Ursodeoxycholic acid complexation with 2-hydroxypropyl-beta-cyclodextrin increases ursodeoxycholic acid biliary excretion after single oral administration in rats

Complexation of ursodeoxycholic acid (UDCA) with 2-hydroxypropyl-beta-cyclodextrin (HPbCD) (1:1 molar ratio) improves the water solubility and dissolution rate of UDCA and hence its bioavailability. We compared UDCA bile recovery (percentage of administered UDCA dose excreted in bile) after single oral (gavage) administration of UDCA in three different pharmaceutical forms in a bile fistula rat model. Male Sprague-Dawley rats were randomly assigned to 11 groups (6 rats per groups); the bile duct was cannulated after gavage to collect 4-h bile samples. Groups 1, 2 and 3 (fed 5, 10 and 50 mg/kg body weight UDCA/HPbCD complex, respectively) showed (mean values ± SD) 39.2 ± 5.9%, 25.7 ± 4.1% and 9.4 ± 3.1% UDCA bile recovery, respectively; in groups 4, 5 and 6 (fed UDCA suspension formulation containing 5, 10 and 50 mg/kg body weight, respectively) UDCA bile recovery was 33.2 ± 3.6%, 16.9 ± 4.7% and 6.3 ± 0.8%, respectively; groups 7, 8 and 9 (fed UDCA capsule formulation containing 5, 10 and 50 mg/kg body weight, respectively) showed 30.6 ± 9.0%, 21.7 ± 6.4% and 4.7 ± 1.8% UDCA recovery. Groups 10 and 11 (controls) were fed with HPbCD and saline, respectively. Results indicate a significantly (p<0.05) higher bile UDCA recovery in rats fed UDCA-HPbCD complex than in those fed UDCA suspension or UDCA capsule formulations at the same dose. In this model, oral UDCA/HPbCD complex increased UDCA biliary excretion making for greater UDCA enrichment of the bile acid pool than identical doses of common pharmaceutical formulations.