What is the preferred treatment for dissolution of biliary calculi, UDCA (Ursodeoxycholic acid) or CDCA (Chenodeoxycholic acid)?

UDCA is Superior to CDCA for Dissolution of Biliary Calculi

UDCA (ursodeoxycholic acid) is the preferred bile acid for gallstone dissolution over CDCA (chenodeoxycholic acid) due to superior efficacy, better tolerability, and significantly fewer side effects. 1

Efficacy Comparison

UDCA demonstrates faster dissolution rates in the critical early treatment period:

• UDCA achieved significantly greater stone dissolution than CDCA at 3 and 6 months of treatment in a randomized trial of 223 patients 1
• 74% of total dissolutions with UDCA occurred within the first 6 months, compared to only 42% with CDCA 1
• By 12 months, efficacy became comparable between the two agents, but UDCA's earlier response is clinically advantageous 1

UDCA maintains consistent efficacy across different dosing regimens:

• UDCA was equally effective at both low (7-8 mg/kg/day) and high (14-15 mg/kg/day) doses 1
• UDCA worked effectively on both small and large stones at either dose 1
• CDCA required higher doses (14-15 mg/kg/day) to achieve optimal efficacy and was significantly more effective only on small stones 1

Safety and Tolerability Profile

UDCA has a markedly superior safety profile:

• Diarrhea occurred only in CDCA-treated patients, not with UDCA 1
• Hypertransaminasemia (liver enzyme elevation) occurred only with CDCA 1
• In a multicenter trial, no side effects were observed with UDCA, while CDCA caused diarrhea in 28% of patients 2
• Long-term low-dose therapy with UDCA appears safe with rare side effects 3

Recommended Dosing

The FDA-approved dosing for gallstone dissolution is 8-10 mg/kg/day given in 2-3 divided doses 4:

• This aligns with research showing UDCA effectiveness at 10-15 mg/kg/day 5
• Treatment duration typically requires 1-2 years for complete dissolution 5
• Ultrasound monitoring should occur at 6-month intervals during the first year 4

Clinical Considerations and Limitations

Patient selection is critical for success:

• Best candidates have radiolucent stones smaller than 15 mm diameter with functioning gallbladders 4, 2
• Stones smaller than 5 mm show the highest dissolution rates 3
• If partial dissolution is not evident by 12 months, likelihood of success is greatly reduced 4

Important caveat about recurrence:

• Stone recurrence occurs in up to 50% of patients within 5 years after successful dissolution 4
• This high recurrence rate necessitates careful patient selection and discussion of alternative therapies including cholecystectomy 4

Symptom Improvement

Both agents improve biliary symptoms, with UDCA showing a trend toward better symptomatic relief:

• Dyspeptic and pain symptoms improved in 85% of UDCA-treated patients versus 65% with CDCA 2
• Symptom improvement occurred in 60.9% of patients with biliary-related symptoms prior to treatment 3

Why CDCA Falls Short

CDCA's limitations make it a second-line choice:

• Requires higher doses for optimal efficacy, increasing side effect risk 1
• Dose-dependent diarrhea is common and can be treatment-limiting 1, 2
• Hepatotoxicity risk with transient transaminase elevations 1
• Less predictable efficacy on larger stones 1