An experimental drug could
eventually offer a new treatment option for genital herpes, a common and
incurable sexually transmitted infection, researchers report.
In a small study,
researchers found that the drug – called pritelivir – substantially curbed
"viral shedding" in people with genital herpes. That means it
decreased the amount of time the virus was active and potentially transmissible
to patients' sexual partners.
The findings, reported in
the issue of the New England Journal of Medicine, are based on 156
patients followed for just four weeks. Experts cautioned that the study is
preliminary and offers a "proof of concept".
First in a new class of drugs
Still, they said, the
results are important because pritelivir is the first in a new class of drugs
that works differently than existing medications for genital herpes. The hope
is that pritelivir will be better at preventing transmission of the virus.
"There was a fairly
dramatic decrease in the probability of viral shedding in this study,"
said Dr. Richard Whitley, an infectious disease expert at the University of
Alabama at Birmingham.
There is still a lot of
research to be done, said Whitley, who wrote an editorial published with the
study. But he said it's good news that drugs that work in new ways are under
"We're at the
beginning of a new era" in genital herpes treatment, Whitley said.
Read: Genital herpes – the basics
Cause of genital herpes
Genital herpes is caused by
the herpes simplex virus – usually the strain known as HSV-2. It's a common
disease: An estimated 16 percent of Americans aged 14 to 49 have an HSV-2
infection, according to the US Centres for Disease Control and Prevention.
The infection may cause
painful sores around the genitals, rectum or mouth. But, more often, it causes
no symptoms or only mild ones, which means most people with HSV are unaware
HSV can be dangerous,
however. If it's passed from a mother to a newborn, the infection can be fatal.
In rare cases, HSV invades the brain and triggers potentially deadly inflammation.
There is no cure for
genital herpes. Once a person is infected, HSV hides out in nerve cells and
reactivates periodically – sometimes causing symptoms, sometimes not.
Currently, three medications can treat symptoms, and – if taken daily –
suppress new symptom outbreaks: acyclovir (brand name Zovirax), famciclovir
(Famvir) and valacyclovir (Valtrex).
Even with that daily
treatment, there is still viral shedding and the drugs cut HSV transmission by
only about half, said Dr. Anna Wald, lead researcher on the new study.
"Clearly, we'd like to
do better," said Wald, a professor of allergy and infectious disease at
the University of Washington, in Seattle.
Oldest existing drug
Acyclovir, the oldest of
the existing drugs, was developed in the 1980s. All three medications had a big
impact on managing genital herpes when they came out, said Dr. Lawrence
Stanberry, an infectious disease expert at Columbia University Medical Centre/New
York-Presbyterian Hospital, in New York City.
Stanberry agreed, however,
that the drugs fall short when it comes to preventing HSV transmission. Plus,
he said, doctors are seeing some viral resistance to acyclovir in patients with
compromised immune systems, such as people with HIV.
The ultimate hope is to
develop drugs that eliminate dormant HSV from the nerve cells, said Stanberry,
who was not involved in the new study.
Genital herpes may never go dormant
Herpes treatment has no effect on HIV