A comparison of the opacifying effects of carteolol.HCl and 8-hydroxycarteolol.HCl in the isolated porcine cornea.

Using an in vitro method the authors have investigated whether 8-hydroxycarteolol.HCl(8-OH carteolol) and 8-OH carteolol with benzalkonium chloride affected intact isolated porcine corneas to the same or to a different degree as carteolol.HCl (carteolol) or carteolol with benzalkonium chloride. These ophthalmically used drugs were applied as solutions of varying concentrations to the epithelial surface only, to the endothelial surface only, or to both surfaces of porcine corneas. The resultant opacities were determined using an opacitometer. In general, 8-OH carteolol and 8-OH carteolol with benzalkonium chloride caused less opacity to develop than carteolol and carteolol with benzalkonium chloride. This suggests that 8-OH carteolol may be a safer drug than carteolol for ophthalmic use. It is very interesting to note that compounds with two nitrogens, e.g., 8-OH carteolol, caused greater opacity in the intact cornea when applied to the endothelial surface than when applied to both the epithelial and endothelial surfaces; however, compounds with none or one nitrogen caused greater opacity in the intact cornea when applied to both surfaces than when applied to the endothelial surface.