Am J Obstet Gynecol. 1991 Feb;164(2):569-76.
Pharmacokinetics of acyclovir in the term human pregnancy and neonate.
Frenkel LM, Brown ZA, Bryson YJ, Corey L, Unadkat JD, Hensleigh PA, Arvin AM,
Prober CG, Connor JD.
Department of Pediatrics, University of California, Los Angele Center for Health
Sciences 90024-1752.
Concern about neonatal herpes often leads to cesarean delivery of infants in
women with a history of genital herpes. The antiviral drug acyclovir has been
used effectively to suppress genital herpes simplex virus recurrences in
nonpregnant adults. Its administration to pregnant women with recurrent genital
herpes may reduce herpes simplex virus recurrences and thus may decrease the
cesarean section rate among this population. To study the pharmacokinetics,
safety, and patient tolerance of suppressive oral acyclovir, either 200 mg (n =
7) or 400 mg (n = 8) was administered orally every 8 hours to pregnant women
with a history of recurrent herpes simplex virus, from 38 weeks' gestation until
delivery. The mean +/- SD plasma levels for the 200 and 400 mg groups,
respectively, were: first dose peak, 1.7 +/- 0.6 and 2.3 +/- 1.0 mumol/L;
steady-state trough, 0.7 +/- 0.3 and 0.8 +/- 0.6 mumol/L; steady-state peak, 1.9
+/- 1.0 and 3.3 +/- 1.0 mumol/L. In late gestation maternal acyclovir
pharmacokinetics were similar to those of nonpregnant adults from other studies.
Acyclovir was concentrated in the amniotic fluid; however, there was no
accumulation in the fetus (mean maternal/infant plasma ratio at delivery was
1.3). Acyclovir was well tolerated, and no toxicity was seen in the mothers or
infants. The administration of acyclovir, 400 mg every 8 hours, appears
appropriate for use in an efficacy and safety study regarding suppression of
herpes simplex virus recurrences during the last weeks of pregnancy.
