CHENODIOL Drug Interactions: What You Need to Know

Drug Interactions Bile acid sequestering agents, such as cholestyramine and colestipol, may interfere with the action of Chenodiol by reducing its absorption. Aluminum-based antacids have been shown to absorb bile acids in vitro and may be expected to interfere with Chenodiol in the same manner as the sequestering agents. Estrogen, oral contraceptive and collaborate (and perhaps other lipid-lowering drugs) increase biliary cholesterol secretion, and the incidence of cholesterol gallstones hence may counteract the effectiveness of Chenodiol. Due to its hepatotoxicity, chenodiol can affect the pharmacodynamics of coumarin and its derivatives, causing unexpected prolongation of the prothrombin time and hemorrahages. Patients on concommitant therapy with chenodiol and coumarin or its derivatives should be monitored carefully. If prolongation of prothrombin time is observed, the coumarin dosage should be readjusted to give a prothrombin time 1½ to 2 times normal. If necessary chenodiol should be discontinued

CONTRAINDICATIONS Chenodiol is contraindicated in the presence of know hepatocyte dysfunction or bile ductal abnormalities such as intrahepatic cholestasis, primary biliary cirrhosis or sclerosing cholangitits (see Warnings); a gallbladder confirmed as nonvisualizing after two consecutive single doses of dye; radiopaque stones; or gallstone complications or compelling reasons for gallbladder surgery including unremitting acute cholecystitis, cholangitis, biliary obstruction, gallstone pancreatitis, or biliary gastrointestinal fistula.

Pregnancy

Category X: Chenodiol may cause fetal harm when administered to a pregnant woman. Serious hepatic, renal and adrenal lesions occurred in fetuses of female Rhesus monkeys given 60 to 90 mg/kg/day (4 to 6 times the maximum recommended human dose, MRHD) from day 21 to day 45 of pregnancy. Hepatic lesions also occurred in neonatal baboons whose mothers had received 18 to 38 mg/kg ( 1 to 2 times the MRHD), all during pregnancy. Fetal malformations were not observed. Neither fetal liver damage nor fetal abnormalities occurred in reproduction studies in rats and hamsters. No human data are available at this time. Chenodiol is contraindicated in women who are or may become pregnant. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to the fetus.

WARNINGS Safe use of chenodiol depends upon selection of patients without pre-existing liver disease and upon faithful monitoring of serum aminotransferase levels to detect drug-induced liver toxicity. Aminotransferase elevations over three times the upper limit of normal have required discontinuation of chenodiol in 2% to 3% of patients. Although clinical and biopsy studies have not shown fulminant lesions, the possibility remains that an occasional patient may develop serious hepatic disease. Three patients with biochemical and histologic pictures of chronic active hepatitis while on chenodiol, 375 mg/day or 750 mg/day, have been reported. The biochemical abnormalities returned spontaneously to normal in two of the patients within 13 and 17 months; and after 17 months’ treatment with prednisone in the third. Follow-up biopsies were not done; and the causal relationship of the drug could not be determined. Another biopsied patient was terminated from therapy because of elevated aminotransferase levels and a liver biopsy was interpreted as showing active drug hepatitis. One patient with sclerosing cholangitis, biliary cirrhosis and history of jaundice died during chenodiol treatment for hepatic duct stones. Before treatment, serum aminotransferase and alkaline phosphate levels were over twice the upper limit of normal; within one month they rose to over 10 time normal. Chenodiol was discontinued at seven weeks, when the patient was hospitalized with advanced hepatic failure and E. coli peritonitis; death ensued at the eight week. A contribution of chenodiol to the fatal outcome could not be ruled out. Epidemiologic studies suggest that bile acids might contribute to human colon cancer, but direct evidence is lacking. Bile acids, including chenodiol and lithocholic acid, have no carcinogenic potential in animal models, but have been shown to increase the number of tumors when administered with certain know carcinogens. The possibility that chenodiol therapy might contribute to colon cancer in otherwise susceptible individuals cannot be ruled out.