Ursodiol (Ursodiol) - Drug Interactions, Contraindications, Overdosage

DRUG 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.

OVERDOSAGE

Neither accidental nor intentional overdosing with ursodiol has been reported. Doses of ursodiol in the range of 16-20 mg/kg/day have been tolerated for 6-37 months without symptoms by 7 patients. The LD₅₀ for ursodiol in rats is over 5000 mg/kg given over 7-10 days and over 7500 mg/kg for mice. The most likely manifestation of severe overdose with ursodiol would probably be diarrhea, which should be treated symptomatically.

CONTRAINDICATIONS

1. 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.

2. 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.

3. Allergy to bile acids.