Effects of topical clonidine on prostaglandin-E-2-induced aqueous flare elevation in pigmented rabbits

We evaluated the role of topical clonidine on experimental ocular inflammat ion. Transcorneal diffusion of prostaglandin (PG) E-2,E- 7.09 x 10(-2) mmol /l, with the use of a glass cylinder was employed to produce aqueous flare elevation in pigmented rabbits. Clonidine was topically administered and yo himbine was injected intravenously. Aqueous flare was measured with a laser flare cell meter. Topical instillation of 0.25% clonidine inhibited 89% of PGE(2)-induced aqueous flare elevation. Instillation of clonidine at 60 or 30 min before and 10 min after PGE(2) inhibited flare significantly. Pretre atment with intravenous yohimbine decreased the clonidine-induced inhibitio n of the flare elevation in a dose-dependent manner. It is possible that th e anti-inflammatory action of topical clonidine may be mediated partly by a lpha(2)-receptors. Copyright (C) 2000 S.Karger AG,Basel.