ATC Group: S01EA Sympathomimetics in glaucoma therapy

Apraclonidine is an α2-adrenergic receptor agonist and a weak α1-adrenergic receptor agonist. It is used for the prevention and treatment of postsurgical intraocular pressure elevation.

Brimonidine is an alpha₂-adrenergic receptor agonist that is 1000-fold more selective for the alpha₂-adrenoceptor than the alpha₁-adrenoreceptor. This selectivity results in no mydriasis and the absence of vasoconstriction in microvessels associated with human retinal xenografts.

Clonidine has been shown to have both central and peripheral sites of action. With long-term treatment clonidine reduces the responsiveness of peripheral vessels to vasoconstrictor and vasodilator substances and to sympathetic nerve stimulation. Early in treatment, however, blood pressure reduction is associated with a central reduction of sympathetic outflow and increased vagal tone.

Epinephrine is a direct acting sympathomimetic agent, which exerts effects on both α and β adrenoceptors. It has more pronounced effects on β than on α adrenoceptors, although α effects prevail at high doses. The effects of adrenaline include increased rate and force of cardiac contraction, cutaneous vasoconstriction and broncho-dilatation.