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
what is the major concern with putting patients on dialysis?
it can drop BP severely
Which of the following electrolytes
derangement is associated with loop diuretics
intake?
A. Hypokalemia.
B. Hypernatremia.
C. Hypercalcemia.
D. Hypophosphatemia.
A
A 74-year-old patient with a 2-year history of congestive heart failure comes to the emergency department because of severe dyspnea. She has an allergy to sulfa medications. Her temperature is 37.7°C (99.8°F), blood pressure is 125/85 mmHg, pulse is 94/min, respirations are 32/min, and oxygen saturation is 91%. She has marked peripheral edema, as well as diffuse crackles throughout the lungs A plain film of the chest shows a large amount of fluid in the lungs. The patient is given a diuretic.
* Which of the following agents would be most appropriate?
* A. Acetazolamide
* B. Ethacrynic acid
* C. Furosemide
* D. Hydrochlorothiazide
* E. Mannitol
B (sulfa allergy)
A 73-year-old patient with a history of hypertension and heart failure comes to the physician because of breathlessness and worsening bilateral pedal edema. Her baseline chemistries are normal except for a mildly impaired baseline estimated glomerular filtration rate (eGFR) of 56 mL/min. She is prescribed a diuretic medication. Two weeks later, she is hypokalemic, hyponatremic, and hypocalcemic. Which of the following diuretics is most likely responsible?
* A. Amiloride
* B. Bendroflume
* C. Thiazide
* D. Eplerenone
* E. Furosemide
* F. Spironolactone
E
what are the side effects of thiazides?
hypercalcemia (opposite of loop diuretics) and hyperuricemia (increase risk of gout)
what are the side effects of hypercalcemia?
stomach upset, nausea, vomiting and constipation
what are the names of the thiazide and thiazide-like diuretics?
Hydrochlorothiazide
Chlorthiazide
Trichlormethiazide
Chlorthalidone
Metolazone
what is the mechanism of action of thiazides?
inhibit tubular resorption of sodium and chloride ions causing increased excretion of water, sodium and chloride. it also dilates the arterioles by direct relaxation
do thiazides affect potassium levels?
they cause excretion of potassium as well, but to a lesser extent than loop diuretics
thiazides are considered ______-line therapy for hypertension
first
why are thiazides so effective for treating hypertension?
mechanism is uncertain, likely has involvement in vasodilation
what can thiazides be used to treat?
hypertension
idiopathic hypercalciuria (peeing a lot of calcium— kidney stones)
adjunct treatment for CHF
osteoporosis (increases calcium reabsorption)
what are the metabolic side effects of thiazides?
hypokalemia, hyperglycemia, hypercalcemia, and hyperuricemia
how does increasing the dose of thiazide given impact its efficacy?
no significant increase in efficacy… low dose is comparable to high dose
what are two things that we should monitor for patients taking thiazides for a long period of time? (values that increase over time)
glucose and cholesterol levels
A 35-year-old patient presents to your office for a regular check-up. She has no complaints. On examination, her blood pressure is slightly elevated at 145/85. She is physically fit and follows a healthy diet. You decide to start her on antihypertensive therapy and prescribe hydrochlorothiazide.
How does this agent work?
* A. Inhibits reabsorption of sodium chloride in the early distal convoluted tubule
* B. Decreases net excretion of chloride, sodium, and potassium
* C. Increases excretion of calcium
* D. Inhibits reabsorption of sodium chloride in the thick ascending limb of the loop of Henle
* E. Interferes with potassium secretion
A
A 7-year-old patient is brought to the clinic by his mother. He
complains of sharp pain in his flanks, as well as dysuria and frequency.
The doctor orders a 24-hour urine calcium test, and the results come
back abnormal. After additional work-up, the child is diagnosed with
idiopathic hypercalciuria. What is a common type of medication used
for this aliment?
* A. Loop diuretics
* B. Carbonic anhydrase inhibitors
* C. Thiazide diuretics
* D. Potassium-sparing diuretics
* E. Osmotic diuretics
C
A 45-year-old patient with a history of medication- controlled hypertension presents to your office with complaints of a painful, swollen big toe on the left foot. You suspect gout and check his uric acid levels, which are elevated. From looking at the list of the medications the patient is taking, you realize that one of the medications may be the cause of his current symptoms. Which medication might that be?
* A. Acetazolamide
* B. Amiloride
* C. Spironolactone
* D. Hydrochlorothiazide
* E. Mannitol
D
what are the names of the drugs that are potassium-sparing diuretics?
Amiloride
Spironolactone
Triamterene
Eplerenone
what is an adverse reaction of potassium-sparing diuretics?
sexual dysfunction
what is the mechanism of action of potassium-sparing diuretics?
work in collecting ducts and distal convoluted tubules to interfere with sodium-potassium exchange and competitively bind to aldosterone receptors
what are potassium-sparing diuretics used to treat?
hypertension
reversing potassium loss caused by other drugs
hyperaldosteronism
ascites aka liver disease (a condition in which fluid collects in spaces within your abdomen)
what are the side effects of potassium-sparing diuretics?
what are men-specific SEs?
what is a women-specific SE?
weakness, hyperkalemia
men can have gynecomastia and impotence
women can have amenorrhea (lack of menstruation)
what is the most common form of secondary hypertension?
Aldosteronism
what does the drug mannitol do?
increase RBF and GFR
attracts fluid from the interstitial compartment
increase urine flow and prevents obstructive myoglobin casts
when do we use mannitol?
-early rhabdomyolysis (damaged muscle tissue releases its proteins and electrolytes into the blood)
-to increase GFR during renal hypoperfusion
-prevent anuria (failure of the kidneys to produce urine)
list the drugs that are carbonic anhydrase inhibitors
acetazolamide
methazolamide
dichlorphenamide
what is the mechanism of action of carbonic anhydrase inhibitors?
it blocks the action of carbonic anhydrase which helps make hydrogen ions available for exchange with sodium and water in the proximal tubules. Essentially, it prevents the exchange of hydrogen ions with sodium and water
when do we use carbonic anhydrase inhibitors?
for edema when other diuretics are not effective
are carbonic anhydrase inhibitors more or less potent compared to loop/thiazides?
less potent
why are carbonic anhydrase inhibitors only used to treat edema for roughly 48 hours?
they induce metabolic acidosis which reduces their diuretic effect in 2-4 days
what are the symptoms of metabolic acidosis? what substance in specific is being depleted?
nausea, vomiting, fast breathing, and lethargy.
HCO3-
what are the two main side effects from carbonic anhydrase inhibitors?
metabolic acidosis and drowsiness
what is the interaction b/w ACE-Is and potassium-sparing diuretics?
increased hyperkalemia and cardiac problems
what is the interaction b/w beta-blockers and thiazides?
hyperglycemia, hyperlipidemia, and hyperuricemia
