Cholestyramine

1) Cholestyramine for Oral Suspension, USP is indicated as adjunctive therapy to diet for the reduction of elevated serum cholesterol in patients with primary hypercholesterolemia (elevated low density lipoprotein [LDL] cholesterol) who do not respond adequately to diet. Cholestyramine for Oral Suspension, USP may be useful to lower LDL cholesterol in patients who also have hypertriglyceridemia, but it is not indicated where hypertriglyceridemia is the abnormality of most concern.

Therapy with lipid-altering agents should be a component of multiple risk factor intervention in those individuals at significantly increased risk for atherosclerotic vascular disease due to hypercholesterolemia. Treatment should begin and continue with dietary therapy specific for the type of hyperlipoproteinemia determined prior to initiation of drug therapy. Excess body weight may be an important factor and caloric restriction for weight normalization should be addressed prior to drug therapy in the overweight.



Prior to initiating therapy with cholestyramine resin, secondary causes of hypercholesterolemia (e.g., poorly controlled diabetes mellitus, hypothyroidism, nephrotic syndrome, dysproteinemias, obstructive liver disease, other drug therapy, alcoholism), should be excluded and a lipid profile performed to assess Total cholesterol, HDL-C and triglycerides(TG). For individuals with TG less than 400 mg/dL (<4.5mmol/L), LDL-C can be estimated using the following equation:

LDL-C = Total cholesterol - [(TG/5) + HDL-C]



For TG levels > 400 mg/dL, this equation is less accurate and LDL-C concentrations should be determined by ultracentrifugation. In hypertriglyceridemic patients, LDL-C may be low or normal despite elevated Total-C. In such cases cholestyramine resin may not be indicated.

Serum cholesterol and triglyceride levels should be determined periodically based on NCEP guidelines to confirm initial and adequate long-term response. A favorable trend in cholesterol reduction should occur during the first month of cholestyramine resin therapy. The therapy should be continued to sustain cholesterol reduction. If adequate cholesterol reduction is not attained, increasing the dosage of cholestyramine resin or adding other lipid-lowering agents in combination with cholestyramine resin should be considered.

Since the goal of treatment is to lower LDL-C, the NCEP4 recommends that LDL-C levels be used to initiate and assess treatment response. If LDL-C levels are not available then Total-C alone may be used to monitor longterm therapy. A lipoprotein analysis (including LDL-C determination) should be carried out once a year. The NCEP treatment guidelines are summarized below.

 

*Coronary heart disease or peripheral vascular disease (including symptomatic carotid artery disease).

^†Other risk factors for coronary heart disease (CHD) include: age (males ≥ 45 years; females: ≥ 55 years or premature menopause without estrogen replacement therapy); family history of premature CHD; current cigarette smoking; hypertension; confirmed HDL-C <35 mg/dL (<0.91 mmol/L); and diabetes mellitus. Subtract one risk factor if HDL-C is ≥60 mg/dL (≥1.6 mmol/L).

Cholestyramine resin monotherapy has been demonstrated to retard the rate of progression2,3 and increase the rate of regression3 of coronary atherosclerosis.

2) Cholestyramine for Oral Suspension, USP is indicated for the relief of pruritus associated with partial biliary obstruction. Cholestyramine resin has been shown to have a variable effect on serum cholesterol in these patients. Patients with primary biliary cirrhosis may exhibit an elevated cholesterol as part of their disease.

The recommended starting adult dose for Cholestyramine for Oral Suspension, USP is 1 pouch or 1 level scoopful (9 grams of Cholestyramine for Oral Suspension, USP contains 4 grams of anhydrous cholestyramine resin) once or twice a day. The recommended maintenance dose for Cholestyramine for Oral Suspension, USP 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 (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 may be administered in 1 to 6 doses per day.

The most common adverse reaction is constipation. When used as a cholesterol-lowering agent predisposing factors for most complaints of constipation are high dose and increased age (more than 60 years old). Most instances of constipation are mild, transient and controlled with conventional therapy. Some patients require a temporary decrease in dosage or discontinuation of therapy.

Less Frequent Adverse Reactions- Abdominal discomfort and/or pain, flatulence, nausea, vomiting, diarrhea, eructation, anorexia, steatorrhea, bleeding tendencies due to hypoprothrombinemia (Vitamin K deficiency) as well as Vitamin A (one case of night blindness reported) and D deficiencies, hyperchloremic acidosis in children, osteoporosis, rash and irritation of the skin, tongue and perianal area. Rare reports of intestinal obstruction, including two deaths, have been reported in pediatric patients.

Occasional calcified material has been observed in the biliary tree, including calcification of the gallbladder, in patients to whom cholestyramine resin has been given. However, this may be a manifestation of the liver disease and not drug related.

One patient experienced biliary colic on each of three occasions on which he took a cholestyramine for oral suspension product. One patient diagnosed as acute abdominal symptom complex was found to have a “pasty mass” in the transverse colon on x-ray.

Other events (not necessarily drug related) reported in patients taking cholestyramine resin include:

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 watermiscible (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.

Cholestyramine for Oral Suspension, USP the chloride salt of a basic anion exchange resin, a cholesterol lowering agent, is intended for oral administration. Cholestyramine resin is quite hydrophilic, but insoluble in water. Cholestyramine resin is not absorbed from the digestive tract. Nine grams of Cholestyramine for Oral Suspension, USP contain 4 grams of cholestyramine resin. It is represented by the following structural formula:

Figure 1

 

Representation of structure of main polymeric groups





Inactive ingredients: citric acid anhydrous, fructose, pectin, propylene glycol alginate, sorbitol, sucrose, xanthan gum, Mafco Magnasweet, orange flavor, D&C yellow No. 10 aluminum lake, FD&C yellow No. 6 aluminum lake.