Dosage of UDCA for Gallbladder Stone Dissolution
For gallbladder stone dissolution, the recommended dose of ursodeoxycholic acid (UDCA) is 8-10 mg/kg/day, divided into 2 or 3 doses. 1
FDA-Approved Dosing Protocol
The FDA label provides the definitive dosing regimen for gallstone dissolution 1:
- Standard dose: 8-10 mg/kg/day in 2-3 divided doses 1
- Treatment duration requires monitoring with ultrasound at 6-month intervals during the first year 1
- Continue therapy if stones show dissolution, with confirmation ultrasound within 1-3 months after apparent complete dissolution 1
- If partial dissolution is not evident by 12 months, the likelihood of success is greatly reduced and discontinuation should be considered 1
Clinical Efficacy Data
The evidence supporting this dosing comes from multiple clinical trials 1:
- Complete stone dissolution occurs in approximately 30% of unselected patients with uncalcified stones <20 mm treated for up to 2 years 1
- Patients with floating/floatable stones (high cholesterol content) achieve up to 50% dissolution rates 1
- Stone size inversely correlates with success: 81% complete dissolution for stones ≤5 mm diameter 1
- Dose-response studies confirm 8-10 mg/kg/day as optimal, with no additional benefit from higher doses 2, 3, 4
Critical Patient Selection Criteria
Not all patients are suitable candidates for UDCA therapy 1:
- Calcified gallstones rarely dissolve and represent a contraindication 1
- Stones >20 mm in maximal diameter have very low dissolution rates 1
- Gallbladder nonvisualization developing during treatment predicts failure and warrants discontinuation 1
- Pre-treatment nonvisualization on oral cholecystogram is NOT a contraindication 1
Monitoring Requirements
Structured follow-up is essential for treatment success 1:
- Ultrasound imaging every 6 months during the first year 1
- Partial dissolution at 6 months predicts >70% chance of complete dissolution with continued therapy 1, 5
- Partial dissolution at 12 months indicates only 40% probability of complete dissolution 1
- All patients achieving complete dissolution had shown partial dissolution by 6-12 months 5
Important Caveats
Stone recurrence is common after successful dissolution 1:
- Recurrence occurs in 30% of patients within 2 years and up to 50% within 5 years after complete dissolution 1
- Serial ultrasonographic monitoring is required to detect recurrence 1
- Radiolucency must be re-established before initiating another course of UDCA 1
Alternative Dosing Considerations
Lower doses have been studied but show reduced efficacy 4:
- 500 mg daily (approximately 7 mg/kg/day) achieved 29% complete dissolution versus 21% at 1000 mg daily in one study 4
- However, the FDA-approved 8-10 mg/kg/day remains the evidence-based standard 1
The mechanism of action involves desaturating bile cholesterol through increased biliary UDCA concentration (reaching 50-60% of total bile acid pool), which solubilizes cholesterol and prevents precipitation 1, 2, 3