Prophylaxis of herpes infections after bone-marrow transplantation by oral acyclovir.

In a double-blind controlled study, oral acyclovir was compared with placebo in 39 consecutive patients undergoing bone-marrow transplantation. Acyclovir was given at a dose of 200 mg every 6 h from 8 days before to 35 days after bone-marrow transplantation. Pharmacokinetic studies showed good absorption of the drug, despite intestinal damage related to chemoradiotherapy or gut graft-versus-host disease. There was no sign of toxicity. The protection against herpes simplex virus (HSV) infection was complete in the treated group compared with the placebo group even in patients with high anti-HSV antibody titres before transplantation. The same protection was observed against cytomegalovirus (CMV) infection. The frequencies of HSV and CMV infections were the same in both groups after the cessation of treatment.