Sequential intravenous and twice-daily oral acyclovir for extended prophylaxis of herpes simplex virus infection in marrow transplant patients.

To define an effective and convenient means for providing extended prophylaxis of herpes simplex virus (HSV) infection to chronically immunocompromised patients, we studied a two-part regimen of intravenous, followed by oral, acyclovir after marrow transplantation. Seropositive patients were first given intravenous acyclovir until day 30 after transplant. Intravenous acyclovir (250 mgm/m2) given twice daily to 34 patients during this period was 90% virologically effective among those completing the prophylactic course. A randomized, double-blind comparison of twice-daily oral acyclovir (800 mg) and placebo was then conducted from day 31 to day 75 after transplant in 51 patients. Oral acyclovir significantly delayed the median time to first excretion of HSV when compared with placebo (greater than 100 vs. 70 days after transplant, P = 0.0006) and was completely effective in all patients for the duration of drug administration. Patients receiving extended prophylaxis appeared to have less-severe HSV infection when later recurrences did occur. Sequential intravenous and oral acyclovir given twice daily is an effective and convenient regimen for extended prophylaxis of HSV infection following marrow transplantation, and should be useful in other transplant patients or other chronically immunosuppressed patients as well.