<unk>  is an α2 adrenergic agonist. α2 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 α2 agonist activity results in vasoconstriction of blood vessels (as opposed to central α2 agonist activity that decreases sympathetic tone, as can be seen by the medication clonidine). 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 α adrenergic stimulation. This may lead to relaxed ciliary muscle and increased uveoscleral outflow.
Brimonidine
Clonidine
Metergoline
Phenylephrine
Acebutolol
Avacopan
Cabergoline
Drospirenone