What is the recommended dosage and frequency of ursodiol (ursodeoxycholic acid) for a 95 kg male patient with gallstones?

Ursodiol Dosing for Gallstones in a 95 kg Male

For a 95 kg male patient with gallstones, the recommended dosage of ursodiol is 8-10 mg/kg/day, which equals 760-950 mg daily, divided into 2-3 doses.

Dosing Calculation and Administration

• Based on FDA labeling, the optimal dose for gallstone dissolution is 8-10 mg/kg/day 1
• For a 95 kg patient:
  • At 8 mg/kg: 760 mg daily
  • At 10 mg/kg: 950 mg daily
• Administration should be divided into 2-3 doses throughout the day 1
• Common practical dosing would be:
  • 300 mg three times daily (900 mg total)
  • 400 mg twice daily (800 mg total)

Monitoring and Duration of Therapy

• Ultrasound imaging of the gallbladder should be obtained at 6-month intervals during the first year of therapy to monitor gallstone response 1
• If partial dissolution is observed within the first 6 months, there is >70% chance of eventual complete dissolution with continued treatment 1
• If no partial dissolution is seen by 12 months, the likelihood of success is greatly reduced 1
• Treatment should continue until dissolution is confirmed on repeat ultrasound examination within 1-3 months after stones appear to have dissolved 1

Efficacy Considerations

• Complete stone dissolution can be anticipated in approximately 30% of unselected patients with uncalcified gallstones <20 mm in diameter treated for up to 2 years 1
• Success rates increase to approximately 50% in patients with floating or floatable stones (those with high cholesterol content) 1
• Success rates are inversely related to stone size for stones <20 mm in diameter 1
• Complete dissolution rates reach 81% for stones up to 5 mm in diameter 1

Important Caveats and Limitations

• Patients with calcified gallstones, stones >20 mm in diameter, or those who develop gallbladder non-visualization during treatment rarely achieve dissolution 1
• Stone recurrence after successful dissolution occurs in approximately 30% of patients within 2 years and up to 50% within 5 years 1
• Higher doses of ursodiol (>20 mg/kg/day) should be avoided as they may lead to worse outcomes despite improvement in liver enzymes 2
• Age, sex, weight, degree of obesity, and serum cholesterol level do not affect the chance of stone dissolution 1

Alternative Considerations

• For patients undergoing rapid weight loss (which can increase risk of gallstone formation), a prophylactic dose of 600 mg/day (300 mg twice daily) is recommended 1
• If the patient has symptoms suggesting biliary colic or complications from gallstones, surgical management may be more appropriate than medical dissolution therapy

By following these dosing recommendations and monitoring protocols, you can optimize the chance of successful gallstone dissolution while minimizing the risk of adverse effects.