Brimonidine is a drugacts via decreasing synthesis of aqueous humor, and increasing the amount that drains from the eye through uveoscleral outflow. As a treatment for glaucoma, it is usually given in eyedrop form. Brimonidine is an α2 adrenergic agonist. Alpha 2 agonists, through the activation of a G protein-coupled receptor, inhibit the activity of adenylate cyclase. This reduces cAMP and hence aqueous humour production by the ciliary body. Peripheral alpha 2 agonist activity results in vasoconstriction of blood vessels. This vasoconstriction may explain the acute reduction in aqueous humor flow. The increased uveoscleral outflow from prolonged use may be explained by increased prostaglandin release due to alpha adrenergic stimulation. Brimonidine is indicated for the lowering of intraocular pressure in patients with open-angle glaucoma or ocular hypertension.
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