FRACTAL AND REACTIVE DIMENSIONS OF SOME URSODEOXYCHOLIC ACID SALTS

Six salts of ursodeoxycholic acid, a bile acid largely administered fo r the dissolution of cholesterol gallstones, were obtained as powders by lyophilization of their aqueous solutions. The salts were prepared using lithium, sodium and potassium hydroxide; and using arginine, pyr rolidine ethanol and Tris as organic bases. Thermal, microscopy and ED AX analysis were carried out to identify the nature of the salts. Usin g the parameters of fractal geometry, fractal surface dimension (D-S) and reactive dimension (D-R) to dissolution were also obtained. The ve ry low values (2.02-2.15) for the fractal dimension (D-S) of the parti cle surface suggest that, except in the case of the lithium (2.29) and pyrrolidine ethanol (2.43) salts, the particles thus obtained are cha racterized by smooth and regular surfaces. The D-R for most salts were found to be higher than the corresponding D-S and in a very narrow ra nge of values (2.79-2.84). This fact was briefly discussed and compare d with previous results obtained with other surfactants. The behaviour of the salt with the Tris base was considered separately. (C) 1998 El sevier Science B.V. All rights reserved.