Overview
Ursodeoxycholic acid (ursodiol) is a bile acid used to dissolve cholesterol gallstones in patients with functioning gallbladders and to treat primary biliary cholangitis. It works by reducing cholesterol secretion into bile and protecting liver cells from toxic bile acids.
Mechanism of Action
Ursodeoxycholic acid is a hydrophilic bile acid that replaces toxic hydrophobic bile acids in the bile acid pool. It reduces cholesterol saturation in bile by inhibiting intestinal cholesterol absorption and decreasing hepatic cholesterol secretion. Additionally, it protects hepatocytes from apoptosis induced by toxic bile acids and has immunomodulatory effects.
Indications
- Dissolution of radiolucent, non-calcified gallbladder stones in patients with functioning gallbladders who are not candidates for surgery
- Treatment of primary biliary cholangitis (PBC)
Common Doses
- 250 mg capsules
- 300 mg capsules
- 500 mg tablets
- Powder for 250 mg/5 mL suspension
Dosage
For gallstone dissolution: 8-10 mg/kg/day in 2-3 divided doses. For PBC: 13-15 mg/kg/day in 2-4 divided doses. Treatment duration varies from months to years based on indication and response.
Contraindications
- Hypersensitivity to ursodeoxycholic acid or bile acids
- Patients with calcified cholesterol stones, radiopaque stones, or bile pigment stones
- Patients with non-functioning gallbladders
- Patients with acute cholecystitis, cholangitis, biliary obstruction, or frequent biliary colic
Side Effects
- Diarrhea (most common)
- Nausea
- Abdominal pain
- Constipation
- Headache
- Dizziness
- Back pain
- Elevated liver enzymes
- Rash
- Pruritus
Interactions
- Bile acid sequestrants (cholestyramine, colestipol) reduce absorption - administer at least 2 hours apart
- Aluminum-based antacids may reduce absorption
- Cyclosporine levels may be reduced
- Oral contraceptives and estrogen may counteract gallstone dissolution effects
Counseling Points
- Take with food to improve absorption and reduce gastrointestinal side effects
- Report severe diarrhea, abdominal pain, or yellowing of skin/eyes immediately
- Continue treatment as prescribed even if symptoms improve
- Regular ultrasound monitoring required for gallstone patients
- Do not stop medication without consulting healthcare provider