[Affinity of T-3761 to ocular melanin and intraocular dynamics]

The affinity of T-3761 to melanin was examined with synthetic melanin comparing other quinolones. The binding rates with synthetic melanin were from 37% to 48% for tosufloxacin, sparfloxacin, ciprofloxacin and norfloxacin. Binding rate of ofloxacin at 28% was lower and T-3761 was lowest at 22%. Intraocular dynamics of T-3761 and ofloxacin were investigated in pigmented rabbits after a single oral administration at a dose of 20 mg/kg. In both drugs, the concentrations in the melanin bearing tissues were higher and the disappearances from the melanin bearing tissues were more slowly than those of the non-melanin bearing tissues. T-3761 concentrations in the melanin bearing tissues were significantly lower than ofloxacin. In vitro uptake amount to melanin bearing tissue of ofloxacin was 1.4-2.4 times larger than that of T-3761.