It acts 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 Î±2-adrenergic receptor agonist.
Alpha 2 agonists, through the activation of the Gi GPCR, inhibit the activity of adenylate cyclase. This reduces cAMP and hence aqueous humour production by the ciliary body.