Diuretics

Question 1

Which class of diuretics also causes venous dilation and renal vasodilation (effects mediated by prostaglandins)?

Answer 1

loop diuretics

Question 2

also known as Lasix

Answer 2

furosemide

Question 3

the most efficacious diuretic class

Answer 3

loop diuretics

Question 4

the most commonly prescribed diuretic class

Answer 4

thiazides

Question 5

What is the significance of the loop diuretics causing renal vasodilation?

Answer 5

improved renal blood flow

Question 6

What are the major adverse effects associate with furosemide to be worried about?

Answer 6

hypokalemia, metabolic alkalosis, ototoxicity

Question 7

a loop diuretic that is used as a last resort (only when patient has hypersensitivity to other diuretics) due to associated nephrotoxicity and ototoxicity

Answer 7

ethacrynic acid

Question 8

What is the main clinical condition that furosemide treats?

Answer 8

edema (acute pulmonary edema, edema associated w/ CHF)

Question 9

Which 2 classes of diuretics differentially affect calcium (and how)?

Answer 9

• loop diuretics: increase calcium excretion

- thiazides: increase calcium reabsorption

Question 10

Describe the MOA of the thiazides.

Answer 10

They inhibit the Na+/Cl- cotransporter in the distal tubule, leading to increased calcium reabsorption.

Question 11

What is the main clinical indication of the thiazides?

Answer 11

HTN (can also be used in CHF or to prevent kidney stones by reducing calcium excretion)

Question 12

Which adverse effects are unique to the thiazides?

Answer 12

hyperuricemia, hyperglycemia, hyperlipidemia

Question 13

Which thiazide drug is the most efficacious of its class?

Answer 13

metolazone (strongest inhibitor of Na+ and water reabsorption; can also be used in patients with renal insufficiency)

Question 14

Which part of the nephron do the thiazides mediate their effect?

Answer 14

distal convoluted tubule

Question 15

Potassium sparing diuretics should never be given in the setting of __________.

Answer 15

hyperkalemia (or in patients on drugs or w/ disease states likely to cause hyperkalemia)

Question 16

Which drugs commonly cause hyperkalemia?

Answer 16

ACE inhibitors and potassium supplements

Question 17

Describe the MOA of spironolactone.

Answer 17

It is a competitive inhibitor of the aldosterone receptor, thus preventing aldosterone’s effect of increasing Na+ reabsorption.

Question 18

What are the main adverse effects associated with spironolactone?

Answer 18

hyperkalemia and metabolic acidosis (due to sparing of both K+ and H+); also can get gynecomastia, amenorrhea, impotence, and decreased libido due to off-target anti-androgenic effects

Question 19

What is the benefit of Eplerenone?

Answer 19

It is also a competitive antagonist of aldosterone binding to MR, but it does not inhibit testosterone binding (therefore, does not induce gynecomastia or other related anti-androgenic side effects).

Question 20

What is the main clinical indication for spironolactone?

Answer 20

liver cirrhosis (treats edema associated w/ cirrhosis)

Question 21

Describe the MOA of amiloride.

Answer 21

It blocks Na+ channels in principal cells of the collecting duct, causing mild diuresis. This decreases the driving force for K+ efflux, thus sparing K+.

Question 22

How is amiloride used?

Answer 22

Rather than being used alone, it is usually used in combination with loop and thiazide diuretics to prevent hypokalemic effects.

Question 23

What are the adverse effects associated with amiloride?

Answer 23

hyperkalemia (exacerbated by NSAIDs), muscle cramps, mild GI and CNS effects

Question 24

The active form of this drug can precipitate in the renal tubules and cause stones that obstruct flow.

Answer 24

Triamterene

Question 25

Which were the traditionally used ADH antagonists that are no longer used clinically due to potential for nephrotoxicity?

Answer 25

Demeclocycline (a tetracycline antibitioc) and Lithium (an antipsychotic)

Question 26

What are the clinical indications for ADH antagonists?

Answer 26

SIADH, euvolemic or hypovolemic hyponatremia, CHF

Question 27

This condition is resistant to loop diuretics and must instead be treated with aldosterone receptor antagonists.

Answer 27

hepatic cirrhosis

Question 28

What did the ALLHAT study tell us?

Answer 28

Anti-hypertensive and Lipid Lowering treatment to prevent Heart Attack Trial: lower-cost diuretic is superior to newer medications for the prevention of CVD; diuretics may be as effective as a single-drug treatment for high blood pressure

Question 29

Which diuretic class may be helpful in patients with calcium oxalate stones?

Answer 29

thiazides

Question 30

Which medical condition can lead to a diuretic-like effect?

Answer 30

Nephrogenic Diabetes Insipidus (due to loss of ADH effects)

Question 31

Most common cause of hypercalcemia?

Answer 31

malignancy or primary hyperparathyroidism

Question 32

Which diuretic may be useful in patients with hypercalcemia?

Answer 32

A loop diuretic, as loop diuretics increase calcium excretion in the urine. Loop diuretics should also be used in combination with hydration.

Question 33

Which diuretics should be avoided in patients with hypercalcemia?

Answer 33

thiazide diuretics, as they increase calcium reabsorption in the blood

Question 34

What are the water-permeable segments of the nephron where osmotic diuretics (like Mannitol) act?

Answer 34

PCT, descending loop of Henle, collecting ducts (if ADH present)

Question 35

Causes of diuretic resistance?

Answer 35

• NSAID co-administration
• CHF or chronic renal failure
• Nephrotic syndrome
• Hepatic cirrhosis

Question 36

Should loop and thiazide diuretics be co-administered?

Answer 36

only in patients refractory to one or the other (may be too robust and lead to K+ wasting)

Question 37

What is the best diuretic combo to prevent hypokalemia?

Answer 37

loop or thiazide diuretic plus a K+ sparing diuretic