Antiviral drugs effectively manage herpes infection in children, adults

National report - Children infected with herpes simplex virus can be safely treated with valacyclovir - an antiviral commonly prescribed to treat adult herpes infection, according to research by Richard F. Jacobs, M.D., F.A.A.P., a pediatric infectious disease specialist at Arkansas Children's Hospital.

Herpes in children

Drugs such as acyclovir and valacyclovir have become standard therapy in adults with herpes infection. But acyclovir requires frequent dosing, up to five times a day in some cases. This is especially problematic in children who cannot tolerate pills, Dr. Jacobs says. Valacyclovir, however, is more readily absorbed but is not indicated in children.

"Any time a new medicine is introduced, you want to be able to prescribe it to children too," Dr. Jacobs tells Dermatology Times. "But we never know how much to administer or how often because drugs are rarely tested in children."

Study authors recruited 28 children under the age of 12. All were treated with an oral suspension of valacyclovir, which consisted of a crushed pill mixed with cherry syrup. Patients received 10mg/kg of valacyclovir twice a day for three to five days.

Children tolerated the drug well. There were, however, a few mild adverse events. Ketonuria, uricosuria and neutrophilia was reported in a 4-year-old girl, eosinophilia in a 3-year-old girl, elevated bilirubin in 4-year-old girl and reticulocytosis in a 4-year-old boy.

The side effects were not life threatening, Dr. Jacobs says, but only studies with larger numbers can more accurately indicate adverse effects, he adds.

The study showed that valacyclovir twice a day is pharmacokinectically equivalent to acyclovir five times a day.

"That's a major advance for doctors who take care of these kids," Dr. Jacobs says. "You can treat them in the hospital with acyclovir but what are you going to give them when they go home? Now we have the data to make those decisions."

Treatment in adults

Because of its greater bioavailability, valacyclovir has become the treatment of choice for herpes simplex virus infection over the last few years. Several studies have shown that the drug is not only effective in treating symptomatic outbreaks of both oral and genital herpes, but may also be taken prophylactically to prevent transmission to uninfected partners.

Latest estimates by the Centers for Disease Control and Prevention (CDC) indicate that at least 45 million people (teens and adults) in the United States have herpes, and 1.6 million new cases occur each year.

Promising research

In 2004 Lawrence Corey, M.D., at the University of Washington, Seattle, and Stephen K. Tyring, M.D., Ph.D., at the University of Texas Health Science Center in Houston, Texas, as well as other investigators, published a study in the New England Journal of Medicine that followed almost 1,500 heterosexual couples in which one partner carried genital herpes simplex 2 virus. Only 2.9 percent of uninfected partners who were taking the drug once a day became infected as compared to 10.8 percent taking placebo. Couples were followed for at least eight months.

Dr. Tyring says that since virus-infected cells selectively take up anti-viral drugs such as acyclovir, famciclovir and valacyclovir, side effects from taking the antiviral medications are minimal. Only about 1 percent of patients experienced side effects.

In immunocompromised patients, problems sometimes arise in cases of acyclovir resistant infections. Treating physicians can administer Foscarnet (AstraZeneca LP) intravenously, but the drug can impair kidney function and cause seizures. As an alternative therapy, the CDC recommends compounding cidofovir in a topical 1 percent formulation. The drug has been reported to heal lesions caused by acyclovir-resistant herpes without systemic toxicity.