Radiolucent gallstone dissolution with bedtime UDCA administration

26 patients (20 females and 6 males, mean age 40.5 years +/- SEM 2.20, mean weight 60.2 kg +/- 1.98) with radiolucent gallstones of diameter less than or equal to 10 mm were treated for 6 months with ursodeoxycholic acid (UDCA), a single dose of 600 mg at bedtime. The rate of partial + complete dissolutions was 85%, reaching 100% for gallstones of less than 4 mm diameter. No side effects were observed. In a similar series of patients treated with UDCA t.i.d. at mealtimes (10--12 mg/kg/day) a slightly lower dissolution rate was obtained but the difference was not statistically significant.