Bunazosin (INN) is an α1-adrenergic receptorantagonist.[1] Bunazosin was initially developed to treat benign prostatic hyperplasia (BPH). It has been approved in Japan in a topical form to treat glaucoma. The mechanism of action is a reduction of aqueous outflow through the uveoscleral pathway resulting in lowering the intraocular pressure. It also may act to improve blood flow to the ocular nerve. Systemic Alpha-1 adrenergic receptor antagonists have been implicated in Intraoperative Floppy Iris Syndrome (IFIS). Bunazosin potentially could have the same effect but there has been no research to substantiate this as a risk for cataract surgery.
^Weidinger G (November 1995). "Pharmacokinetic and pharmacodynamic properties and therapeutic use of bunazosin in hypertension. A review". Arzneimittel-Forschung. 45 (11): 1166–71. PMID8929232.