Overview
DESCRIPTION Ursodiol is a bile acid available as 300 mg capsules suitable for oral administration. Ursodiol USP (ursodeoxycholic acid) is a naturally occurring bile acid found in small quantities in normal human bile and in the biles of certain other mammals. It is a bitter-tasting, white powder freely soluble in ethanol, methanol, and glacial acetic acid; sparingly soluble in chloroform;...
Mechanism of Action
CLINICAL PHARMACOLOGY About 90% of a therapeutic dose of ursodiol is absorbed in the small bowel after oral administration. After absorption, ursodiol enters the portal vein and undergoes efficient extraction from portal blood by the liver (i.e., there is a large “first-pass” effect) where it is conjugated with either glycine or taurine and is then secreted into the hepatic bile ducts. Ursodiol in bile is concentrated in the gallbladder and expelled into the duodenum in gallbladder bile via the cystic and common ducts by gallbladder contractions provoked by physiologic responses to eating. Only small quantities of ursodiol appear in the systemic circulation and very small amounts are excreted into urine. The sites of the drug’s therapeutic actions are in the liver, bile, and gut lumen.
Indications
- INDICATIONS AND USAGE Ursodiol is indicated for patients with radiolucent, noncalcified gallbladder stones
Common Doses
- 10 mg
- 600 mg
- 300 mg
Dosage
DOSAGE AND ADMINISTRATION Gallstone Dissolution The recommended dose for ursodiol treatment of radiolucent gallbladder stones is 8 - 10 mg/kg/day given in 2 or 3 divided doses. Ultrasound images of the gallbladder should be obtained at 6-month intervals for the first year of ursodiol therapy to monitor gallstone response. If gallstones appear to have dissolved, ursodiol therapy should be continued and dissolution confirmed on a repeat ultrasound examination within 1 to 3 months.
Contraindications
- CONTRAINDICATIONS Ursodiol will not dissolve calcified cholesterol stones, radiopaque stones, or radiolucent bile pigment stones. Hence, patients with such stones are not candidates for ursodiol therapy. Patients with compelling reasons for cholecystectomy including unremitting acute cholecystitis, cholangitis, biliary obstruction, gallstone pancreatitis, or biliary-gastrointestinal fistula are not candidates for ursodiol therapy. Allergy to bile acids.
Side Effects
- ADVERSE REACTIONS The nature and frequency of adverse experiences were similar across all groups. The following tables provide comprehensive listings of the adverse experiences reported that occurred with a 5% incidence level: GALLSTONE DISSOLUTION Ursodiol Placebo 8 - 10 mg/kg/day (N = 155) (N = 159) N (%) N (%) Body as a Whole Allergy 8 (5.2) 7 (4.4) Chest Pain 5 (3.2) 10 (6.3) Fatigue 7 (4.5) 8 (5.0) Infection Viral 30 (19.4) 41 (25.8) Digestive System Abdominal Pain 67 (43.2) 70 (44.0) Cholecystitis 8 (5.2) 7 (4.4) Constipation 15 (9.7) 14 (8.8) Diarrhea 42 (27.1) 34 (21.
Interactions
- Drug Interactions Bile acid sequestering agents such as cholestyramine and colestipol may interfere with the action of ursodiol by reducing its absorption. Aluminum-based antacids have been shown to adsorb bile acids in vitro and may be expected to interfere with ursodiol in the same manner as the bile acid sequestering agents. Estrogens, oral contraceptives, and clofibrate (and perhaps other lipid-lowering drugs) increase hepatic cholesterol secretion, and encourage cholesterol gallstone formation and hence may counteract the effectiveness of ursodiol.