Abstract
Purpose::
To investigate the vitreous penetration of acyclovir, the active metabolite of valacyclovir, after oral administration of valacyclovir.
Methods::
Prospective case series of patients who were scheduled for elective pars plana vitrectomy and were given four oral doses (three times daily) of valacyclovir 1000 mg preoperatively. Plasma and undiluted vitreous samples were obtained intraoperatively and subsequently analyzed with high performance liquid chromatography to determine the concentrations of acyclovir present.
Results::
Preliminary data on three subjects are reported. The patients ranged in age from 68 to 77 years and all had normal renal and hepatic function. The mean plasma acyclovir concentration was 4.40 ± 0.35 mcg/mL (range 3.98 to 4.80 mcg/mL). The mean vitreous concentration was 1.10 ± 0.25 mcg/mL (range 0.84 to 1.33 mcg/mL). The mean vitreous to plasma concentration ratio was 0.25 ± 0.04 (range 0.21 to 0.28).
Conclusions::
Orally administered valacyclovir results in vitreous penetration by acyclovir. The acyclovir vitreous concentrations achieved in non-inflamed eyes are in the therapeutic ranges of acyclovir for the treatment of herpes simplex 1, herpes simplex 2, and varicella zoster virus infections. This suggests that orally administered valacyclovir may be an alternative treatment option to intravenous acyclovir in the treatment of viral retinal infections such as acute retinal necrosis.
Keywords: retinitis • herpes simplex virus • drug toxicity/drug effects