LIPOSOME-ENCAPSULATED (S)-1-(3-HYDROXY-2-PHOSPHONYLMETHOXYPROPYL) FORLONG-ACTING THERAPY OF VIRAL RETINITIS

The effect of liposome-encapsulated S)-1-(3-hydroxy-2-phosphonylmethox ypropyl)cytosine (HPMPC; cidofovir) was evaluated as prophylaxis in a rabbit model of experimentally induced retinitis caused by preretinal inoculation of herpes simplex virus type 1 (HSV-1). Cidofovir (100 mu g) in liposomes (0.1 mL) was injected intravitreally 10-120 days befor e retinal inoculation with HSV-1, Twenty-two of 26 eyes pretreated wit h liposome-encapsulated cidofovir 10-60 days before HSV-1 inoculation were protected from experimentally induced retinitis, and 2 of 5 eyes pretreated 120 days before inoculation were protected, Intravitreal le vels of cidofovir were low (0.7 mu g/mL) but detectable 120 days after injection, One 100-mu g intravitreal injection of liposome-encapsulat ed cidofovir appears to have a remarkably potent and prolonged (up to 4 months) antiviral effect in this experimental model of HSV-1 retinit is, Since HPMPC is even more potent against cytomegalovirus than HSV-1 , liposome-encapsulated cidofovir may prove to be effective local ther apy for AIDS patients with cytomegalovirus retinitis.