DOSAGE & ADMINISTRATION SECTION

DOSAGE AND ADMINISTRATION

The recommended starting adult dose for Cholestyramine for Oral Suspension, USP Light powder is one pouch or one level scoopful (5.7 grams of Cholestyramine for Oral Suspension, USP Light powder contains 4 grams of anhydrous cholestyramine resin) once or twice a day. The recommended maintenance dose for Cholestyramine for Oral Suspension, USP Light powder is 2 to 4 pouches or scoopfuls daily (8 to 16 grams anhydrous cholestyramine resin) divided into two doses. It is recommended that increases in dose be gradual with periodic assessment of lipid/lipoprotein levels at intervals of not less than 4 weeks. The maximum recommended daily dose is 6 pouches or scoopfuls of Cholestyramine for Oral Suspension, USP Light powder (24 grams of anhydrous cholestyramine resin). The suggested time of administration is at mealtime but may be modified to avoid interference with absorption of other medications. Although the recommended dosing schedule is twice daily, Cholestyramine for Oral Suspension, USP Light powder may be administered in 1 to 6 doses per day.

Cholestyramine for Oral Suspension, USP Light powder should not be taken in its dry form. Always mix the dry powder with water or other fluids before ingesting. See Preparation Instructions.

Concomitant Therapy

Preliminary evidence suggests that the lipid-lowering effects of cholestyramine on total and LDL-cholesterol are enhanced when combined with a HMG-COA reductase inhibitor, e.g., pravastatin, lovastatin, simvastatin and fluvastatin. Additive effects on LDL-cholesterol are also seen with combined nicotinic acid/cholestyramine therapy. See the PRECAUTIONS, Drug Interactions for recommendations on administering concomitant therapy.

Preparation

The color of Cholestyramine for Oral Suspension, USP Light powder may vary somewhat from batch to batch but this variation does not affect the performance of the product. Place the contents of one single-dose pouch or one level scoopful of Cholestyramine for Oral Suspension, USP Light powder in a glass or cup. Add at least 2 to 3 ounces of water or the beverage of your choice. Stir to a uniform consistency.

Cholestyramine for Oral Suspension, USP Light powder may also be mixed with highly fluid soups or pulpy fruits with a high moisture content such as applesauce or crushed pineapple.

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PRECAUTIONS SECTION

PRECAUTIONS

General

Chronic use of cholestyramine resin may be associated with increased bleeding tendency due to hypoprothrombinemia associated with Vitamin K deficiency. This will usually respond promptly to parenteral Vitamin K1 and recurrences can be prevented by oral administration of Vitamin K1. Reduction of serum or red cell folate has been reported over long term administration of cholestyramine resin. Supplementation with folic acid should be considered in these cases.

There is a possibility that prolonged use of cholestyramine resin, since it is a chloride form of anion exchange resin, may produce hyperchloremic acidosis. This would especially be true in younger and smaller patients where the relative dosage may be higher. Caution should also be exercised in patients with renal insufficiency or volume depletion and in patients receiving concomitant spironolactone. Cholestyramine resin may produce or worsen preexisting constipation. The dosage should be increased gradually in patients to minimize the risk of developing fecal impaction. In patients with preexisting constipation, the starting dose should be 1 pouch or 1 scoop once daily for 5 to 7 days, increasing to twice daily with monitoring of constipation and of serum lipoproteins, at least twice, 4 to 6 weeks apart. Increased fluid intake and fiber intake should be encouraged to alleviate constipation and a stool softener may occasionally be indicated. If the initial dose is well tolerated, the dose may be increased as needed by one dose/day (at monthly intervals) with periodic monitoring of serum lipoproteins. If constipation worsens or the desired therapeutic response is not achieved at one to six doses/day, combination therapy or alternate therapy should be considered. Particular effort should be made to avoid constipation in patients with symptomatic coronary artery disease. Constipation associated with cholestyramine resin may aggravate hemorrhoids.

Information for Patients

Inform your physician if you are pregnant or plan to become pregnant or are breast-feeding. Drink plenty of fluids and mix each 5.7 gram dose of Cholestyramine for Oral Suspension USP Light powder in at least 2 to 3 ounces of fluid before taking. Sipping or holding the resin suspension in the mouth for prolonged periods may lead to changes in the surface of the teeth resulting in discoloration, erosion of enamel or decay; good oral hygiene should be maintained.

