Half-life and vitreous clearance of trifluorothymidine after intravitreal injection in the rabbit eye.

To determine the half-life and vitreous clearance of trifluorothymidine, a drug that demonstrates good toxicity against cytomegalovirus (CMV), we injected 200 micrograms of the drug intravitreally in the eyes of nine New Zealand white rabbits. None of the rabbits showed any adverse reactions to the injection or the drug. The rabbits were killed at 3, 6, 12, 24 or 72 hours. High-performance liquid chromatography was used to measure the vitreous trifluorothymidine concentration. The half-life of the drug was found to be 3.15 hours, and the vitreous concentration remained above the ID50 (concentration required to inhibit cytopathic effects by 50% compared with control cultures) for CMV for about 30 hours. We conclude that trifluorothymidine may be of future benefit in the management of CMV retinitis.