Diuretics Flashcards
carbonic anhydrase inhibitors prevent the reabsorption of what
HCO3 (bicarb)
Example of osmotic diuretic?
Mannitol
pt w/ osteoporosis and mild HTN needs diuretic. What would be best choice
thiazide diuretic
*acts on DCT and Ca++ is being reabsorped (better for osteoporosis). Only one that has vasodilatory effect on vasculature.
1st line drugs for HTN
Can always trust ACE.
CCB, ARBs, Thiazide diuretics, ACEI
Will aldosterone antagonists cause hypokalemia?
Nope
Can cause hyperK+
Why should a pt taking furosemide not take an NSAID for their h/a?
Blockage of prostaglandin synthesis reduces efficacy of loop diuretics
What 2 drugs do you not take NSAIDs with?
-ACEIs
-Loop diuretics
NSAIDs constrict the ________ arteriole in the kidney
afferent
Angiotensin II constricts the ________ arteriole in the kidney
efferent
Which diuretic for pt w/ mineralocorticoid excess?
Spironolactone
*acts on aldosterone (aldosterone antagonist) and aldosterone is a mineralocorticoid
Loop diuretics block which cotransporter?
N/K/2Cl
Defeciency in parathyroid hormone (PTH) causes what electrolyte imbalance?
Low Ca++
___________ diuretics & _________ __________ antagonists are aquaretics and are not directly natriuretic
-Osmotic diuretics
-ADH antagonists
What 3 compounds/ions get reabsorbed in the proximal convoluted tubule (PCT) of the kidney?
-Na+ (65% of Na+ get reabsorbed here)
-H2O
-HCO3 (Bicarb)
What compound/ion gets reabsorbed in the descending limb of the loop of henle in the kidney?
H2O
What 2 compounds/ions get reabsorbed in the ascending limb of the loop of henle?
-Na+ (25% of Na+ reabsorption occurs here)
-H2O
What 2 compounds/ions get reabsorbed in the early distal convoluted tubule (DCT) in the kidney?
-Na+ (5%)
-H2O
What 2 compounds/ions get reabosorbed in the late distal convoluted tubule (DCT) and collecting duct (CD), and what 2 substances are required for the reabsorption to occur?
-Na+ (5%)
-H2O
*Aldosterone is required here for Na+ reabsorption and ADH is required for H2O reabsorption to occur. This is the differrence between the early & late DCT and why K+ sparing diuretics work here in the late DCT.
*K+ also gets excreted largely in the CD
What part of the tubule do thiazide diuretics work on?
Early DCT (5% of Na+ reabsorption)
What is MOA of mannitol (osmotic diuretic). AKA why does is cause massive aquaresis.
Mannitol is a large molecule that is able to get filtered throught the glomerulus into the tubules. Because its so large though, in the tubules it can’t be reabsorbed into the blood and it creates a strong osmotic pressure, pulling H2O into the tubules. Since the H2O gets pulled into the tubules it gets excreted via ureters.
What part of the tubule does Mannitol (osmotic diuretic) work?
-PCT
&
-Desc. limb of loop
What diuretic drug works soley on the PCT?
Carbonic anhydrase inhibitors (CAIs)
What is the MOA of CAIs?
Blocks the enzyme carbonic anhydrase which dissasociates HCO3 (into H2O & CO2) via the buffer equation in order for it to be reabsorbed. When it gets absorbed into the cell (the wall of the PCT, on the way to the bloodstream) it dissasociates back into HCO3 + H+ and the H+ drives the Na+ pump that reabsorbs Na+.
With the enzyme and this pump inhibited, the reabsorption of HCO3, Na+, and H2O is blocked.
