Treatment with the antiviral drug valacyclovir, sold as Valtrex, curbs recurrent bouts of genital herpes in pregnant women, a study shows. Moreover, no safety concerns were identified in mothers, fetuses, or neonates exposed to the drug.

Genital herpes is usually caused by herpes simplex virus type-2 (HSV-2). It’s estimated that up to 25 percent of pregnant women have been exposed to the virus and about 20 percent of them have a recurrence during pregnancy. This often occurs late in pregnancy, raising the risk that mom will transmit the virus to her baby, which is a big concern given that HSV-2 can be deadly to the fetus or newborn infant.

To curb the odds that mom will pass the virus on to her infant, it’s recommended that women with active genital herpes sores, or early symptoms suggestive of an outbreak, deliver by cesarean section.

It’s previously been reported that the antiviral drug acyclovir, started late in pregnancy can reduce recurrent genital herpes bouts and may reduce the need for cesarean delivery resulting from active HSV-2 lesions.

In their study, Dr. William W. Andrews and colleagues at the University of Alabama at Birmingham assessed the value of Valtrex, a cousin of acyclovir, in 112 pregnant HSV-2-positive women. At 36 weeks’ gestation, they were randomized to oral Valtrex (500 milligrams) or placebo twice daily until delivery.

During that period, the proportion of women who had clinical HSV recurrence in the active treatment group (10.5 percent) was significantly lower than that in the placebo group (27.4 percent).

HSV shedding within 7 days of delivery was similar in both groups (10.4 percent versus 12.0 percent). This was also true of clinical HSV sores at the time of delivery (5.3 percent versus 14.6 percent). At up to 2 weeks after delivery, no neonates were seen to have symptomatic HSV-2 infection. As mentioned, Valtrex treatment appeared safe for both mother and baby.

“The results of this trial with valacyclovir,” Andrews told Reuters Health, “are similar to previous reports which have utilized acyclovir.” Doctors who choose late gestation HSV viral suppression, he added, “might take advantage of the more favorable bioavailability and reduced daily dosage times for valacyclovir compared with acyclovir.”

SOURCE: American Journal of Obstetrics and Gynecology March 2006.