Diuretics Flashcards
What are carbonic anhydrase inhibitors used for?
Glaucoma, reduces pressure in the eye
What are the types of diuretics? Name one from each group.
Thiazide: HCTZ, Thiazide-like: chlorthalidone, Loop diuretic: furosemide, Potassium-sparing: spironolactone, Osmotic: mannitol
Where do thiazide diuretics work?
DCT
Who should not take thiazide diuretics or loop diuretics?
People with sulfa allergies - might be directly related to sulfa or just might be another allergy
How much sodium reabsorption is done by thiazides?
10% since cells of DCT are impermeable to water
What are the 2 thiazide drugs to know?
Chlorthiazide, HCTZ
What is the only injectable thiazide?
chlorthiazide
What are the uses for HCTZ?
HTN, HF
What is the initial effect of HCTZ on BP?
BP will drop initially then come back up slightly and normalize - when pts start the drug they will pee a lot and then not as much
Name the “ceiling diuretics” - what does it mean?
Thiazides, have to cap the doses (50mg) - increasing the dose beyond the max will have no effect
What ions are excreted with thiazides?
potassium, sodium, chloride, magnesium
What are the effects of thiazides?
loss of fluid, vasodilation, reduced peripheral vascular resistance
How long does it take a thiazide to drop BP?
1-3 weeks
When is calcium retention a problem in people taking thiazides?
If they have already high levels
What do high doses of thiazides show?
increased rates of mortality
What are the ADR for thiazides?
hyponatremia, hyperuricemia, volume depletion, hypercalcemia, hypersensitivity, hyperglycemia, hyperlipidemia, hypokalemia
What labs should be ordered to monitor electrolytes in people taking thiazides?
BMP with serum magnesium
What are the thiazide-like diuretics that are used in combination with other diuretics when pts become refractory to diuretic therapy?
Metolazone, indapamide
Which thiazide-like diuretic has the longest duration of action?
Chlorthalidone
What is chlorthalidone derived from?
carbonic anhydrase inhibitors
Where do loop diuretics work?
the ascending loop of henle
What percent sodium reapsorption occurs with loop diuretics?
25-30%
How is sodium reabsorbed by loop diuretics?
Na/K/Cl co transporter
How is sodium reabsorbed by thiazides?
Na/Cl transporter
What are the 3 loop diuretic you need to know?
bumetanide, torsemide, furosemide
What are “high ceiling” diuretics?
loop diuretics - have huge doses
What are the effects of loop diuretics?
increased excretion of Na, Cl, K, Mg, and Ca, reduced renal vascular resistance
How is hypocalcemia avoided with loop diuretics?
most calcium is reabsorbed in the DCT
What CrCl is too low to use loop diuretics?
40ml/min
What is the bioavailability of oral furosemide?
50% - switch IV to oral and 2x the dose
What is the best time to take loop diuretics?
5am/5pm
What are uses for furosemide and torsemide?
HF, HTN
What are uses for bumetanide?
HF
What is the drug used primarily in treatment of states of volume excess (HF, nephrotic syndrome, acute and chronic renal insufficiency, cirrhosis)?
loop diuretics
How soon is the onset of loop diuretics?
rapid onset with symptom relief in hours or days
ADR for loop diuretics
Same as thiazides - more profound electrolyte loss (K and Mg) + ototoxicity
What drugs thus far have ototoxicity?
ethacrynic acid, aminoglycoside, loop diuretics
what are the 2 types of potassium sparing diuretics?
sodium channel blockers or aldosterone antagonists in the collecting tubules
Name the sodium channel blockers (potassium sparing diuretics)
triamterene, amiloride (hook these up with HCTZ since they have very mild effects)
What are the aldosterone antagonist potassium sparing diuretics?
spironolactone, eplereone
How do aldosterone antagonist work?
blocks stimulation of the Na/K exchange sites in the collecting duct
What type of diuretic has a hormonal effect?
spironolactone
What are uses for spironolactone?
HF
What are uses and effects for eplereone?
no hormonal side effects, HF, HTN
ADR for sodium channel blockers?
leg cramps, high BUN, uric acid, and K
ADR for aldosterone antagonists?
gastric upset (spironolactone), gynecomastia, menstrual irregularities
What are potassium sparing diuretics used in conjunction with?
thiazides - blunt hypokalemia that may occur with diuretics
What are uses for amiloride?
HF
How is mannitol administered?
IV
How do osmotic diuretics work?
inhibit sodium reabsorption in PCT and loop of henle
What are uses for mannitol?
reduce ICP and ocular pressure - not used in HTN
What are ADR of potassium supplements?
asymptomatic hyperkalemia, ECG changes, GI symptoms
Who should not take potassium supplements?
people with renal insufficiency since they can’t get K out
What is a potassium supplement you can give pts?
potassium chloride (K-Dur, Slow-K)
If in the ED and a pt is hypokalemic, what is the best plan of action?
give 40 mEq/L of potassium chloride 2 doses 4 hours apart
What do most patients on loop diuretics experience as their potassium levels?
3.5 mEq/L
When should electrolytes be measured in a pt on a diuretic?
baseline, 1 week, 1 month, periodically
What are 3 good uses for diuretics?
HTN, HF, kidney disease
What should be considered when prescribing diuretics to geriatric populations?
fall in GFR decreases diuretic effect with thiazides - give low dose chlorthalidone
What diuretics should be given to adolescents?
thiazides and spironolactones, avoid furosemide in premature infants with RDS, side effects might not be apparent (change in personality, eating or sleeping) patterns/restlessness)
