Characterization of Methyl and Ethyl Esters of Amino-Acids as Corneal Permeation Enhancers

Abstract

Introduction: Amino acids are important role-playing components in the maintenance of the normal functions of parts of eye like retina and conjunctiva. In the current study the methyl and ethyl esters of amino acids such as lysine, phenyl alanine and valine were used to enhance the corneal permeation of ketorolac tromethamine. Methods: The amino-acid esters were coupled with the drug ketorolac tromethamine to obtain the test products and were charac- terized by various analytical techniques. The characterized test products were used to formulate the test ophthalmic solutions of Ketorolac tromethamine such as KPD-1, KPD-1A, KPD-2, KPD-2A, KPD-3 and KPD-3A with methyl and ethyl esters of corresponding amino-acids. These test products were subjected percentage corneal hydration and to permeation studies by using Franz diffusion cell mounted with freshly isolated goat cornea. Results: All the test results were compared with those of the standard Ketorolac tromethamine ophthalmic solution and observed that all the test solutions have exhibited less percentage corneal hydration and enhanced corneal permeation of ke- torolac tromethamine. Conclusion: From all the results it can be concluded that the NonsteroidalAnti-Inflammatory Ketorolac has enhanced trans-corneal permeation and reduced corneal hydration when formulated with amino acid transporters by the pro-drug approach in ophthalmic solutions as the formulated pro-drugs have revealed high vitreal drug concentration.