Drug Distribution Studies in Single Lens Layers Through the Application of A Sectioning Technique

Abstract

The pharmacodynamics of a drug need to be clarified before it can enter the market. The intraocular penetration of drugs which are expected to be used for a long term such as anticataract or anti-glaucoma drugs is a significant problem that we have to fully resolve before commencing their use in clinical trials. The previous studies concerning inrralenticular drug penetration have been performed on entire lens samples, because of technical problems with analysis. In those investigations, the drug concentration obtained was an average value of the whole lens. In cases where small doses of the drug penetrated into only a limited area, the drug concentration in the entire lens might have been shown as below a detected level. In 1987, a new technique that overcame this disadvantage was introduced into the lens research field as a microsectioning analysis of the lens ¹. Utilizing this technology, regional lens layer analysis became possible and much new information was obtained which was not possible from the previous methodology ^1,2. Recently, the author applied this regional lens layer analysis to a drug penetration study in the lens and we found that highly localized low drug concentrations which were not detected in the entire lens samples could be detected with regional lens analysis³. This demonstrates that entire lens analysis is an inadequate method of detecting such low concentrations in the lens. In this study, the author again attempted to investigate inrralenticular drug dynamics utilizing a lens sectioning technique.