Diuretic Agents Flashcards
where in the kidney do osmotic diuretics such as mannitol act and what does it do?
the proximal convoluted tubule (before descending loop of henle) to increase GFR
where in the kidney do loop diuretics such as furosemide act and what does it do?
ascending loop of Henle to prevent reabsorption of sodium and chloride
where in the kidney do thiazides act and what do they do?
early distal convoluted tubule (right after ascending loop) to prevent reabsorption of sodium
where in the kidney do antikaliuretics (potassium-sparing diuretics) such as spironolactone act and what does it do?
the late distal convoluted tubule (right after early distal) to compete with aldosterone for receptor sites to increase sodium chloride and water excretion while conserving potassium
all loop diuretics have a risk of what adverse reaction?
ototoxicity
what are the benefits of furosemide?
it is good for patients with heart failure and overall fluid management
what are the benefits of bumetanide?
it is the most potent diuretic, but it has a very short half-life
what are the benefits of torsemide?
it has a more predictable absorption rate compared to furosemide, the main reason it is not prescribed over furosemide is due to how expensive it is
what are the benefits of hydrochlorothiazide?
it is good for patients with hypertension since it is a good vasodilator
what is the benefit of ethacrynic acid? why do we not used it as often?
it is the only diuretic that is not a sulfa moiety, so it can be used to reduce edema in patients with sulfa/diuretic allergies. it is not used as often because it has the highest incidence of ototoxicity
loop diuretics are very potent at increasing water excretion. However, what ion do they also cause to be excreted? why is this a concern?
potassium, potassium levels need to stay between 4-5. if it goes too low it increases the risk of arrhythmia
which loop can also be used to treat liver disease?
torsemide
if a patient is given 20mg IV of furosemide, what strength should be prescribed to be taken PO?
40mg
in regards to sodium reabsorption, why is the ascending loop of henle a good target for preventing reabsorption? (mechanism of loop diuretics)
because 20-25% of sodium is reabsorbed at this location
what are the metabolic side effects of loop diuretics?
hypokalemia, hyperglycemia (likely due to hypokalemia), hyperuricemia (elevated uric acid level in the blood), and hypocalcemia
what are the symptoms of hypokalemia?
constipation, heart palpitations, fatigue, and muscle weakness/spasms
what are the symptoms of hyperglycemia?
excessive thirst, fatigue, and blurred vision
what is an adverse reaction to hyperuricemia?
can exacerbate gout
what are the symptoms of hypocalcemia?
muscle cramps/weakness/spasms, fatigue and irritability
after treating a patient with IV furosemide you come back to check on the patient. You notice that they are cold to the touch and their skin is noticeably dry. what is the suspected cause of these symptoms and what should you do?
patient is being given too much diuretic and the dose should be decreased
if initial dose of diuretic fails, what is the next step?
titrate up the dose by doubling it or add an additional agent such as a thiazide
after giving a patient diuretics, what is the minimum urine output we want?
2-3 mL/kg/hr
a patient was started on I.V furosemide and has reached max dose with urine output below 0.5 mL/kg/hr. what is the next step?
if no response, what is the next step?
if still no response, what is the next step?
initiate continuous furosemide infusion with a bolus dose
switch to a different loop diuretic and give continuous infusion
try combo therapy or consider dialysis