Effects of Topical Clonidine vs. Brimonidine on Choroidal Blood Flow and Intraocular Pressure During Isometric Exercise
Status:
Completed
Trial end date:
2004-12-01
Target enrollment:
Participant gender:
Summary
Brimonidine tartrate is an alpha-2 agonist ocular hypotensive drug that exerts its effect by
causing both a decrease in aqueous production and an increase in uveoscleral outflow. It has
been proven to reduce increased intraocular pressure in glaucoma and ocular hypertension. As
an alpha 2 agonist Brimonidine belongs to the same class of drugs as Clonidine; however, its
molecular structure is sufficiently different to make it more selective for the alpha 2
receptor than Clonidine. Unlike Clonidine, Brimonidine does not appear to have an effect on
the central nervous system and therefore does not cause sedation or systemic hypotension.
In addition to their known effect of lowering intraocular pressure, alpha 2 adrenoceptor
agonists are neuroprotective. It has, however, been shown that Brimonidine is a very potent
vasoconstrictor in the ciliary body thus reducing aqueous humor production. Little is,
however, known about potential vasoconstrictor effects of Brimonidine in the posterior pole
of the eye. This is of clinical importance, because optic nerve head ischemia appears to
contribute to glaucoma pathophysiology.
This study is performed to investigate the effects of topical Clonidine vs. topical
Brimonidine on choroidal blood flow and intraocular pressure during isometric exercise.