Drugs for Hypokalemia and Hyperkalemia (Wolff)

Question 1

What is the normal range of potassium in the body, and what are the definitions of Hyperkalemia and Hypokalemia?

Answer 1

Normal: 3.5-5 mEq/L

Hypokalemia: < 3.7 mEq/L
Hyperkalemia: > 5.2 mEq/L

Question 2

Furosemide

What is its MOA, what pts does it work with that Thiazides do not, and what are 6 toxicities of use?

Answer 2

MOA: directly inhibits resorption of sodium/chloride in the thick ascending loop by blocking Na/K/2Cl cotransporter
- indirectly inhibits calcium and magnesium reabsorp.

• works in pts with LOW GFR, unlike thiazides

T: hypokalemia, hyponatremia, hypocalcemia, hypomagnesemia, ototoxicity, sulfonamide hypersensitivity

Question 3

Hydrochlorothiazide

What is its MOA, who is it not effective with, and what are 5 toxicities of use?

Answer 3

MOA: directly inhibits sodium resorption in distal tubules by blocking Na/Cl cotransporter

• not effective on pts. with LOW GFR

T: hypokalemia, hyponatremia, HYPERcalcemia, hypomagnesemia, sulfonamide hypersensitivity
- magnesium loss is greater than Loop Diuretic

Question 4

What are the MOAs of amiloride and spironolactone?

Answer 4

Amiloride - blocks luminal Na channels in the Collecting Duct

Spironolactone - blocks aldosterone receptor in he Collecting Duct

Question 5

Amiloride

What is its MOA, how is it administered, and what are 3 toxicities of use?

Answer 5

MOA: blocks epithelial Na channels (ENaC) in the collecting duct and helps counteract K loss induced by other diuretics in the treatment of hypertension and heart failure

• administered ORALLY

T: HYPERkalemia (boxed warning), hyponatremia, hypovolemia

Question 6

Spironolactone

What is its MOA, what is it commonly used to treat, and what are 5 toxicities of use?

Answer 6

MOA: competitive antagonist of aldosterone receptors that acts as a K-sparing diuretic, blunting promotion of Na/K exchange in collecting duct by aldosterone

• dec. basolateral Na/K ATPase
• counteracts K loss from other diuretics
• commonly used to treat primary hyperaldosteronism

T: HYPERkalemia, amenorrhea, hirsutism, gynecomastia, impotence

Question 7

When is Intravenous K given for pts. with hypokalemia and how is it administered?

Answer 7

• given to pts. with SEVERE hypokalemia (< 2.6 mEq/L) as either potassium chloride or potassium acetate
• administered at a rate of 10-20 mEq/hour

Question 8

Oral K Replacement Therapy

What should potassium be given with and why?

What are these treatments given for:

1. Potassium Chloride
2. Potassium Phosphate
3. Potassium Bicarbonate

Answer 8

• should be given with > 1/2 glass of water to help minimize/prevent GI irritation
  1. given 40-100 mg in divided doses
  2. pts with hypokalemia and hypophosphatemia
  3. pts with acidosis (can also give potassium citrate or gluconate)

Question 9

What are the 3 stages of emergency management of Hyperkalemia?

Answer 9

1. antagonize cardiac effects (give IV calcium)
2. redistribute potassium into cells
   
   • use: insulin, glucose, and B2 agonists (ALBUTEROL)
3. facilitate potassium elimination
   
   • use: K-losing diuretics, dialysis, cation xchange resin
   • mineralcorticoids (if pt has hypoaldosteronism)

continue to monitor pts. potassium intake to < 60 mEq/day