Silicone oil as a delivery vehicle for BCNU in rabbit proliferative vitreoretinopathy

The antiproliferative properties of a single intravitreous injection of BCNU [carmustine; 1,3-bis(2 chloroethyl)-1-nitrosourea] dissolved in 1 ml of medical grade, 1,000-centistoke silicone oil were evaluated in a rabbit model of proliferative vitreoretinopathy (PVR). 10 micrograms and 15 micrograms of BCNU in 1 ml silicone oil resulted in a 46% and 27% reduction in the incidence of retinal detachments, respectively. Chi-square tests showed a significant statistical difference (P < 0.05) between the control and treated groups. However, histopathologic examination of the eyes injected with BCNU and silicone oil indicated some retinal disorganization even at the lower therapeutic levels. With a therapeutic index of < 1.0, BCNU in silicone oil has a low margin of safety for treatment of PVR. Nevertheless, this study demonstrates that silicone oil when used for retinal tamponade in PVR may be the vehicle for delivery of a lipophilic antiproliferative agent.