LONG-ACTING THERAPY OF VIRAL RETINITIS WITH S)-1-(3-HYDROXY-2-PHOSPHONYLMETHOXYPROPYL)CYTOSINE

S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine (HPMPC), a high-pot ency antiherpes and anticytomegalovirus (CMV) drug was evaluated in th e treatment of experimental retinitis caused by preretinal herpes simp lex virus (HSV-1) injection in rabbits. HPMPC (100 mu g/0.1 mt) was in travitreally injected 10, 15, 21, 30, or 46 days before, concurrently, or 3, 5, or 7 days after viral inoculation. Ganciclovir (200 mu g/0.1 mL) was intravitreally injected 3, 7, or 10 days before HSV-1 inocula tion, concurrent with viral inoculation, or 3, 5, or 7 days after vira l inoculation. Eyes pretreated with HPMPC were protected from retiniti s for 15-21 days. Ganciclovir did not protect completely even if admin istered 3 days before inoculation. Early treatment of established reti nitis with HPMPC markedly delayed the progression of the infection. Ho wever, with ganciclovir there was delayed progression only in rabbits treated 3 days after viral inoculation. HPMPC had a remarkably potent and prolonged (less than or equal to 1 month) antiviral effect in this retinitis model and may prove more useful than ganciclovir in local t reatment of CMV retinitis.