Electrolyte replacement drugs Potassium

Electrolyte replacement drugs Potassium

Potassium

Potassium is the major positively charged ion (cation) in ICF. Because the body can’t store potassium, adequate amounts must be ingested daily. If this isn’t possible, potassium replacement can be accomplished orally or I.V. with potassium salts, such as:

• potassium acetate
• potassium bicarbonate
• potassium chloride
• potassium gluconate
• potassium phosphate.

Pharmacokinetics (how drugs circulate)

Oral potassium is absorbed readily from the GI tract.

Absorption, metabolism, and excretion

After absorption into the ECF, almost all of the potassium passes into the ICF. There, the enzyme adenosinetriphosphatase maintains the concentration of potassium by pumping sodium out of the cell in exchange for potassium.

Normal serum levels of potassium are maintained by the kidneys, which excrete most excess potassium intake. The rest is excreted in stool and sweat.

Pharmacodynamics (how drugs act)

Potassium moves quickly into ICF to restore depleted potassium levels and reestablish balance. It’s an essential element in determining cell membrane potential and excitability.

Feel nervous about potassium?

Potassium is necessary for proper functioning of all nerve and muscle cells and for nerve impulse transmission. It’s also essential for tissue growth and repair and for maintenance of acid-base balance.

Pharmacotherapeutics (how drugs are used)

Potassium replacement therapy corrects hypokalemia, low levels of potassium in the blood. Hypokalemia is a common occurrence in conditions that increase potassium excretion or depletion, such as:

• vomiting, diarrhea, or nasogastric suction
• excessive urination
• some kidney diseases
• cystic fibrosis
• burns
• excess of antidiuretic hormone or therapy with a potassium-depleting diuretic
• laxative abuse
• alkalosis
• insufficient potassium intake from starvation, anorexia nervosa, alcoholism, or clay ingestion
• administration of a glucocorticoid, I.V. amphotericin B, vitamin B₁₂, folic acid, granulocyte-macrophage colony’stimulating factor, or I.V. solutions that contain insufficient potassium.

Be still my heart

Potassium decreases the toxic effects of digoxin. Because potassium inhibits the excitability of the heart, normal potassium levels moderate the action of digoxin, reducing the chances of toxicity.

Drug interactions

Potassium should be used cautiously in patients receiving potassium-sparing diuretics (such as amiloride, spironolactone, and triamterene) or angiotensin-converting enzyme inhibitors (such as captopril, enalapril, and lisinopril) to avoid hyperkalemia. 

Warning!

Adverse reactions to potassium

Most adverse reactions to potassium are related to the method of administration.

Oral history

Oral potassium sometimes causes nausea, vomiting, abdominal pain, and diarrhea. Enteric-coated tablets may cause small-bowel ulceration, stenosis, hemorrhage, and obstruction.

I.V. issues

I.V. infusion of potassium preparations can cause pain at the injection site and phlebitis (vein inflammation). Given rapidly, I.V. administration may cause cardiac arrest. Infusion of potassium in patients with decreased urine production increases the risk of hyperkalemia.