Exam 1; Diuretics Flashcards
What is the definition of a diuretic
any agent that causes a net excretion of water and Na+
What two main things are diuretics used for clinically
hypertension; decreasing blood volume and some cause vasodilation
to reduce edema; in heart failure; kidney retains H2O and Na, water accumulates in the interstitial space
This is designed to eliminate unwanted molecules (Na & H2O) and to conserve essential ions and molecules
normal kidney function
What is the flow of molecules in the proximal convoluted tubule
removal of Ca++, Na+, HCO3-
exchange of organic molecules
What is the flow of water through the renal tubule
water can freely pass through the tubule; following the osmotic gradient
What is the flow of molecules in the loop of Henle
removal of K+, Cl-, and large amounts of Na
What is the flow of molecules in the distal convoluted tubule
removal of Na+, Cl-, Ca++
What is the flow of ions in the collecting duct
Na+/K+ exchanger (Na out, K in)
removal of H2O
True or False
Thiazide diuretics have a low therapeutic index
False; they have a high index
What is the mechanism behind thiazide diuretics
they inhibit Na+ transport out of the DCT; water follows and they are excreted in the urine
What are two other affects of thiazide diuretics
they cause direct vasodilation (often drug of choice in treating hypertension)
they decrease the excretion of Ca++ (Ca++ retention)
What are five side effects of thiazide diuretics
hypokalemia (loss of Ka due to Na/K exchanger)
increase serum LDL and triglycerides
decrease uric acid secretion; gout
inhibit insulin secretion
contains sulfur ions; may cause allergic reaction
What are two examples of thiazide diuretics
chlorothiazide
hydrochlorothiazide
What are four examples of loop/high ceiling diuretics
furosemide
ethacryncic acid
bumetanide
torsemide
What is the mechanism of action of loop diuretics
given orally or parentally
inhibit Na/Cl resorption from the ascending limb of the loop of Henle
Which is more efficacious, thiazides or loop diuretics
loop
How much urine/day can a patient excrete while on loop diuretics
10L
When are loop diuretics given clinically
in patients that don’t respond well to thiazides
patients with impaired renal function
patients with life threatening edema (pulmonary/cerebral)
What are 5 side effects of loop diuretics
dehydration hypokalemia (more Na to exchanger) hypocalcemia (increase Ca excretion) decreased uric acid secretion auditory nerve damage (especially if used with other ototoxic agents)
What are two examples of potassium-sparing diuretics; aldosterone antagonists
spironolactone
eplerenone
What is the mechanism behind potassium-sparing diuretics
blocking the aldesterone receptor; can prevent synthesis of Na/K+ exchanger
What are four side effects of potassium-sparing diuretics
takes a couple days to work
used with other diuretics to prevent K+ loss
used to treat excess aldesterone activity
can cause hyperkalemia
This potassium-sparing diuretic is a steroid, and can have anti-androgen effects (breast growth, etc.)
spironolactone
This potassium sparing diuretic has fewer interaction with other steroid receptors
eplerenone
These two potassium-sparing diuretics are inhibitors of what
triamterne
amiloride
Na+ transport in the distal tubule and collecting duct
Potassium-sparing diuretics which inhibit Na transport have what kind of mechanism
they prevent Na from getting into the exchanger by blocking Na channel
What is the effect/symptoms of potassium sparing diuretics which inhibit Na transport
the effect is more rapid and predictable than alderstone antagonists
hyperkalemia
What is the mechanism behind carbonic anhydrase (enzyme) inhibitors
inhibits HCO3- absorption in the PCT
What three things do carbonic anhydrase inhibitors (not primarily a diuretic) also treat
open angle glaucoma mountain sickness (decrease CSF formation) epilepsy (may be due to pH changes in the CNS)
This is an example of an osmotic diuretic
mannitol
What is the mechanism behind mannitol
non-metabolized sugar given as an IV and it remains in tubule and draws water into tubule and is secreted with the water
What is mannitol used to treat
used to maintain renal/urine flow after renal damage/trauma
also it lowers intracranial pressure
This diuretic increases globular filtration rate
methylxanthines (such as caffeine)
This diuretic releases ADH
ethanol
This triggers the synthesis of the Na/K exchanger
aldesterone
ADH (antidiuretic hormone) induces what
further reabsorption of H2O
This blocs the ADH receptor; in cases of excess ADH/retain too much water
conivaptin
