OCULAR PHARMACOKINETICS OF ORALLY-ADMINISTERED AZITHROMYCIN IN RABBITS

Azithromycin was orally administered to Dutch-belted rabbits following extracapsular lens extraction in one eye. At various times the animal s were sacrificed, and serum and ocular tissues were obtained for drug level determination by HPLC-EC. Following a single dose, peak levels of drug in ocular tissues were measured within 8 hours (cornea > 0.5 m u g/g [15mg/kg]; > 1.5 mu g/g [30mg/kg]). Highest levels were obtained in iris and ciliary body( > 15 mu g). Measurable tissue levels persis ted for at least 120 hours. Trough levels increased proportionately du ring drug multiple dose administration. Five days following five daily 15mg/kg doses, corneal levels exceeded 0.5 mu g/g, and iris and cilia ry levels were higher than 15 mu g/g. Aqueous humor and serum levels w ere equivalent. Vitreous humor levels, though higher than aqueous humo r, were consistently < 1 mu g/ml. Extracapsular cataract extraction di d not significantly affect drug uptake.