Alpha-adrenergic agonist

Overview
An adrenergic alpha-agonist is a drug which selectively stimulates alpha adrenergic receptors. The alpha-adrenergic receptor has two subclasses α1 and α2. Although complete selectivity between receptor agonism is rarely achieved, phenylephrine is an α1 agonist, while clonidine and methyldopa are α2 partial agonists.

An example is xylazine.

Alpha-adrenergic agonists are used in the treatment of glaucoma by decreasing the production of aqueous fluid by the ciliary bodies of the eye.