Abstract

It is now realized that the process of ocular drug and delivery requires a thorough understanding of various anatomical,phyysiological and metabolic features of the eye, in addition to the physico-chemical properties of the drug. Ocular drugs and delivery systems are currently undergoing a process of design optimization due to inherent physiological and anatomical constraints of the eye leading to problems associated with absorption efficiencies of topically applied drugs. Typically, 3 percent or less of the instilled drug in the solution dosage form into the percorneal area is actually absorbed across the cornea 1,3. The poor availability of ocular solution dosage forms therefore led to an intensive search for alternate forms delivery of drugs 4,5: (a) approaches to prolong the contact time of the drug with the corneal surface, and (b) approaches to epithelium or by modifications of chemical structure of the drug molecule. Chemical modifications of the active molecule is often found promising and necessary in order to overcome various problems of ocular drugs pertaining to their: (a)pharmacokinetic insufficiencies, (b) transportability, and (c) site specificity. In the recent years,some significant improvements have been made in this direction. The purpose of this article is to present a brief review of two novel chemical approaches of drug design, soft drugs and site-specific chemical delivery systems. A brief discussion on how these approaches have been utilized to design affective, selective and safe ocular drug delivery systems for the treatment of various pathological conditions and diseases affecting the eye, including treatment of glaucoma, ocular inflammations and infections is presented in this article.