In vitro and in vivo responses of cytomegalovirus to acyclovir.

Laboratory strains and fresh isolates of human cytomegalovirus (HCMV) were tested for sensitivity to acyclovir. Fifty percent inhibition was achieved at about 10 micrograms/ml, but 25 to 100 micrograms/ml was necessary for 90 percent or greater inhibition. Acyclovir was administered intravenously to four patients with congenital cytomegalovirus (CMV) infection. There was only a temporary diminution of virus titer in the urine and no obvious clinical improvement. One child experienced hematuria. Pharmacokinetic studies showed a large volume of distribution and slow excretion of acyclovir with a half-life of approximately three hours.