WARNINGS
PHENYLKETONURICS: PREVALITE®
CONTAINS 14.1 mg PHENYLALANINE PER 5.5 GRAM DOSE.
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 pre-existing constipation. The dosage should be increased
gradually in patients to minimize the risk of developing fecal impaction. In
patients with pre-existing constipation, the starting dose should be 1 packet
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.
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.
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 LRC-CPPT 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 the “Pregnancy” section may have
an effect on nursing infants.
Pediatric Use
Although an optimal dosage
schedule has not been established, standard texts6,7 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, 80 mg of anhydrous cholestyramine resin are contained in 110 mg of
Prevalite®.
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.
REFERENCES
5. The Lipid Research Clinics
Investigators. The Lipid Research Clinics Coronary Primary Prevention Trial
Results of 6 Years of Post-Trial Follow-up. Arch Intern Med 1992; 152:
1399-1410.
6. Behrman RE et al (eds):
Nelson, Textbook of Pediatrics, ed 15. Philadelphia, PA, WB Saunders Company,
1996.
7. Takemoto CK et al (eds): Pediatric
Dosage Handbook, ed 3. Cleveland/Akron, OH, Lexi-Comp, Inc., 1996/1997.