Keeping herpes infections contained

Houston - Dermatologists need to urge patients with herpes infections to take a nucleoside analog drug daily to prevent the transmission of genital herpes, according to Stephen Tyring, M.D., Ph.D., M.B.A., professor of dermatology, University of Texas Health Sciences Center, Houston.

"We are obligated to advise our patients," he says. "If the FDA has approved that indication for the drug, we are potentially legally responsible if we do not inform them they can reduce transmission of genital herpes by taking the drug."

Indications Valacyclovir is indicated for the prevention of genital herpes outbreaks and for treatment of herpes zoster (shingles). Approved by the U.S. Food and Drug Administration in 1995, valacyclovir is taken orally three times a day for seven days to treat shingles. It is taken twice a day for three days to treat genital herpes. It decreases the pain and itching associated with genital herpes infections and helps sores to heal. Valacyclovir is taken once daily to prevent the outbreaks of genital herpes and to reduce transmission of the virus.

Research study Dr. Tyring co-authored a study published in 2004 in the New England Journal of Medicine that looked at using valacyclovir to reduce the risk of transmission of genital herpes. The prospective study concluded daily suppressive therapy decreased the likelihood of transmission of HSV-2 among discordant partners.

The study looked at nearly 1,500 immunocompetent, heterosexual mon-ogamous couples. One partner had clinically symptomatic genital HSV-2 and one was susceptible to HSV-2.

Subjects with HSV-2 were assigned to receive either 500 mg of valacyclovir once daily or placebo for eight months. The susceptible partner was evaluated monthly for clinical signs and symptoms of genital herpes. Source partners were followed for recurrences of genital herpes.

Investigators found HSV-2 developed in four of 743 susceptible partners who were administered valacyclovir, compared with 16 of 741 who were given placebo, a finding that was statistically significant. Specifically, contracting HSV-2 occurred in 14 of the susceptible partners who received valacyclovir, or 1.9 percent, compared with 27, or 3.6 percent, who received placebo.

Furthermore, DNA samples of genital secretions detected HSV on 2.9 percent of the days among partners who were infected with HSV-2 but who received valacyclovir. By contrast HSV was detected in genital secretions on 10.8 percent of the days among those receiving placebo, another statistically significant difference between controls and the treatment group.

Mean rates of recurrence were 0.11 per month among treated subjects with HSV and 0.40 per month among non-treated subjects with HSV.

"The more common form of transmission is from man to woman," Dr. Tyring adds. "This is why the condition is more prevalent in women."

Valacyclovir can be administered to treat herpes simplex I if outbreaks are frequent, he says.

Side effects Side effects of the medication are rare but include headache, upset stomach, vomiting, diarrhea and constipation. If patients have kidney disease, the dosage of valacyclovir may need to be reduced.