Laboratory Tests

Serum cholesterol levels should be determined frequently during the first few months of therapy and periodically thereafter. Serum triglyceride levels should be measured periodically to detect whether significant changes have occurred.

The LRC-CPPT showed a dose-related increase in serum triglycerides of 10.7% to 17.1% in the cholestyramine-treated group, compared with an increase of 7.9% to 11.7% in the placebo group. Based on the mean values and adjusting for the placebo group, the cholestyramine-treated group showed an increase of 5% over pre-entry levels the first year of the study and an increase of 4.3% the seventh year.

Drug Interactions

Cholestyramine resin may delay or reduce the absorption of concomitant oral medication such as phenylbutazone, warfarin, thiazide diuretics (acidic) or propranolol (basic), as well as tetracycline, penicillin G, phenobarbital, thyroid and thyroxine preparations, estrogens and progestins and digitalis. Interference with the absorption of oral phosphate supplements has been observed with another positivelycharged bile acid sequestrant. Cholestyramine resin may interfere with the pharmacokinetics of drugs that undergo enterohepatic circulation. The discontinuance of cholestyramine resin could pose a hazard to health if a potentially toxic drug such as digitalis has been titrated to a maintenance level while the patient was taking cholestyramine resin.

Because cholestyramine binds bile acids, cholestyramine resin may interfere with normal fat digestion and absorption and thus may prevent absorption of fat-soluble vitamins such as A, D, E and K. When cholestyramine resin is given for long periods of time, concomitant supplementation with water-miscible (or parenteral) forms of fat soluble vitamins should be considered.

SINCE CHOLESTYRAMINE RESIN MAY BIND OTHER DRUGS GIVEN CONCURRENTLY, IT IS RECOMMENDED THAT PATIENTS TAKE OTHER DRUGS AT LEAST 1 HOUR BEFORE OR 4 TO 6 HOURS AFTER CHOLESTYRAMINE RESIN (OR AT AS GREAT AN INTERVAL AS POSSIBLE) TO AVOID IMPEDING THEIR ABSORPTION.

Carcinogenesis, Mutagenesis, Impairment of Fertility

In studies conducted in rats in which cholestyramine resin was used as a tool to investigate the role of various intestinal factors, such as fat, bile salts and microbial flora, in the development of intestinal tumors induced by potent carcinogens, the incidence of such tumors was observed to be greater in cholestyramine resin-treated rats than in control rats.

The relevance of this laboratory observation from studies in rats to the clinical use of cholestyramine resin is not known. In the LRCCPPT study referred to above, the total incidence of fatal and nonfatal neoplasms was similar in both treatment groups. When the many different categories of tumors are examined, various alimentary system cancers were somewhat more prevalent in the cholestyramine group. The small numbers and the multiple categories prevent conclusions from being drawn. However, in view of the fact that cholestyramine resin is confined to the GI tract and not absorbed and in light of the animal experiments referred to above, a six-year post-trial follow-up of the LRC-CPPT5 patient population has been completed (a total of 13.4 years of in-trial plus post-trial follow-up) and revealed no significant difference in the incidence of cause-specific mortality or cancer morbidity between cholestyramine and placebo treated patients.

Pregnancy

Pregnancy Category C

There are no adequate and well controlled studies in pregnant women. The use of cholestyramine in pregnancy or lactation or by women of childbearing age requires that the potential benefits of drug therapy be weighted against the possible hazards to the mother and child. Cholestyramine is not absorbed systemically, however, it is known to interfere with absorption of fat-soluble vitamins; accordingly, regular prenatal supplementation may not be adequate (see PRECAUTIONS, Drug Interactions).

Nursing Mothers

Caution should be exercised when cholestyramine resin is administered to a nursing mother. The possible lack of proper vitamin absorption described in PRECAUTIONS, Pregnancy may have an effect on nursing infants.

Pediatric Use

Although an optimal dosage schedule has not been established, standard texts(6,7) list a usual pediatric dose of 240 mg/kg/day of anhydrous cholestyramine resin in two to three divided doses, normally not to exceed 8 g/day with dose titration based on response and tolerance.

In calculating pediatric dosages, 70.2 mg of anhydrous cholestyramine resin are contained in 100 mg of Cholestyramine for Oral Suspension USP Light.

The effects of long-term drug administration, as well as its effect in maintaining lowered cholesterol levels in pediatric patients, are unknown. Also see ADVERSE REACTIONS.

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