A double-blind, placebo-controlled cytogenetic study of oral acyclovir in patients with recurrent genital herpes

The antiherpes drug acyclovir breaks chromosomes in vitro at millimolar concentrations and at highly toxic doses in rodents but does not induce single-gene mutations. Recurrent genital herpes patients were examined to determine if such chromosomal damage occurs in peripheral lymphocytes during acute or chronic acyclovir therapy. Patients were randomly assigned to receive acyclovir suppressively and for recurrences, placebo suppressively and acyclovir for recurrences, or placebo suppressively and for recurrences (n greater than or equal to 20 for each group; all treatment double-blind). Normal volunteers and acyclovir-treated cultures served as additional controls. Cytogenetic analyses were done at enrollment (pretreatment), on day 5 of acute acyclovir or placebo treatment for the first postenrollment recurrence (postacute), and at the end of a year on study (postchronic). Cells in metaphase, 150 for each patient, were examined at each time point for structural and numerical chromosomal abnormalities. No cytogenetic effects of chronic or acute oral acyclovir treatment were found relative to lifestyle controls, pretreatment controls, or placebo treatment.