Sodium Polystyrene Sulfonate

SODIUM POLYSTYRENE SULFONATE- sodium polystyrene sulfonate suspension
CMP Pharma, Inc.

CMP Pharma, Inc.
Cation-Exchange Resin
Rx Only

DESCRIPTION

Sodium Polystyrene Sulfonate Suspension USP (SPS^® Suspension) can be administered orally or in an enema. It is a cherry-flavored suspension containing 15 grams of cation-exchange resin (Sodium Polystyrene Sulfonate USP); 21.5 mL of Sorbitol Solution USP (equivalent to approximately 20 grams of Sorbitol) ; 0.18 mL (0.3%) of Alcohol per 60 mL of suspension. Also contains Purified Water USP; Propylene Glycol USP; Magnesium Aluminum Silicate NF; Sodium Saccharin USP; Methylparaben NF; Propylparaben NF; and flavor.

Sodium polystyrene sulfonate is a benzene, diethenyl-, polymer with ethenylbenzene, sulfonated, sodium salt and has the following structural formula:

The sodium content of the suspension is 1500 mg (65 mEq) per 60 mL. It is a brown, slightly viscous suspension with an in‑vitro exchange capacity of approximately 3.1 mEq (in-vivo approximately 1 mEq) of potassium per 4 mL (1 gram) of suspension. It can be administered orally or in an enema.

CLINICAL PHARMACOLOGY

As the resin passes along the intestine or is retained in the colon after administration by enema, the sodium ions are partially released and are replaced by potassium ions. For the most part, this action occurs in the large intestine, which excretes potassium ions to a greater degree than does the small intestine. The efficiency of this process is limited and unpredictably variable. It commonly approximates the order of 33%, but the range is so large that definitive indices of electrolyte balance must be clearly monitored.

Metabolic data are unavailable.

INDICATION AND USAGE

SPS^® Suspension is indicated for the treatment of hyperkalemia.

CONTRAINDICATIONS

SPS^® Suspension is contraindicated in the following conditions: patients with hypokalemia, patients with a history of hypersensitivity to polystyrene sulfonate resins, obstructive bowel disease, oral or rectal administration in neonates (See PRECAUTIONS).

WARNINGS

Intestinal Necrosis

Cases of intestinal necrosis, which may be fatal, and other serious gastrointestinal adverse events (bleeding, ischemic colitis, perforation) have been reported in association with sodium polystyrene sulfonate use. The majority of these cases reported the concomitant use of sorbitol. Risk factors for gastrointestinal adverse events were present in many of the cases including prematurity, history of intestinal disease or surgery, hypovolemia, and renal insufficiency and failure. Concomitant administration of additional sorbitol is not recommended (see PRECAUTIONS, Drug Interactions).

• Use only in patients who have normal bowel function. Avoid use in patients who have not had a bowel movement post-surgery.
• Avoid use in patients who are at risk for developing constipation or impaction (including those with history of impaction, chronic constipation, inflammatory bowel disease, ischemic colitis, vascular intestinal atherosclerosis, previous bowel resection, or bowel obstruction).
• Discontinue use in patients who develop constipation.

Alternative Therapy in Severe Hyperkalemia

Since the effective lowering of serum potassium with sodium polystyrene sulfonate may take hours to days, treatment with this drug alone may be insufficient to rapidly correct severe hyperkalemia associated with states of rapid tissue breakdown (e.g., burns and renal failure) or hyperkalemia so marked as to constitute a medical emergency. Therefore, other definitive measures, including dialysis, should always be considered and may be imperative.

Hypokalemia

Serious potassium deficiency can occur from sodium polystyrene sulfonate therapy. The effect must be carefully controlled by frequent serum potassium determinations within each 24 hour period. Since intracellular potassium deficiency is not always reflected by serum potassium levels, the level at which treatment with sodium polystyrene sulfonate should be discontinued must be determined individually for each patient. Important aids in making this determination are the patient’s clinical condition and electrocardiogram. Early clinical signs of severe hypokalemia include a pattern of irritable confusion and delayed thought processes.

Electrocardiographically, severe hypokalemia is often associated with a lengthened Q-T interval, widening, flattening, or inversion of the T wave, and prominent U waves. Also, cardiac arrhythmias may occur, such as premature atrial, nodal, and ventricular contractions, and supraventricular and ventricular tachycardias. The toxic effects of digitalis are likely to be exaggerated. Marked hypokalemia can also be manifested by severe muscle weakness, at times extending into frank paralysis.

Electrolyte Disturbances

Like all cation-exchange resins, sodium polystyrene sulfonate is not totally selective (for potassium) in its actions, and small amounts of other cations such as magnesium and calcium can also be lost during treatment. Accordingly, patients receiving sodium polystyrene sulfonate should be monitored for all applicable electrolyte disturbances.

Systemic Alkalosis

Systemic alkalosis has been reported after cation-exchange resins were administered orally in combination with nonabsorbable cation-donating antacids and laxatives such as magnesium hydroxide and aluminum carbonate. Magnesium hydroxide should not be administered with sodium polystyrene sulfonate. One case of grand mal seizure has been reported in a patient with chronic hypocalcemia of renal failure who was given sodium polystyrene sulfonate with magnesium hydroxide as a laxative (See PRECAUTIONS, Drug Interactions).

Risk of Aspiration

Cases of acute bronchitis or bronchopneumonia caused by inhalation of sodium polystyrene sulfonate particles has been reported. Patients with impaired gag reflex, altered level of consciousness, or patients prone to regurgitation may be at increased risk. Administer sodium polystyrene sulfonate suspension with the patient in an upright position.

Binding to Other Orally Administered Medications

Sodium polystyrene sulfonate suspension may bind orally administered medications, which could decrease their gastrointestinal absorption and lead to reduced efficacy. Administer other oral medications at least 3 hours before or 3 hours after sodium polystyrene sulfonate suspension. Patients with gastroparesis may require a 6 hour separation (see DOSAGE AND ADMINISTRATION and PRECAUTIONS, Drug Interactions).

PRECAUTIONS

Caution is advised when sodium polystyrene sulfonate is administered to patients who cannot tolerate even a small increase in sodium loads (i.e., severe congestive heart failure, severe hypertension, or marked edema). In such instances compensatory restriction of sodium intake from other sources may be indicated.

Precautions should be taken to ensure the use of adequate volumes of sodium-free cleansing enemas after rectal administration.

In the event of clinically significant constipation, treatment with SPS^® Suspension should be discontinued until normal bowel motion is resumed (See WARNINGS, Intestinal Necrosis).

Drug Interactions

General Interactions

No formal drug interaction studies have been conducted in humans.
Sodium polystyrene sulfonate suspension has the potential to bind other drugs. In in-vitro binding studies, sodium polystyrene sulfonate was shown to significantly bind the oral medications (n=6) that were tested. Decreased absorption of lithium and thyroxine have also been reported with co-administration of sodium polystyrene sulfonate. Binding of sodium polystyrene sulfonate suspension to other oral medications could cause decreased gastrointestinal absorption and loss of efficacy when taken close to the time sodium polystyrene sulfonate suspension is administered. Administer sodium polystyrene sulfonate suspension at least 3 hours before or 3 hours after other oral medications. Patients with gastroparesis may require a 6 hour separation. Monitor for clinical response and/or blood levels where possible.