Diuretics Flashcards
diuretics as tx for the big 3
edema
HTN
heart failure
diuretic definition
a substance that increases the volume of urine
“increase excretion of sodium along with water”
mechanism of increased Na excretion
inhibition of Na reabsorption
NOT increasing glomerular filtration
which is absorbed better? furosemide or bumetanide?
bumetanide (and more potent)
Furosemide MOA
inhibit Na/Cl absorption at the TAL, K+ leaks back out into lumen
what two ions are lost with loop diuretics?
calcium/magnesium (usually absorbed across the TAL due to charge gradient)
urine osmolality on loop diuretics?
close to that of plasma - cannot maintain medullary conc gradient and thus cannot conc urine
how do loops initially relieve CHF sx?
via dilation of veins (prostaglandins?)
what drug blunts dilation and diuresis action of loops?
NSAIDS
what happens to starling forces on a loop?
hydrostatic down, oncotic up
after weeks of antidiuretic therapy?
intravascular volume is restored, but blood pressure remains low (as long as salt intake is not increased)
Loop SE’s that make sense
Volume depletion –> postural hypotension
Urination (sleep)
Depletion of total body sodium
Low serum K+ (most common SE) –> cramps/weakness
and arrhythmias
Hypokalemic alkalosis (H+ follows K+)
Mg/Ca depletion
Threaten blood flow to fetus (NOT used for P-E)
Loop SE’s that don’t make sense
Increased uric acid, glucose, cholesterol
Gout, worsen diabetes, increase coronary risk
Reversible deafness –> endolymph upset
Allergic rxns –> sunburn (SULFA)
Pancreatitis
Hepatorenal syndrome (DO NOT Tx PTS WITH LIVER FAILURE WITH FUROSEMIDE!!!)
Drug to NOT rx to pts with liver failure
Furosemide
Defect in Na/CL cotransporter
Giterman’s syndrome
why are thiazides helpful in osteoporosis?
cause retention of calcium
same prostaglandin effects as loops
thiazides for acute heart failure?
no, weaker and take longer to work than loops
most common use for thiazides
HTN
eventually reduction in TPR (prostaglandins?)
reduction in activity to pressors?
thiazide SE’s that can be explained
postural hypotention
extreme sodium depletion
increased K+ excretion
hypokalemic alkalosis (H+ excreted at the site where aldosterone works)
hypomagnesemia (tremors/twitches/arrhythmias/nausea)
thiazide SE’s that can not be explained
inhibit uric acid excretion --> gout decreased glucose tolerance inhibit insulin release hyperlipidemia reduce excretion of calcium (opposite to loops) pancreatitis sulfa allergy (sunburns) hepatorenal syndrome impotence
thiazide duration of action
longer than loops
SO if crit > 2.0, use loops instead so to not prolong aggravation of renal failure
K-sparing site of action
collecting duct
small diuretic effect
large K-sparing effect
Sprio/eplereno MOA
competitively inhibit aldosterone
lower K/Mg/H+ excretion
when are K-sparers only effective?
when adrenal is making aldo
Spiro/eplereno SE’s
*hyperkalemia (ACE-i's can predispose to this) gynecomastia, menstrual irregs anti-androgenic --> inc estrogen levels nausea, GI sx
triamter/amilo MOA
inhibit the Na/K exchange site (ENaC)
work regardless if aldo is present
Liddle’s syndrome
ENaC channel always on
Tx for Liddle’s syndrome?
Amiloride
Tri/Amilo SE’s
hyperkalemia (most worrisome b/c asymptomatic)
exaggerated on ACE-i’s
other effects of all K-sparers
magnesium-sparing
NO change in blood levels of uric acide/glucose/lipids
used to reduce edema in brain or eye
mannitol
effects common to all diuretics
initial volume depletion
rise in plasma renin/aldo
Na loss
Mg/K loss except K-sparers
calcium effects: loop v. thiazide
loop –> loss
thiazide –> spare
Lithium: furosemide v. thiazides
furosemide: no change
thiazides: reduce excretion of lithium
* decrease dose by 1/3 when adding a diuretic
NSAIDS do what to diuretics?
reduce anti-HTN effects
Digitalis
increased arrhythmias while on diuretics
loop diuretics interact how with antibiotics?
increase toxic effects on ear/kidney
amphotericin B with diuretics causes what
increased K+ loss
Thiazides do what to glucose levels?
elevate
