Chenodal 250 mg (chenodiol tablets)
PACKAGE LABEL.PRINCIPAL DISPLAY PANEL
Rx onlyNDC 45043-876-40Chenodal 250 mg(Chenodiol Tablets)100 TabletsManchester Pharmaceuticals, Inc.Each Film-Coated Tablet Contains: Chenodiol 250 mg Usual Adult Dosage: Please see package insert for detailed prescribing information. Store and Dispense: Store at 200 to 250C (680 to 770F). [see USP Controlled Room Temperature]. Dispense in a tight container as defined in the USP. KEEP THIS AND ALL MEDICATION OUT OF THE REACH OF CHILDREN. Manufactured for: Manchester Pharmaceuticals, Inc. Fort Collins, CO 80525 866-758-7068Bar code45043 87640Lot No.:Exp. Date:
SPECIAL NOTE
DESCRIPTION
Chenodiol is the non-proprietary name for chenodeoxycholic acid, a naturally occurring human bile acid. It is a bitter-tasting white powder consisting of crystalline and amorphous particles freely soluble in methanol, acetone and acetic acid and practically insoluble in water. Its chemical name is 3α, 7α-dihydroxy-5β-cholan-24-oic acid (C24H40O4), it has a molecular weight of 392.58, and its structure is shown below;Chenodiol film-coated tablets for oral administration contain 250 mg of chenodiol.Inactive ingredients: pregelatinized starch; silicon dioxide; microcrystalline cellulose, sodium starch glycollate; and magnesium stearate; the thin-film coating contains: opadry YS-2-7035 [consisting of methylcellulose and glycerin] and sodium lauryl sulfate
CLINICAL PHARMACOLOGY
At therapeutic doses, chenodiol suppresses hepatic synthesis of both cholesterol and cholic acid, gradually replacing the latter and its metabolite, deoxycholic acid in an expanded bile acid pool. These actions contribute to biliary cholesterol desaturation and gradual dissolution of radiolucent cholesterol gallstones in the presence of a gall-bladder visualized by oral cholecystography. Chenodiol has no effect on radiopaque (calcified) gallstones or on radiolucent bile pigment stones.Chenodiol is well absorbed from the small intestine and taken up by the liver where it is converted to its taurine and glycine conjugates and secreted in bile. Owing to 60 % to 80% first-pass hepatic clearance, the body pool of chenodiol resides mainly in the enterohepatic circulation; serum and urinary bile acid levels are not significantly affected during chenodiol therapy.At steady-state, an amount of chenodiol near the daily dose escapes to the colon and is converted by bacterial action to lithocholic acid. About 80% of the lithocholate is excreted in the feces; the remainder is absorbed and converted in the liver to its poorly absorbed sulfolithocholyl conjugates. During chenodiol therapy there is only a minor increase in biliary lithocholate, while fecal bile acids are increased three- to fourfold.Chenodiol is unequivocally hepatotoxic in many animal species, including sub-human primates at doses close to the human dose. Although the theoretical cause is the metabolite, lithocholic acid, an established hepatotoxin, and man has an efficient mechanism for sulfating and eliminating this substance, there is some evidence that the demonstrated hepatotoxicity is partly due to chenodiol per se. The hepatotoxicity of lithocholic acid is characterized biochemically and morphologically as cholestatic.Man has the capacity to form sulfate conjugates of lithocholic acid. Variation in this capacity among individuals has not been well established and a recent published report suggests that patients who develop chenodiol-induced serum aminotransferase elevations are poor sulfators of lithocholic acid (see ADVERSE REACTIONS and WARNINGS).
General Clinical Results
Floatable versus Nonfloatable Stones
A major finding in clinical trials was a difference between floatable and nonfloatable stones, with respect to both natural history and response to chenodiol. Over the two-year course of the National Cooperative Gallstone Study (NCGS), placebo – treated patients with floatable stones (n = 47) had significantly higher rates of biliary pain and cholecystectomy than patients with nonfloatable stones (n = 258) (47% versus 27% and 19%versus 4%, respectively). Chenodiol treatment (750 mg/day) compared to placebo was associated with a significant reduction in both biliary pain and the cholecystectomy rates in the group with floatable stones (27% versus 47% and 1.5% versus 19%, respectively). In an uncontrolled clinical trial using 15 mg/kg/day, 70% of the patients with small (less than 15 mm) floatable stones (n = 10) had complete confirmed dissolution.In the NCGS in patients with nonfloatable stones, chenodiol produced no reduction in biliary pain and showed a tendency to increase the cholecystectomy rate (8% versus 4%). This finding was more pronounced with doses of chenodiol below 10 mg/kg. The subgroup of patients with nonfloatable stones and a history of biliary pain had the highest rates of cholecystectomy and aminotransferase elevations during chenodiol treatment. Except for the NCGS subgroup with pretreatment biliary pain, dose-related aminotransferase elevations and diarrhea have occurred with equal frequency in patients with floatable or nonfloatable stones. In the uncontrolled clinical trial mentioned above, 27% of the patients with nonfloatable stones (n = 59) had complete confirmed dissolutions, including 35% with small (less than 15 mm)(n= 40) and only 11% with large, nonfloatable stones (n= 19).Of 916 patients enrolled NCGS, 17.6% had stones seen in upright form (horizontal X-ray beam) to float in the dye-laden bile during oral cholecystography using iopanoic acid. Other investigators report similar findings. Floatable stones are not detected by ultrasonography in the absence for dye. Chemical analysis has shown floatable stones to be essentially pure cholesterol).
