[Changes in ocular hypotensive effect of griseolic acid with isoproterenol, timolol and melanin]

Griseolic acid-ester (GA-ester), one of the strongest cAMP phosphodiesterase inhibitors, was combined with isoproterenol and timolol in this study to evaluate the effect on intraocular pressure (IOP). Furthermore, the ocular hypotensive effect of GA-ester in pigmented and albino rabbits was compared, and the binding ability of GA-ester to synthetic melanin was examined. GA-ester markedly enhanced the hypotensive effect of isoproterenol, and the combination of GA-ester with timolol resulted in an additional fall in IOP. No differences in the hypotensive effect of GA-ester between pigmented and albino rabbits were observed. GA-ester did not bind to synthetic melanin. GA-ester has unique characteristics as an ocular hypotensive agent.