Release Studies from Lyotropic Liquid Crystal Systems

Autor: Ibrahim, Hussein G.
Zdroj: Journal of Pharmaceutical Sciences; August 1989, Vol. 78 Issue: 8 p683-687, 5p
Abstrakt: A temperature-composition diagram of systems containing the nonionic surfactant polyoxethylene (20) isonexadecyl ether (1) and water was established. Three different anisotropic areas existed over the concentration range 33–80% of 1. Release of salicylic acid from liquid crystalline phases of 1 into aqueous buffer across lipoidal barriers was also studied. Rates of transfer as a function of percent loading from a neat mesophase containing 37% of 1 and also from systems with different molecular packing were determined. Apparent activation energies of transfer from an ordered solvent containing 37% of 1 and from an isotropic medium of the same chemical composition were found to be 33.3 and 9.4 kcal/mol, respectively. These findings suggest a pronounced effect of medium structure on the interfacial resistance of the barrier.
Databáze: Supplemental Index
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