Loop diuretics block the __________ transporter in the ascending limb of the loop
-Na/K/2Cl transporter
Loop diuretics increase secretion of Na+, Cl, H2O, ____, & ____ into the urine
-Ca++ & Mg++
Thiazide diuretics can cause an increase of serum ______
-Ca++
Thiazide diuretics block the _________ cotransporter in the early DCT
-Na/Cl cotransporter
In the acending limb of the loop of henle (AKA think ascending limb), Ca++ & Mg++ are driven out of the tubules to the blood via the ___________ pathway
-Paracellular pathway
*literally between the cells within the wall of the tubules to the blood stream d/t concentration gradients
Ca++ reabsorption in the early DCT is regulated by __________
-parathyroid hormone (PTH)
The _______ ________ is the most significant site of K+ secretion within the tubules
Collecting Duct
Principal cells in the collecting duct are responsible for _______ tranpsort
Ion transport
Intercalated cells in the collecting duct are responsible for _______ transport
Acid-base
In the late DCT, or collecting duct, the reabsorption of Na+ via ENaC channels (epithelial Na channel) & the secretion of K+ is regulated by ___________
Aldosterone
ADH facilitates H2O reabsorption in the collecting duct via insertion of _________ channels
Aquaporin channels
Vasopressin 1 receptors are found in the ________ & ______ while vasopressin 2 receptors are found in the _________
-Vasculature & CNS
-Kidney
___________ antagonists act affect ion transport in the PCT and do not cause K+ waisting
Adenosine antagonists
Prostaglandins, specifically PGE2, blunts _____ reabsorption in the TAL of the loop as well as ______-mediated H20 transport in the CD
This enhances the action of loop diuretics!
-Na++
-ADH mediated
NSAIDS block _________ synthesis and decrease their enhancement of _______ diuretics
-prostaglandin synthesis
-loop diuretics
NSAIDs _________ the effect of loop diuretics
-decrease/lower
What is urodilatin?
A natriuretic peptide (like ANP,BNP,CNP) that functions only in the kidney
Urodilatin is made in the ________ of the kidney and blunts ______ reabsorption
-DCT of kidney
-Na+ reabsorption
Urodilatin __________ afferent vasomotor tone and __________ efferent vasomotor tone leading to an increase in GFR
-decreases afferent
-increases efferent
__________ is a recombinant peptide that mimics the activity of urodilatin
Ularitide
COX-___ paricipates in the synthesis of prostaglandins that enhance the action of loop diuretics. Therefore NSAIDs can blunt the effects of loop diuretics.
COX-2
Characteristic adverse effect of loop diuretics?
*hint - not involved w/ renal system
Ototoxicity
Loop & thiazide diuretics cause enhanced reabsorption of _______ ______ in the proximal tubule and therefore can precipitate ________ attacks
-Uric acid
-Gout attacks
DO NOT give thiazide diuretics to pts with a _______ allergy
Sulfa
*thiazides are sulfa containing drugs
(t/f) thiazide diuretics can cause hyperglycemia
True
*d/t inhibiting insulin release by hyperpolarizing beta cells
Thiazides can cause a 5-15% increase in serum _________
Cholesterol
What are the two classes of diuretics that are K+ sparing?
-Aldosterone antagonist (spironolactone)
-ENaC Blockers (amiloride, triamterene)
Why do loop & thiazide diuretics cause low serum K+?
*2 reasons
-They cause increase tubule Na+ delivery to distal tubule sites which causes K+ waisting
-these diuretics can cause low intravscular volume, leading to high levels of aldosterone, which increases K+ secretion
Giving K+ sparing diuretics w/ other drugs that inhibit the RAAS, such as ________, ________ & _________ can lead to hyperkalemia
-BBs
-ACEIs
-ARBs
(t/f) ok to give diltiazem w/ K+ sparing diuretic
Nope
*Diltazem is a stron CYP3A4 inhibitor and can increase blood levels of some K+ sparing diuretics (eplerenone especially)
Dont give K+ sparing diuretics w/ strong _________ inhibitors
-CYP4A3 inhibitors
The _________ tubule and ________ limb of the LOH are freely permeable to H2O
-PCT
-Dsc. limb of LOH
High levels of serum _______ cause osmotic diuresis
Glucose
