Diuretics Flashcards
Carbonic anhydrase inhibitors
acetazolamide
osmotics
mannitol
glycerin
isosorbide
urea
Na+/K+/2Cl- Blockers (Loop Diuretics)
furosemide
ethacrynic acid
bumetanide
Na+/Cl- blockers
hydrochlorothiazide
chlorthalidone
indapamide
inhibitors of ENaC
Amiloride
triameterene
Aldosterone antagonists
sprionolactone
epelereone
vasopressin (ADH) antagonists
tolvaptan
conivaptan
What are the two major clinical indications for diuretic therapy
- edematous states
2. hypertension
What are the major edema-causing conditions where diuretics are used
heart failure
pulmonary edema
nephrotic syndrome
hepatic cirrhosis
How is the steady state of the kidney defined?
intake = excretion
How do diuretics change steady state?
They create a new steady state where excretion is increased, to a point, over intake so homeostasis is less body fluid
What is diuretic “braking”
The adaptational effects of diuretic use that prevent endless excretion and volume depletion. Usually through modification of the Renin-Ang and ADH pathways
What is the most effective medication for edematous states?
Loop diuretics
What is the most effective medication for hypertension?
Thiazides (hydrochlorothiazide)
Decrease BP by decreasing cardiac output and decreasing total peripheral resistance (TPR)
What is the main determinant of extracellular fluid volume ECFV?
Na+
Therefore most diuretics aim to decrease EDFV by increasing Na+ excretion
Why prescribe a loop and thiazide combo?
Loop diuretics can be refractory due to compensatory Na+ reabsorption. Thiazides counteract this. However, this combo requires careful hemodynamic monitoring!
What can you do to counteract the K+ wasting of loops and thiazides?
Advise patient to restrict sodium and to take K+ supplements.
If this is not enough, add K+ sparing diuretics
List the major classes of diuretics in order based on their site of action on the nephron: PCT through CD
Carbonic Anhydrase inhibitors: PCT (plus CD)
Osmotic Diuretics: tDLH (plus PT, CD)
Loops (Na+K+2Cl- blockers): TALH
Thiazides (Na+Cl- blockers): DCT
ENaC inhibitors: late DCT, CD
Aldosterone (Mineralocorticoid)Antagonists: late DCT, CD
Vasopressin (ADH) Antagonists: CD
Which diuretics are K+ wasting?
Loops: Furosemide, ethacrynic acid, bumetanide
Thiazides: Hydrocholorothiazide, chlorthalidone (indapamide)
Why doesn’t a patient on diuretics end up looking like a raisin?
Diuretic Braking