Enhancement of ursodeoxycholic acid bioavailability by cross-linked sodium carboxymethyl cellulose

The bioavailability of ursodeoxycholic acid from a new formulation based on drug-loaded cross-linked sodium carboxymethyl cellulose was studied in man. The plasma levels of ursodeoxycholic acid were determined by gas chromatography-mass spectrometry after derivatization and sample purification by solid-phase extraction. Capsules containing the drug/polymer system were prepared and compared with conventional commercial ursodeoxycholic acid capsules after single oral administration using a randomized crossover experimental design. Although the drug/polymer system improved the in-vitro dissolution rate of ursodeoxycholic acid in simulated intestinal fluid, statistical evaluation of the area under the plasma concentration curves indicated no significant difference in the extent of bioavailability between the two formulations (14.93+/-4.43 vs 14.95+/-5.79 microM h; P > 0.2). However, following the administration of the ursodeoxycholic acid/cross-linked sodium carboxymethyl cellulose system with an enteric-coated capsule, the mean area under the plasma concentration curve (27.60+/-10.11 microM h) was significantly higher than that obtained after treatment with the commercially available ursodeoxycholic acid capsule (16.24+/-8-38 microM h; P < 0.05). We concluded that improved intestinal absorption of the drug was obtained with enteric-coated capsules filled with the ursodeoxycholic acid/polymer system. Moreover, the simplicity of the preparation and the non-toxicity of the polymer used as the carrier represented additional advantages of this dosage form.