Other Radiographic and Laboratory Features
Radiolucent stones may have rims or centers of opacity representing calcification. Pigment stones and partially calcified radiolucent stones do not respond to chenodiol. Subtle calcification can sometimes be detected in flat film X-rays, if not obvious in the oral cholecystogram. Among nonfloatable stones, cholesterol stones are more apt than pigment stones to be smooth surfaced, less than 0.5 cm in diameter, and to occur in numbers less than 10. As stone size number and volume increase, the probability of dissolution within 24 months decreases. Hemolytic disorders, chronic alcoholism, biliary cirrhosis and bacterial invasion of the biliary system predispose to pigment gallstone formation. Pigment stones of primary biliary cirrhosis should be suspected in patients with elevated alkaline phosphates, especially if positive anti-mitochondrial antibodies are present. The presence of microscopic cholesterol crystals in aspirated gallbladder bile, and demonstration of cholesterol super saturation by bile lipid analysis increase the likelihood that the stones are cholesterol stones.
PATIENT SELECTION
Evaluation of Surgical Risk
INDICATIONS AND USAGE
Chenodal (chenodiol tablets) is indicated for patients with radiolucent stones in well-opacifying gallbladders, in whom selective surgery would be undertaken except for the presence of increased surgical risk due to systemic disease or age. The likelihood of successful dissolution is far greater if the stones are floatable or small. For patients with nonfloatable stones, dissolution is less likely and added weight should be given to the risk that more emergent surgery might result form a delay due to unsuccessful treatment. Safety of use beyond 24 months is not established. Chenodiol will not dissolve calcified (radiopaque) or radiolucent bile pigment stones.
CONTRAINDICATIONS
Pregnancy Category X
WARNINGS
PRECAUTIONS
Information for patients
Patients should be counseled on the importance of periodic visits for liver function tests and oral cholecystograms (or ultrasonograms) for monitoring stone dissolution; they should be made aware of the symptoms of gallstone complications and be warned to report immediately such symptoms to the physician. Patients should be instructed on ways to facilitate faithful compliance with the dosage regimen throughout the usual long term of therapy, and on temporary doses reduction if episodes of diarrhea occur.
Drug interactions
Carcinogenesis, mutagenesis, impairment of fertility
A two-year oral study of chenodiol in rats failed to show a carcinogenic potential at the tested levels of 15 to 60 mg/kg/day (1 to 4 times the maximum recommended human dose, MRHD). It has been reported that chenodiol given in long-term studies at oral doses up to 600 mg/kg/day (40 times the MRHD) to rats and 1000 mg/kg/day (65 times the MRHD) to mice induced benign and malignant liver cell tumors in female rats and cholangiomata in female rats and male mice. Two-year studies of lithocholic acid ( a major metabolite of chenodiol) in mice (125 to 250 mg/kg/day) and rats (250 and 500 mg/kg/day) found it not to be carcinogenic. The dietary administration of Lithocholic acid to chickens is reported to cause hepatic adenomatous hyperplasia.
Pregnancy
Pregnancy Category X: See CONTRAINDICATIONS
Nursing mothers
Pediatric use
The safety and effectiveness of chenodiol in children have not been established.
ADVERSE REACTIONS
Hepatobiliary
Dose-related serum aminotransferase (mainly SGPT) elevations, usually not accompanied by rises in alkaline phosphatase or bilirubin, occurred in 30% or more of patients treated with the recommended dose of Chenodiol. In most cases, these elevations were minor (1 ½ to 3 times the upper limit of laboratory normal) and transient, returning to within the normal range within six months despite continued administration of the drug. In 2% to 3% of patients, SGPT levels rose to over three times the upper limit of laboratory normal, recurred on rechallenge with the drug, and required discontinuation of chenodiol treatment. Enzyme levels have returned to normal following withdrawal of chenodiol (see WARNINGS).Morphologic studies of liver biopsies taken before and after 9 and 24 months of treatment with chenodiol have shown that 63% of the patients prior to chenodiol treatment had evidence of intrahepatic cholestasis. Almost all pretreatment patients had electron microscopic abnormalities. By the ninth month of treatment, reexamination of two-thirds of the patients showed an 89% incidence of the signs of intrahepatic cholestasis. Two of 89 patients at the ninth month had lithocholate-like lesions in the canalicular membrane, although there were not clinical enzyme abnormalities in the face of continued treatment and no change in Type 2 light microscopic parameters.
Increased Cholecystectomy Rate
NCGS patients with a history of biliary pain prior to treatment had higher cholecystectomy rates during the study if assigned to low dosage chenodiol (375 mg/day) than if assigned to either placebo or high dosage chenodiol (750 mg/day). The association with low dosage chenodiol though not clearly a causal one, suggests that patients unable to take higher doses of chenodiol may be at greater risk of cholecystectomy.