(3.2) Diuretics Flashcards
classes of K+ sparing
Na Channel blocker
Aldosterone antagonist
Loop diuretics
K wasting
Na K 2Cl blocker in the thick ascending loop
indirectly blocks Ca reabsorption
sulfa
furosemide class and application
loop diuretic
for Edema/heart failure/hepatic disease/renal disease
decrease preload and rapid dyspnea relief
treats HTN patients
WORKS REGARDLESS OF GFR AND RBF
Furosemide kinetics and concerns
IV 5 min (lasts 2 hrs)
PO 30-60 min (lasts 6-8 hrs)
IM 30 min
eliminated as unchanged drug in urine
hypokalemia hyponatremia hypocalcemia hypomagnesia hypochloremia and alkalosis
hyperglycemia
hyperuricemia
^ cholesterol and TG
ototoxicity! and is a sulfa!
torsemide
loop diuretic
longer half life than furosemide
better oral absorption and works in heart failure better
bumetanide
loop diuretic
with more predictable oral absorption
ethacrynic acid
loop diuretic
NOT a sulfa drug
Thiazide diuretics
K wasting
NaCl contransport blockers
in the DCT
‘thiazide’
hydrochlorothiazide class and application
thiazide diuretic
mild-moderate hypertension
treatment of edema
off-label calcium nephrolithiasis
DOES NOT WORK WELL WITH LOW GFR
hydrochlorothiazide kinetics/concerns
well absorbed orally with 65-75% availability
peak action in 2 hrs with total duration of 6-12hrs
excreted in urine unchanged
orthostatic hypotension
hypokalemia
hypomagnesemia
hyponatremia
hypochloremic metabolic alkalosis
hypercalcemia
hyperglycemia
hyperuricemia
SULFA drug
chlorothiazide
thiazide diuretic like HCTZ
poor oral absorption
chlorthalidone
thiazide diuretic like HCTZ
40-60 hr half life often preferred by HTN specialists
metolazone
long acting thiazide diuretic that is a favourite by cardiologists
Na channel blocker Diuretics
K SPARING
blocks epithelial sodium (ENaC) in the collecting ducts
small increase in Na excretion
blocks K excretion pathway
H Mg and Ca excretion decreased
amiloride class and application
Na channel blocker
counteracts K loss induced by other diuretics
off label for ascites
pediatric HTN
amiloride kinetics/concerns
orally <2 hour onset
half life 6-9 hrs with low GFR
excreted unchanged (50%) urine and (40%) feces
hyperkalemia hyponatremia hypovolemia hypercholermic metabolic ACIDOSIS dizziness/fatigue/headache nausea/vomiting/bloating/diarrhea
triamterene
Na channel blocker
for edema and off label HTN
duration is 6-9 hrs eliminated as drug metabolite
Aldosterone antagonist diuretics
K sparing
competitive antagonist of aldosterone receptors and partial androgen agonist
decrease Na entry through luminal Na channels and decreases Na-K ATPase on basolateral
spironolactone class and application
Aldosterone antagonist
counteracts K loss induced by other diuretics
treatment for primary hyperaldosteronism
off label to reduce fibrosis in post-mi heart
hirsutism and treatment of andorgenic alopecia in females
spironolactone kinetics/concerns
active metabolites including canrenone with half life of ~20 hours
steroid so slow on and off
hyperkalemia
amenorrhea/hirsutism/gynecomastia/impotence
tumorigen in chronic animal toxicity studies
epelrenone
more selective aldosterone antagonist that lacks sulfur
10x more expensive but lacks side effect severity of spironolactone
vaptans class
ADH antagonist
promotes excretion of free water
helps restore normal plasma Na conc
conivaptan class and application
vaptan V1 and V2
euvolemic and hypervolemic hyponatremia in pts who are
hospitalized/symptomatic/non-responsive to fluid restriction
need close monitoring
conivaptan kinetics/concerns
IV administration
CYP3A4 substrate
water loss can concentrate other electrolytes
eliminated primarily in feces as metabolite
orthostatic hypotension/fatigue/thirst/bed wetting and polyuria
tolvaptan
ADH receptor antagonist V2 specifically
orally
only used in hospital
must use < 30 days for hyponatremia any more can be hepatotoxic
licorice
glycyrrhizic acid
potentiates aldosterone effects in kidney and dose dependent increase BP 3-14 mmHg
example of herbal diuretics
chicory, dandelion leaves, fennel, golden seal, hops, marshmallow, stinging nettle, parsley, saffron, sage, sassafras, saw palmetto berries, skullcap, spearmint, St. John’s wort, strawberry leaves, uva-ursi, wintergreen and yarrow
carbonic anhydrase inhibitors
work in proximal tubule
made from sulfanilamide
inhibits Na/H exchange
causes hypercholermic acidosis
Azetazolamide/dorzalamide
carbonic anhydrase inhibitor
urinary alkalization
used for mountain sickness and glaucoma and metabolic alkalosis
causes metabolic acidosis, renal stones, and K+ wasting
mannitol
osmotic diuretic
works through oncotic pressure in the proximal tubule
ECV is increased and can increase HF
headache, nausae, vomiting, fluid, and electroly inbalance
mannitol therapeutic uses
prophylaxis of renal failure, keeps some fluid volume in the tubules to prevent them from collapsing when the glomerular filtration rate is very low
reduction of intracranial pressure
reduction of intraocular pressure (treating glaucoma) when patients haven’t responded to other therapy
