Effect of bunazosin hydrochloride on intraocular pressure and aqueous humor dynamics in normotensive human eyes
T. Oshika, M. Araie, T. Sugiyama, M. Nakajima and I. Azuma
Department of Ophthalmology, University of Tokyo, School of Medicine, Japan.
We investigated the effects of topical administration of bunazosin
hydrochloride, a new selective alpha 1-adrenergic antagonist, on
intraocular pressure and aqueous humor dynamics in normal human eyes. In
the single-dose study, all concentrations of bunazosin (0.025%, 0.05%,
0.1%, and 0.2%) significantly lowered intraocular pressure in a
concentration-dependent manner. Administration of multiple doses of 0.1%
bunazosin revealed no occurrence of tachyphylaxis after 1 week. Single
application of 0.1% bunazosin had no significant influence on aqueous flow
rate, tonographic outflow facility, or episcleral venous pressure,
suggesting that bunazosin reduces intraocular pressure by increasing
uveoscleral outflow. Aqueous protein concentration was found to be
unaltered by bunazosin, indicating that blood-aqueous barrier permeability
to protein molecules remained unchanged. We conclude that bunazosin may be
a possible new antiglaucoma agent with a mechanism of action different from
those currently in use for treating ocular hypertension.
