CLINICAL PHARMACOLOGY
The potassiumion is the principal intracellular cation
of most body tissues. Potassium ions participate in a number of essential
physiological processes including the maintenance of intracellular tonicity,
the transmission of nerve impulses, the contraction of cardiac, skeletal and
smooth muscle and the maintenance of normal renal function.
The intracellular concentration of potassium is
approximately 150 to 160 mEq per liter. The normal adult plasma concentration
is 3.5 to 5 mEq per liter. An active ion transport system maintains this
gradient across the plasma membrane.
Potassium is a normal dietary constituent and under
steady state conditions the amount of potassium absorbed from the
gastrointestinal tract is equal to the amount excreted in the urine. The usual
dietary intake of potassium is 50 to 100 mEq per day.
Potassium depletion will occur whenever the rate of
potassium loss through renal excretion and/or loss from the gastrointestinal
tract exceeds the rate of potassium intake. Such depletion usually develops slowly
as a consequence of prolonged therapy with oral diuretics, primary or secondary
hyperaldosteronism, diabetic ketoacidosis, severe diarrhea, or inadequate
replacement of potassium in patients on prolonged parenteral nutrition.
Depletion can develop rapidly with severe diarrhea, especially if associated
with vomiting. Potassium depletion due to these causes is usually accompanied by
a concomitant loss of chloride and is manifested by hypokalemia and metabolic
alkalosis. Potassium depletion may produce weakness, fatigue, disturbances of
cardiac rhythm (primarily ectopic beats), prominent U-waves in the
electrocardiogram and, in advanced cases, flaccid paralysis and/or impaired ability
to concentrate urine.
If potassium depletion associated with metabolic
alkalosis cannot be managed by correcting the fundamental cause of the
deficiency, e.g., where the patient requires long term diuretic therapy, supplemental
potassium in the form of high potassium food or potassium chloride may be able
to restore normal potassium levels.
In rare circumstances (e.g., patients with renal tubular
acidosis) potassium depletion may be associated with metabolic acidosis and
hyperchloremia. In such patients potassium replacement should be accomplished
with potassium salts other than the chloride, such as potassium bicarbonate,
potassium citrate, potassium acetate or potassium gluconate.
The potassium chloride in Klor-Con® Extended-release
Tablets is completely absorbed before it leaves the small intestine. The wax matrix
is not absorbed and is excreted in the feces; in some instances the empty
matrices may be noticeable in the stool. When the bioavailability of the
potassium ion from the Klor-Con® Extended-release Tablets is compared to that
of a true solution the extent of absorption is similar.
The extended-release properties of Klor-Con®
Extended-release Tablets are demonstrated by the finding that a significant
increase in time is required for renal excretion of the first 50% of the Klor-Con®
Extended-release Tablets dose as compared to the solution.
Increased urinary potassium excretion is first observed 1
hour after administration of Klor-Con® Extended-release Tablets, reaches a peak
at approximately 4 hours, and extends up to 8 hours. Mean daily steady-state
plasma levels of potassium following daily administration of Klor-Con®
Extendedrelease Tablets cannot be distinguished from those following
administration of potassium chloride solution or from control plasma levels of
potassium ion.