[Ocular hypotensive effects of topically applied bunazosin, an alpha 1-adrenoceptor blocker, in rabbits and cats].

Effects of topically applied bunazosin, an alpha 1-adrenoceptor blocker, on intraocular pressure (IOP) and pupillary diameter were investigated in normotensive rabbits and cats, in addition to experimentally hypertensive rabbits. Bunazosin (0.005% to 0.1%) applied to both eyes significantly lowered IOP in a concentration-dependent manner in normotensive rabbits and cats. The unilateral application of 0.1% bunazosin significantly lowered the IOP in the treated eye, whereas it caused no significant change in the contralateral eye, suggesting that the effect of bunazosin is due mainly to a direct and local action and is not systemic. Bunazosin was also effective in experimentally hypertensive models induced both by water-loading and by alpha-chymotrypsin in rabbits. There was a significant correlation between the IOP decrease caused by bunazosin and the IOP value before the application, indicating that the IOP-lowering action of bunazosin is dependent on the height of the original IOP level. Bunazosin had no influence on pupillary diameter even when 0.5% was applied to rabbits. Topically applied bunazosin may be useful as a new antiglaucoma agent.