Simulated Absorption of Oral Cephalosporins: Diffusion Through Artificial Lipid Barriers

Abstract

This paper describes the simulated gastro-intestinal absorption of cefradine, cefalexine and cephaloridine through artifical lipid barriers. Cefradine and cefalexine are usually administrated orally and cephaloridine was only used for parenteral injection. These experiments were carried out using a Sartorius absorption simulator and a partition coefficient system. At pH = 3 cefalexine and cefradine have a better diffusion in gastric phase than at pH = 6 in intestinal one. Coefficient partition values which were determined with Sartorius lipid phases confirmed these previous results. Cefalexine and cefradine are amphoteric drugs and are found in 98% under Zwitterion species, the most liposoluble one at pH = 6 and 75% at pH=3. Kp values were determined at pH = 5 and 6 using the surfactant of the gastric phase added to the intestinal phase. These experiments demonstrated the importance of tensioactif agent because the measured Kp are about ten times higher than those determined without any surfactant. Moreover with this absorption simulator, initially used for passive transport, it was possible to verify a facilited transport for cefradine and cefalexine