CHOLESTYRAMINE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for CHOLESTYRAMINE (CHOLESTYRAMINE).
Cholestyramine is a bile acid sequestrant that binds bile acids in the intestine, forming an insoluble complex that is excreted in feces. This reduces enterohepatic circulation of bile acids, leading to increased conversion of cholesterol to bile acids in the liver and decreased serum low-density lipoprotein (LDL) cholesterol levels.
| Metabolism | Cholestyramine is not absorbed systemically; it acts locally in the gastrointestinal tract and is excreted unchanged in feces. |
| Excretion | Cholestyramine is not absorbed systemically; it remains in the gastrointestinal tract and is excreted unchanged in feces. No renal or biliary elimination occurs. |
| Half-life | Not applicable; cholestyramine is not absorbed and does not have a systemic half-life. Its clinical effect is related to gastrointestinal transit time. |
| Protein binding | Not applicable; cholestyramine is not absorbed and does not bind to plasma proteins. |
| Volume of Distribution | Not applicable; due to lack of systemic absorption, Vd is essentially zero. |
| Bioavailability | Oral: <0.1% (negligible systemic absorption); cholestyramine acts locally in the gastrointestinal tract. |
| Onset of Action | Oral: Onset of lipid-lowering effect is typically within 24-48 hours, with maximal effect on LDL cholesterol seen after 4-6 weeks of continuous therapy. |
| Duration of Action | Duration of action is dependent on dosing schedule; effects persist as long as the drug is present in the gut. After discontinuation, effects wane over several days. |
4 g orally once or twice daily, titrated up to 24 g/day divided into 2-6 doses; usual maintenance dose 8-16 g/day
| Dosage form | POWDER |
| Renal impairment | No dosage adjustment required for renal impairment; caution in patients with severe renal disease due to risk of hyperchloremic metabolic acidosis |
| Liver impairment | Use with caution in cirrhosis or cholestatic disorders; no specific Child-Pugh guidelines; monitor for increased bleeding risk due to vitamin K malabsorption |
| Pediatric use | Initial 240 mg/kg/day (approximately 0.625 g/kg/day) divided into 2-3 doses, titrated based on response; maximum 8 g/day |
| Geriatric use | Start at low end of dosing range (4 g/day) due to increased risk of constipation and fecal impaction; monitor for electrolyte disturbances and drug interactions |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for CHOLESTYRAMINE (CHOLESTYRAMINE).
| Breastfeeding | Cholestyramine is not excreted into breast milk due to negligible systemic absorption. It is considered compatible with breastfeeding, as no adverse effects on the nursing infant have been reported. M/P ratio is not applicable. Monitor infant for signs of vitamin deficiency if mother uses high doses long-term. |
| Teratogenic Risk | Cholestyramine is not absorbed systemically; therefore, direct fetal exposure is negligible. No teratogenic effects have been reported in animal studies or human case reports. However, due to potential maternal fat-soluble vitamin deficiency (A, D, E, K) caused by the drug, indirect fetal risk exists, especially in the first trimester for neural tube defects (vitamin A) and second/third trimester for coagulation (vitamin K). Use only if clearly needed and monitor maternal vitamin levels. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["Complete biliary obstruction (unable to excrete bile into intestine)","Hypersensitivity to cholestyramine or any component","Phenylketonuria (if product contains aspartame)"]
| Precautions | ["May reduce absorption of fat-soluble vitamins (A, D, E, K) and folic acid; supplementation may be required.","May impair absorption of other medications (e.g., digoxin, warfarin, thyroid hormones); administer at least 4-6 hours before or after cholestyramine.","May cause hyperchloremic metabolic acidosis, especially in pediatric patients.","May exacerbate hemorrhoids due to constipation.","Use with caution in patients with phenylketonuria (contains aspartame in some formulations)."] |
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| Fetal Monitoring | Monitor maternal serum levels of fat-soluble vitamins (A, D, E, K) and prothrombin time (INR) periodically. During pregnancy, assess fetal growth and development via ultrasound. In the third trimester, monitor for signs of maternal coagulopathy. Postpartum, monitor infant for bleeding or vitamin deficiency if supplementation was inadequate. |
| Fertility Effects | No direct effects on fertility in males or females due to lack of systemic absorption. However, chronic use may lead to vitamin deficiencies (especially vitamin D and E) that could theoretically affect reproductive function, though no clinical evidence supports this. In polycystic ovary syndrome, cholestyramine may improve fertility by reducing bile acid levels, but this is not a standard indication. |