Adverse reactions : תופעות לוואי

Adverse Reactions
Hyperkalemia side effects are considered rare when oral dosage forms of potassium are administered to patients having normal renal function. When hyperkalemia is present, symptoms include: severe muscle weakness, unusual tiredness, slow or irregular heartbeat, confusion, numbness or tingling of the hands, feet or lips, unexplained anxiety, shortness of breath or difficult breathing.

Irritation of the alimentary tract may occur when potassium passage is delayed or is in contact with ulcerous areas. Symptoms include: continuing abdominal or stomach pain, cramping, or soreness, chest or throat pain, especially when swallowing, stools containing fresh or digested blood.

The following side effects require medical attention only if they continue or are bothersome: diarrhea, nausea, stomach pain, discomfort, flatulence or mild vomiting. (These side effects occur more frequently when the medication is not taken with food or is not diluted properly.) 

Precautions
Patients must be warned not to take salt substitutes or low-salt foods, unless approved by their physician, to prevent excess intake of potassium.
Adequate renal function is essential for therapy with potassium supplements, since the kidneys maintain normal potassium balance. Monitoring of renal function, potassium serum concentrations and ECG is recommended at periodic intervals during oral therapy. The risk/benefit of potassium supplement should be considered in any patient with a higher-than- normal serum creatinine concentration.
Patients must be warned not to begin any strenuous physical exercise, if out of condition, to prevent possible exercise-induced hyperkalemia.

Drug Interactions:
Digitalis glycoside, in the presence of heart block: potassium supplements are not recommended for concurrent use in any digitalized patient with severe or complete heart block; however, if potassium supplements must be used to prevent or correct hypokalemia in a digitalized patient, careful monitoring of serum potassium concentrations is extremely important. Abrupt discontinuation of supplemental potassium to a patient suffering concurrent potassium losses, and also receiving digitalis preparations may result in digitalis toxicity.

Amphotericin B, corticosteroids especially with significant mineralocorticoid activity, corticotropin (ACTH), gentamicin, penicillins or polymyxin B: potassium requirements may be increased in patients receiving these medications due to renal potassium wasting. Close monitoring of serum potassium is recommended.

Angiotensin-converting enzyme inhibitors, beta-adrenergic blocking agents, potassium sparing diuretics, heparin, cyclosporin, non-steroidal anti-inflammatory drugs (NSAIDS): concurrent use with potassium supplements may increase serum potassium concentrations, which may cause severe hyperkalemia and lead to cardiac arrest, especially in renal insufficiency.

Thiazide diuretics: there is an increased risk of hyperkalemia when a potassium-wasting diuretic is discontinued after concurrent use with a potassium supplement.

Low-salt milk, salt substitutes, potassium-containing medications: concurrent use with potassium supplements may increase serum potassium concentrations, which may cause severe hyperkalemia and lead to cardiac arrest, especially in renal insufficiency. Most salt substitutes contain substantial amounts of potassium (low-salt milk may contain potassium up to 60 mEq/L).

Blood from blood bank: blood from blood bank may contain potassium up to 30mEq/L of plasma or up to 65 mEq/L of whole blood when stored for more than 10 days.

Parenteral calcium salts: potassium supplements should be used cautiously in patients receiving parenteral calcium salts because of the danger of precipitating cardiac arrhythmias.

Exchange resins, sodium cycle, such as sodium polystyrene sulfonate: whether these medications are administered orally or rectally, serum potassium concentrations are reduced by sodium replacement of the potassium; fluid retention may occur in some patients because of the increased sodium intake.

Insulin or sodium bicarbonate: concurrent use of these medications with potassium decreases serum potassium concentrations by promoting a shift of potassium ion into the cells.

Laxatives: chronic use or overuse of laxatives may reduce serum potassium concentrations by promoting excessive potassium loss from the intestinal tract.

Anticholinergics or other medications with anticholinergic activity: concurrent use may increase severity of gastrointestinal lesions produced by potassium chloride alone. If symptoms develop, patients should be carefully monitored endoscopically for evidence of lesions.

Dosage and Administration
Each 5 ml Potassium Oral Solution contains 10 mEq potassium.

Caution must be observed in the attempt to correct hypokalemia in order to avoid overcompensation and a resultant hyperkalemia with accompanying cardiac arrhythmias 
Adults: the usual adult and adolescent dose is 20 mEq of potassium (10 ml) diluted in 120 ml (about half a glass) of cold water or juice two to four times a day. Adjust the dose as needed and tolerated. Do not exceed 100 mEq of potassium a day.

Pediatric: the usual pediatric dose is 20-40 mEq of potassium per square meter of body surface or 2-3 mEq per kg of body weight a day, administered in divided doses and must be well diluted in water or juice.

This medication must be taken with or immediately after food, and, after dilution, should be sipped slowly.

The normal adult concentration of serum potassium is 3.5-5 mEq/L with 4.5 mEq often being used for a reference point. Potassium concentrations exceeding 5.5 mEq/L are dangerous because of possible initiation of cardiac arrhythmias. (Normal potassium concentrations tend to be higher in neonates [7.7 mEq/L] than in adults.)

Serum potassium concentrations do not necessarily indicate the true body potassium content. A rise in plasma pH (alkalosis) and chronic acidosis may decrease plasma potassium concentration by promoting potassium excretion and increase the intracellular potassium concentration. Conversely, a decrease in blood pH (acute acidosis) can cause an increase in serum potassium by inhibiting potassium excretion. However, it is necessary to attempt to restore serum potassium to normal in familial periodic paralysis, even though there is no total body potassium depletion. (It may be advisable to monitor serum pH periodically during treatment.)