Drugs for Hypo/Hyperkalemia Flashcards
What defines Hyperkalemia?
Plasma [K+] > 5.2
What defines Hypokalemia?
Plasma [K+] < 3.7
Is K+ usually inside or outside of the cell?
Inside
If K+ is outside of the cell, then it will be?
Hyperkalemia
What things cause K+ to go inside the cell, thus causing more hypokalemic actions?
Insulin
Beta2 Agonists
Alpha Antagonists
Aldosterone deficiency
What classes of drugs are K+ sparing diuretics?
Aldosterone Antagonists
Na+ channel blockers
Where do K+ sparing diuretics act?
Cortical Collecting Duct
What classes of drugs are K+ losing diuretics?
Loops
Thiazides
Carbonic Anhydrase (-)’s
Osmotic diuretics
MOA for Thiazides and where do they act?
Block Na+ Cl- channels
– act at distal convoluted tubule
MOA for Loops and where do they act?
Block Na+ K+ 2Cl- channels
– act at thick ascending limb
Carbonic Anhydrase (-)’s and Osmotic Diuretics are used less often, but where do they act?
Proximal tubule and thin descending limb
What are 2 reasons to give Diuretics?
HTN
Edema due to heart/kidney/liver failure
What are the 4 loops?
Furosemide
Torsemide
Bumetanide
Ethacrynic Acid
Loops work in patients with _____ unlike Thiazides
Low GFR
Loops and Thiazides should not be used in patients with an allergy to?
Sulfa
Which Loop can be used in patients with a sulfa allergy?
Ethacrynic Acid
What is a possible side effect of Furosemide?
Ototoxicity
Which loop has a longer half life, better oral absorption and works better in HF?
Torsemide
Which loop has more predictable oral absorption?
Bumetanide
What are the 4 Thiazides?
HCTZ
Chlorothiazide
Chlorthalidone
Metolazone
Which Thiazide has poor oral absorption?
Chlorothiazide
Which Thiazide has a half life of 40-60 hours and is preferred by some HTN specialists?
Chlorthalidone
Which Thiazide is preferred with CHF?
Metolazone
Why do Thiazides cause Hypercalcemia?
More reabsorption in proximal tubule due to volume contraction
Between loops and thiazides, which cause more Magnesium loss?
Thiazides
What are the Na+ channel blockers?
Triamterene
Amiloride
What are the Aldosterone Antagonists?
Spironolactone
Eplerenone
What is a possible side effect of the K+ sparing diuretics?
(Na+ channel blockers and Aldosterone antagonists)
= Hyperkalemia
Spironolactone is also a ____ which can cause?
Partial agonist at androgen receptors
=> Amenorrhea, Hirsutism, Gynecomastia
What can Spironolactone decrease with post-MI heart failure?
Decreases Fibrosis on the heart
Which Aldosterone Antagonist is more selective?
Eplerenone
What are the symptoms of Hypokalemia?
Lethargic, Lots of urine output, arrhythmias, cramps, low BP
What is the treatment for Hypokalemia?
K+ replacement
IV K+ replacement is used with severe Hypokalemia. What kind is used and how fast?
K+ chloride/acetate – 10-20 mEq/hr
Oral K+ replacement should be taken with water to prevent?
GI irritation
What are the symptoms of Hyperkalemia?
Bradycardia, low urine output, numb, weak, paralysis
What are the ECG changes with Hyperkalemia?
Peaked T wave and Widened QRS
What are the 3 steps to treating Hyperkalemia?
- Antagonist cardiac effects
- Redistribute K+ into cells
- Facilitate K+ loss
With Hyperkalemia, how do you antagonist cardiac effects?
Give IV calcium
With Hyperkalemia, how do you redistribute K+ into the cells?
Give Insulin, Glucose or Beta2 agonists
With Hyperkalemia, how do you facilitate K+ loss?
Give K+ losing diuretics, mineralcorticoids or dialysis
If there is Acidosis, what is the level of K+ usually?
Hyperkalemia
