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 by
the intravenous route but may also occur in patients given potassium orally.
Potentially fatal hyperkalemia can develop rapidly and 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 (eg, 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 (eg, 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.
Potassium Chloride is a tablet formulated to provide a controlled rate of release
of microencapsulated 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 1 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 (ie, 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 (ie, non-fasting, no anticholinergic agent,
smaller doses) under which controlled-release potassium chloride products are
used is uncertain; epidemiologic studies have not identified an elevated risk,
compared to micro-encapsulated products, for upper gastrointestinal lesions
in patients receiving wax matrix formulations. Potassium Chloride Extended Release
Tablets should be discontinued immediately and the possibility of ulceration,
obstruction, or perforation should be 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.