Lecture 21: Diuretics Flashcards
where do loop diuretics act
Thick ascending loop of henle on the NKCC2 transporter
The thick ascending loop of henle is impermeable to ___
Water
What ions are reabsorbed in thick ascending LOH
Na+, Cl-, K+, Mg2+, and Ca2+
What type of diuretic is furosemide
Loop diuretic
What are the pharmacodynamics of furosemide
Acts on thick ascending LOH, inhibits NKCC and reduces Na+ reabsorption
Loop diuretics increase the excretion of __ and ___
Mg2+ and Ca2+
Loop diuretics cause __kalemia and what does it do to pH
Hypokalemia, and alkalosis
How do loop diuretics cause hypokalemia
Na+ load is greater at CD and therefore the exchange between Na+ reabsorption and K+ loss is greater
Loop diuretics cause __kalemia __chloremic alkalosis
Hypokalemia hypochloremic alkalosis
Loop diuretics induce synthesis of __ which causes vasodilation
Prostaglandin
What do loop diuretics primarily relieve and how
Pulmonary congestion by increasing systemic venous capacitance/vasodilating via PG synthesis
What species is furosemide labeled for
Dogs, cats, horses and cattle
Furosemide is the drug of choice for ___
Rapid mobilization of edema fluid
Furosemide increases Ca2+ excretion and therefore is used in the treatment of __ and ___ in dogs and cats
Hypercalcemia and hypercalciuric nephropathy in dogs and cats
What does furosemide prevent in race horses and how
Exercise induced pulmonary hemorrhage and epitaxis via vasodilatory effects of PG synthesis
What are some furosemide related toxicity symptoms
- Abnormalities in fluid and electrolytes
- hypokalemia
- hypocalcemia
- hypomagnesemia
- hyperuricemia
- hypovolemia
- hyponatremia
hypokalemia induced furosemide diuresis potentiates ___ toxicity
digoxin
What type of diuretic is hydrochlorothiazide
Thiazide diuretic
Where do thiazide diuretics act
NCC transporter in ascending limb of DCT
What is the mechanism of action of thiazide diuretics
Inhibit Na+ reabsorption at cortical diluting site
Thiazide diuretic effects are dependent on ___ synthesis and may be inhibited by ___
PG, NSAIDS
Thiazide diuretics are a stimulus for aldosterone which causes ___
Hypokalemia
Thiazide diuretics cause a decrease in ___ excretion
Ca2+
What are some toxicity signs from thiazide diuretics
Hypokalemia metabolic alkalosis, hyperuricemia, hypercalemia
What are thiazide diuretics commonly used for
- Quarter horses with hyperkalemic periodic paralysis
- Long term treatment for dogs and cats in HF (furosemide is DOC)
- Prevention of calcium oxalate uroliths
What drug is FDA approved for use in dairy cattle for treatment of post partum udder edema (labeled product d/c in US)
Chlorothiazide
Where do potassium sparing diuretics act
Cortical collecting tubule
What type of diuretic is spirnolactone
Potassium sparing
How does spironolactone work
Competitive inhibitor of aldosterone, promotes Na+ excretion and inhibits K+ excretion
When is spironolactone used
CHF that is unresponsive to furosemide, hepatic cirrhosis, nephrotic syndrome, and severe ascites
Caution should be taken when use spironolactone with __ inhibitors. Why?
ACE inhibitors, because both block aldosterone and can result in hyperkalemia
How is mannitol administered
IV only, not absorbed orally- will produce diarrhea
When is mannitol used
1.prophylaxis acute renal failure
2. Reduce IOP
3. Reduce ICP
4. Protect kidney against nephrotoxic substances
Mannitol may produce ___in HF patients
Pulmonary edema
Where do carbonic anhydrase inhibitors act
proximal tubule
What class of drug is acetazolamide
Carbonic anhydrase inhibitor
What is the mechanism of action of acetazolamide
Inhibit CA enzyme and block HCO3- reabsorption, reduces Na+ reabsorption and increases Na+/K+ exchange
What is acetazolamide used for
- Reducing aqueous humor production in glaucoma patients
- Hyperkalemic periodic paralysis in quarter horses
When is acetazolamide contraindicated
Hepatic cirrhosis (decreases ammonia excretion)
What is the blood pH of patient on loop diuretics
Alkalosis
What is the blood pH of patient on thiazide diuretics
Alkalosis
What is the blood pH of patient on potassium sparing diuretics
Acidosis
What is blood pH of patient on carbonic anhydrase inhibitors
Acidosis
