Chenodiol (Monograph)

Brand name: Chenodal
Drug class: Cholelitholytic Agents
VA class: GA900
Chemical name: 3α, 7β-dihydroxy-, (3α,5β,7α)-;(2) 3α,7α-Dihydroxy-5β-cholan-24-oic acid
Molecular formula: C₂₄H₄₀O₄
CAS number: 474-25-9

Introduction

Chenodiol, a naturally occurring human bile acid, is used for dissolution of gallstones.

Uses for Chenodiol

Gallstone Dissolution

Dissolution of gallstones in patients with radiolucent stones in well-opacifying gallbladders who are not candidates for surgery because of systemic disease or advanced age. Likelihood of dissolution is far greater if the stones are floatable or small. Chenodiol does not dissolve calcified (radiopaque) or radiolucent bile pigment stones.

Not an appropriate treatment for many patients with gallstones, because of potential hepatoxicity and poor response rate and/or increased need for cholecystectomy in certain groups of patients. Reserve chenodiol for carefully selected patients and monitor liver function.

In patients with nonfloatable stones, chenodiol, particularly at dosages <10 mg/kg daily, produced no reduction in biliary pain and tended to increase the cholecystectomy rate. Consider the risk that patients with nonfloatable stones treated unsuccessfully with chenodiol might require more-emergent surgery because effective treatment is delayed.

Relatively young patients requiring treatment might be better treated by surgery than with chenodiol, because treatment with chenodiol, even if successful, is associated with a high rate of recurrence.

Following complete dissolution, stones have recurred within 5 years in about 50% of patients. Although retreatment with chenodiol has proven successful in dissolving some newly formed stones, the indications for and safety of retreatment are not well defined.

Safety beyond 2 years of use not established. Long-term consequences of repeated courses of chenodiol (e.g., potential for liver toxicity, neoplasia, and elevated cholesterol levels) are not known.

Chenodiol Dosage and Administration

General

• Carefully select patients for chenodiol therapy; consider alternative therapies (e.g., watchful waiting, cholecystectomy, ursodiol).

Administration

Oral Administration

Administer orally twice daily (morning and evening).

Dosage

Adults

Gallstone Disolution

Oral

Recommended dosage range is 13–16 mg/kg daily, given in 2 divided doses. Recommended initial dosage is 250 mg twice daily for the first 2 weeks. Increase dosage by 250 mg daily each week thereafter, until the recommended or maximum tolerated dosage is reached.

If diarrhea occurs during dosage titration or later in treatment, temporarily adjust dosage until symptoms abate, after which the previous dosage usually is tolerated.

Dosages <10 mg/kg daily usually are ineffective and may be associated with increased risk of cholecystectomy; such dosages are not recommended.

Perform serial oral cholecystograms or ultrasonographic examinations to confirm gallstone dissolution (see Monitoring Treatment Response under Cautions); discontinue drug if there is no response by 18 months.

Cautions for Chenodiol

Contraindications

• Women who are or may become pregnant.

• Known hepatocyte dysfunction or bile duct abnormalities (e.g., intrahepatic cholestasis, primary biliary cirrhosis, sclerosing cholangitis).

• Gallbladder confirmed as nonvisualizing after 2 consecutive single doses of dye, radiopaque stone, gallstone complications, or compelling reasons for gallbladder surgery (e.g., unremitting acute cholecystitis, cholangitis, biliary obstruction, gallstone pancreatitis, biliary-GI fistula).

Warnings/Precautions

Warnings

Fetal/Neonatal Morbidity and Mortality

May cause fetal harm; serious hepatic, renal, and adrenal lesions demonstrated in animals.

Contraindicated in women who are or may become pregnant. If used during pregnancy or if patient becomes pregnant, apprise of potential fetal hazard.

Hepatic Effects

Significant hepatotoxicity (a major abnormality identified by light microscopy of liver biopsy specimen or major elevation in serum aminotransferase concentrations) occurred in 3% of patients receiving chenodiol 750 mg daily versus 0.4% of patients receiving chenodiol 375 mg daily or placebo in a large study (National Cooperative Gallstone Study).

Serum aminotransferase (mainly ALT) concentrations increased to >3 times the ULN, recurred on rechallenge with the drug, and required drug discontinuance in 2–3% of patients receiving chenodiol. Concentrations returned to normal following drug withdrawal.

Reserve chenodiol for carefully selected patients without preexisting liver disease (see Gallstone Dissolution under Uses); carefully monitor serum aminotransferase concentrations to detect drug-induced liver toxicity.

