Diuretics Flashcards
What is the definition of a diuretic?
How do they do this?
- Drugs that increase the rate of urine flow.
- Increase the rate of sodium excretion usually as sodium chloride.
What are 7 classifications of diuretics?
- Osmotic diuretics
- Loop or high ceiling diuretics
- Thiazide diuretics
- Potassium-sparing diuretics
- Carbonic anhydrase inhibitors
- Cardiovascular diuretics
- Physiological diuretics
What are examples of cardiovascular diuretics?
- Digitalis (digoxin)
- Phosphodiesterase Inhibitors: Aminophylline, Inamrinone , Milrinone
What is the therapeutic use of cardiovascular diuretics?
Treatment of edema associated with congestive heart failure.
Water as a physiological diuretic is used for what?
Used in compensated chronic interstitial nephritis of dogs.
Sodium chloride as a physiological diuretic is used for what?
Used in urolithiasis in sheep, calves and cats.
Name 4 examples of osmotic diuretics.
- Mannitol
- Urea
- Glycerin
- Isosorbide
Where do osmotic diuretics act in the nephron?
Proximal convoluted tubule and thick ascending loop of henle
What is the mechanism of action for osmotic diuretics?
Where do they act?
- May interfere with transport mechanisms in the thick ascending limb increasing the urinary excretion of NA+, K+, Ca2+, Mg2+, Cl-, HCO3- and phosphate.
- Act in both the thick ascending loop of Henle (primary site) and proximal convoluted tubule (secondary site).
Do osmotic diuretics increase renal blood flow and renal medullary blood flow?
Yes
Do osmotic diuretics increase or reduce medullary tonicity?
How do they do this?
- Reduce
- By an osmotic effect in the tubule.
What are 5 therapeutic uses of osmotic diuretics?
- Treatment of cerebral edema
- Treatment of glaucoma
- Treatment of acute renal failure
- Mobilization of edema fluid
- Used in patients with drug overdose
How are urea and Mannitol administered?
IV
How are glycerin and isosorbide administered?
Orally
Is Mannitol metabolized?
How is it eliminated?
- No
- Rapidly by the kidney
What are 3 examples of Loop or High Ceiling diuretics?
- Furosemide
- Bumetanide
- Ethacrynic acid
What is the mechanism of action of loop or high ceiling diuretics?
- Inhibit Na2+/K+/2Cl- symporter at the luminal membrane in teh thick ascending loop of Henle.
- This also results in inhibiting paracellular reabsorption of Na+, Ca2+, Mg2+.
You don’t use mannitol with what condition?
Generalized edema
Which are the most effective diuretics?
Why?
- Loop diuretics
- Approximately 25% of the filtered Na+ is reabsorbed in the thick ascending loop.
With loop or high ceiling diuretics, increasing Na+ delivery to the late distal tubule and collecting duct has what effect?
Increases depolarization of the luminal membrane creating a lumen-negative transmembrane potential difference.
Can you see allergies with loop or high ceiling diuretics?
Is there cross-hypersensitivity among the different drugs in this category?
- Yes
- Yes
What is the result of loop or high ceiling diuretics facilitating K+ excretion through K+ channels in the luminal membrane of the principal cells and H+ secretion in type A intercalated cells into the lumen?
Hypokalemia and systemic alkalosis
What also contributes to hypokalemia and systemic alkalosis that can be seen with loop or high ceiling diuretics?
Stimulating the renin-angiotensin-aldosterone system.
Do loop or high ceiling diuretics increase or decrease total renal blood flow?
What might this mechanism involve?
- Increase
- Prostaglandins
Do loop or high ceiling diuretics increase or decrease systemic venous capacitance?
This may be mediated by what?
- Increase
- Prostaglandins
What are 3 therapeutic uses of loop or high ceiling diuretics?
- Treatment of acute pulmonary edema and pulmonary congestion.
- Treatment of generalized edema associated with congestive heart failure, chronic renal failure and liver cirrhosis.
- Combined with isotonic saline to treat hypercalcemia and to prevent volume depletion.
Loop or high ceiling diuretics may be useful in treating what condition?
Acute renal failure
What can be used to treat intracranial pressure and udder edema?
Loop or high ceiling diuretics
What is used for the treatment of exercise-induced pulmonary hemorrhage in horses?
What type of a diuretic is this?
- Furosemide
- Loop or high ceiling diuretic
Can loop and high ceiling diuretics be used in patients with drug overdose?
Yes