INTRAVITREAL GANCICLOVIR CONCENTRATION AFTER INTRAVENOUS ADMINISTRATION IN AIDS PATIENTS WITH CYTOMEGALOVIRUS RETINITIS - IMPLICATIONS FOR THERAPY

To determine whether therapeutic intravitreal concentrations of gancic lovir are achieved after intravenous administration, vitreous samples were obtained intraoperatively from 23 eyes of 22 AIDS patients with r etinal detachments associated with cytomegalovirus (CMV) retinitis. Th e mean intravitreal ganciclovir concentration of all samples was 0.93 +/- 0.39 mug/mL (3.6 +/- 1.5 muM). This level is near the published tr ough serum concentrations obtained with every-12-h intravenous dosing and well below the peak. It is significantly below the concentration o f ganciclovir required to achieve 50% of viral plaque formation for ma ny human CMV strains. Only a small decrease in vitreous drug levels wa s observed as a function of time after last dose. Intravenous administ ration of ganciclovir results in near-steady-state subtherapeutic intr avitreal ganciclovir concentrations for many CMV isolates. This may ex plain the difficulty of long-term complete suppression of CMV retiniti s.