases venous capacitance resulting in decreased left ventricular filling pressure.
Diuretics help the patient by getting rid of extra fluid within cells and around cells (third spacing). What main functions do they have on the lungs?
decrease pulmonary edema
decrease SOBi
ncrease O2 saturation
What are the 7 major complications of using furosemide
1) sodium depletion
2) Hypomagnesemia
3) ototoxicity
4) uric acid retention
5) decreased renal perfusion
6) alkalosis
7) Hypokalemia
Which diuretic is used to reduce BP, are well tolerated, and are inexpensive?
Thiazide diuretics
Early on with diuretic use, the major hypotensive effect is to?
reduce extracellular fluid volume
Chronic reduction of BP results mainly from?
reduction in pulmonary vascular resistance (PVR)
T/F diuretic based therapy decreases the incidence of CHF in the elderly?
TRUE
T/F thiazides decrease Ca+ excretion?
TRUE
Diuretics can decrease what?
1) BP
2) PV
3) TPR
4) CO (only initially)
Complications of thiazide diuretics include (7)?
volumedepletion hyponatremia hypokalemia hypomagnesemia hyperlipidemia hyperuricemia glucose intolerance
Nephrotic syndrome consists of which 3 things?
1) proteinuria
2) hypoalbuminemia
3) edema
T/F Patients using diuretics such as thiazides often have high cholesterol?
true because of the hyperlipidemia effect
what is the goal behind using an oral diuretic for edema?
to reduce discomfort associated with the edema and not necessarily to eliminate the edema completely.
What do you have to change up when the patient you are trying to treat has nephrotic syndrome?
you need a potent diuretic such as a loop diuretic.
If you have a patient that has diuretic resistance, what are 5 major things you should think about?
1) incorrect diagnosis
2) non-compliance
3) Inappropriate NaCl intake
4) Inadequate drug reaching tubule
5) decreased renal response
If you have decreased renal function and find that the diuretic is not working because of too much uremic toxins, what is the mechanism messing things up?
The uremic toxins are competing with the diuretic for the organic ion transporter in the PCT.
Decreased activation of RAA axis, NSAIDS, low GFR, and nephron adaptation all result in what?
decreased renal response to diuretics
If you find that your loop diuretic is not working properly and you have eliminated most other potential problems such as lack of compliance, what should you do to help treat a patients edema?
Give them a diuretic such as thiazide or ENaC inhibitor. This is helpful because there do not deal with the TGF feedback system
Patients with cirrhosis generally have what?
secondary hyperaldosteronism which causes increased distal Na+ absorption.
T/F although loop diuretics are potent, due to the hyperaldosteronism, the excess sodium delivered to the distal tubule in reclaimed?
TRUE
What do spironolactone and eplerenone do?
aldosterone antagonists.
What side effects can the two aldosterone antagonists have?
1) hyperkalemia
2) Gynecomastia (Spironolactone)
3) agranulocytosis (Spironolactone)
4) hyponatremia
What is Lasix?
Furosemide
T/F most loop diuretics are long lasting?
false, they are short lasting.
uremic toxins compete with _______ for the organic ion transporter?
diuretics
If you have a loop diuretic that doesnt seem to be working well, what 2 things should you try?
1) increase dose to 2x daily
2) add a thiazide diuretic
Ototoxicity is associated with?
All loop diuretics but especially furosemide.
Furosemide can have major complications that include (5)?
sodium depletion ototoxicity alkalosis uric acid retention hypocalcemia.
