WARNINGS
Hyperkalemia
(see OVERDOSAGE)
In patients with impaired mechanisms for excreting potassium, the administration of potassium salts can produce hyperkalemia and cardiac arrest. This occurs most commonly in patients given potassium intravenously, but may also occur in patients given potassium orally. Potentially fatal hyperkalemia can develop rapidly and can be asymptomatic. The use of potassium salts in patients with chronic renal disease, or any other condition which impairs potassium excretion, requires particularly careful monitoring of the serum potassium concentration and appropriate dosage adjustment.
Interaction with Potassium-Sparing Diuretics
Hypokalemia should not be treated by the concomitant administration of potassium
salts and a potassium-sparing diuretic, e.g., spironolactone, triamterene, or
amiloride, since the simultaneous administration of these agents can produce
severe hyperkalemia.
Interaction with Angiotensin Converting Enzyme Inhibitors
Angiotensin converting enzyme (ACE) inhibitors (e.g., captopril, enalapril)
will produce some potassium retention by inhibiting aldosterone production.
Potassium supplements should be given to patients receiving ACE inhibitors only
with close monitoring.
Gastrointestinal Lesions
Solid oral dosage forms of potassium chloride can produce ulcerative and/or stenotic lesions of the gastrointestinal tract. Based on spontaneous adverse reaction reports, enteric-coated preparations of potassium chloride are associated with an increased frequency of small bowel lesions (40-50 per 100,000 patient years) compared to sustained-release wax matrix formulations (less than one per 100,000 patient years). Because of the lack of extensive marketing experience with microencapsulated products, a comparison between such products and wax matrix or enteric-coated products is not available. K-TAB (potassium chloride extended-release tablets) tablets consist of a wax matrix formulated to provide a controlled rate of release potassium chloride and thus to minimize the possibility of a high local concentration of potassium near the gastrointestinal wall.
Prospective trials have been conducted in normal human volunteers in which
the upper gastrointestinal tract was evaluated by endoscopic inspection before
and after one week of solid oral potassium chloride therapy. The ability of
this model to predict events occurring in usual clinical practice is unknown.
Trials which approximated usual clinical practice did not reveal any clear differences
between the wax matrix and microencapsulated dosage forms. In contrast, there
was a higher incidence of gastric and duodenal lesions in subjects receiving
a high dose of a wax matrix controlled-release formulation under conditions
which did not resemble usual or recommended clinical practice, i.e., 96 mEq
per day in divided doses of potassium chloride administered, to fasted patients
in the presence of an anticholinergic drug to delay gastric emptying. The upper
gastrointestinal lesions observed by endoscopy were asymptomatic and were not
accompanied by evidence of bleeding (hemoccult testing). The relevance of these
findings to the usual conditions, i.e., nonfasting, no anticholinergic agent,
and smaller doses, under which controlled-release potassium chloride products
are used is uncertain. Epidemiologic studies have not identified an elevated
risk, compared to microencapsulated products, for upper gastrointestinal lesions
in patients receiving wax matrix formulations. K-TAB (potassium chloride extended-release tablets) tablets should be discontinued
immediately and the possibility of ulceration, obstruction or perforation considered
if severe vomiting, abdominal pain, distention, or gastrointestinal bleeding
occurs.
Metabolic Acidosis
Hypokalemia in patients with metabolic acidosis should be treated with an alkalinizing
potassium salt such as potassium bicarbonate, potassium citrate, potassium acetate,
or potassium gluconate.