Risk of Colon Cancer

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 known carcinogens.

The possibility that chenodiol therapy might contribute to colon cancer in otherwise susceptible individuals cannot be ruled out.

General Precautions

Monitoring for Hepatotoxicity

Optimal frequency of monitoring liver function tests during chenodiol therapy is not known.

Manufacturer recommends monitoring serum aminotransferase levels monthly for the first 3 months and every 3 months thereafter.

Discontinue chenodiol if minor, usually transient elevations (1.5–3 times the ULN) persist longer than 3–6 months. Resume drug treatment only after the aminotransferase level returns to normal; however, allowing the elevations to persist over such an interval is not known to be safe.

Discontinue chenodiol immediately if elevations >3 times the ULN occur; such elevations usually reoccur on challenge.

Cholesterol Monitoring

Monitor serum cholesterol concentrations at 6-month intervals. May be advisable to discontinue the drug if cholesterol concentrations increase above the acceptable age-adjusted limit for the patient.

Monitoring Treatment Response

To monitor stone dissolution, perform oral cholecystograms or ultrasonograms at 6- to 9-month intervals. Confirm complete dissolution by a repeat test after 1–3 months of continued chenodiol administration.

Most patients who eventually achieve complete dissolution will show partial or complete dissolution at the first such on-treatment test. If partial dissolution is not seen by 9–12 months, the likelihood of success with continued therapy is greatly reduced. Discontinue chenodiol if there is no response by 18 months.

Stone recurrence can be expected within 5 years in 50% of patients. After confirmed dissolution, discontinue treatment.

Perform serial cholecystograms or ultrasonograms to monitor for recurrence, keeping in mind that radiolucency and gallbladder function should be established before starting another course of chenodiol.

GI Effects

Dose-related diarrhea reported in 30–40% of patients; occurs most commonly when treatment is initiated, but may occur at any time during treatment. Usually mild, translucent, and well tolerated. Steady epigastric pain with nausea typical of lithiasis (biliary colic) usually is easily distinguishable from the crampy abdominal pain of drug-induced diarrhea.

Usually does not interfere with therapy, but dosage reduction may be required. Antidiarrheal therapy is useful in some patients. Drug discontinuance required in approximately 3% of patients.

Specific Populations

Pregnancy

Category X. (See Fetal/Neonatal Morbidity and Mortality and also see Contraindications under Cautions.)

Lactation

Not known whether chenodiol is distributed into human milk. Use with caution.

Pediatric Use

Safety and efficacy in pediatric patients not established.

Common Adverse Effects

Diarrhea (usually mild, translucent, well tolerated), increased serum total cholesterol and LDL-cholesterol, decreased WBC (not <3000/mm³).

Drug Interactions

Specific Drugs

Chenodiol Pharmacokinetics

Absorption

Bioavailability

Following oral administration, well absorbed from the small intestine. Undergoes enterohepatic circulation.

Distribution

Extent

After the drug is conjugated in the liver, it is distributed into bile.

Chenodiol crosses the placenta in humans.

Not known whether chenodiol is distributed into human milk.

Elimination

Metabolism

Chenodiol is conjugated with glycine and taurine in the liver.

Elimination Route

Chenodiol is converted by bacterial action in the colon to lithocholic acid. About 80% of litholate is excreted in the feces; the remainder is absorbed and converted in the liver to poorly absorbed sulfolithocholyl conjugates. During chenodiol therapy there is only a minor increase in biliary lithocholate, while fecal bile acids are increased threefold to fourfold.

Stability

Storage

Oral

Tablets

Tightly closed containers at 20–25°C.

Actions

• 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 gallbladder visualized by oral cholecystography.

• Has no effect on radiopaque (calcified) gallstones or radiolucent bile pigment stones.

Advice to Patients

• Importance of periodic visits for liver function tests and oral cholecystograms or ultrasonograms for monitoring stone dissolution.

• Importance of being aware of the symptoms of gallstone complications and of immediately reporting such symptoms to the clinician.

• Importance of long-term compliance with the dosage regimen; need for temporary dosage reduction if episodes of diarrhea occur.

• Importance of women informing clinicians immediately if they are or plan to become pregnant or plan to breast-feed; necessity of advising women to avoid pregnancy during therapy. Necessity of advising pregnant women of the risk to the fetus.

• Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs, as well as any concomitant illnesses.

• Importance of informing patients of other important precautionary information. (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

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