CEFPODOXIME-PROXETIL PROTECTION FROM INTESTINAL LUMEN HYDROLYSIS BY OIL-IN-WATER SUBMICRON EMULSIONS

Cefpodoxime proxetil is an orally active, broad spectrum, third genera tion cephalosporin ester, This prodrug was previously found to be hydr olyzed in vitro both in rabbit and human duodenal washing by a choline sterase. The objective of this work was to find a formulation which ca n protect the prodrug: from enzymatic attack. In order to protect the prodrug from enzymatic hydrolysis, the objective was to include it int o the oil phase of an oil-in-water (o/w) emulsion. Somehow, cefpodoxim e proxetil posed specific problems related to the solubilization. The solubilization was obtained with a mixed medium-chain-triglycerides (M CT)/blends of mono-, di-and triglycerides oil phase and the optimal ra tio was defined to be 60:40 (w/w) in order to obtain emulsification. T he emulsifier was a soybean lecithin alone or in mixtures with polysor bate 20. This non-ionic surfactant was chosen since it was found to di rectly inhibit the hydrolysis of cefpodoxime proxetil in vitro using d uodenal washings. The o/w submicron emulsions were proven to be effect ive in protecting the prodrug from enzymatic attack in rabbit duodenal washings compared with a micellar solution and an aqueous solution of cefpodoxime proxetil. An o/w submicron emulsion incorporating polysor bate 20 was found to be the most protective, which can corroborate the inhibitory role of polysorbate itself. (C) 1998 Elsevier Science B.V. All rights reserved.