TOPOGRAPHIC DISTRIBUTION OF PREDNISOLONE IN THE LENS AFTER ORGAN-CULTURE

Topographic distribution of prednisolone in the lens after organ cultu re was investigated. Freshly enucleated pig lenses were divided into t wo groups; the complete vitreous was removed from the lenses in group A, and the adherent parts of the vitreous were left in group B. Groups A and B were each divided into two subgroups which were separated acc ording to drug application: two groups underwent drug application by a divided chamber (Iwata, 1982, DC) and two groups by a closed chamber. The incubation medium was TCM-199 with 2 mu g/ml prednisolone, and th e incubation was performed for 8 h. In order to know the participation of the vitreous in drug penetration into the lens, prednisolone was a pplied by a divided chamber from the anterior or posterior side, with or without vitreous, and incubated for 4 h as a first incubation. A se condary incubation was performed for another 4 h with a medium that di d not contain prednisolone. After the lens incubation, the lenses were separated into single lens layers, and the drug concentration of each lens layer was measured by high performance liquid chromatography. Th e highest prednisolone concentration in the lens was detected by a clo sed chamber in the equatorial part followed by the posterior cortex, a nterior cortex and nucleus. There were no significant differences in d rug concentration due to the direction of drug application or the abse nce or presence of vitreous. The prednisolone distribution pattern in the lens by DC depended on the direction from which the drug was appli ed. The highest drug concentrations were detected in the lens cortex o f the drug-applied. side followed by the equator. No drug was detected in the side of the lens opposite the drug-applied side or in the nucl eus. When a drug was applied from the posterior lens side, the presenc e of the vitreous made a big difference in the amount of drug penetrat ion. The comparison of drug concentration between the absence or prese nce of the vitreous after secondary incubation in a medium that did no t contain prednisolone indicated that the vitreous participates in the drug kinetics of the lens. The experiments suggest that while prednis olone penetration into the posterior lens part is small compared to th at of the anterior part, when the steroid penetrated into the posterio r part it remained there for a long period.