Studies Show Value of AIDS Drugs as Prevention

WEDNESDAY, July 11 (HealthDay News) — Researchers have released
the final results of two studies that suggest AIDS drugs can prevent
exposed people in Africa from getting infected with HIV by their sexual
partners. However, another study indicates that it’s a tough job to
convince African women who aren’t at the highest risk to take preventive
medications.

In the big picture, the studies show that “we have a new HIV-prevention
strategy, one that’s quite powerful but also depends on adherence,” said
Dr. Jared Baeten, an associate professor of global health at the
University of Washington, in Seattle. “The next step is figuring out how
to motivate people to take it.”

The studies appeared online July 11 in the New England Journal of
Medicine
.

The general findings of the studies have been previously released, but
only now has the research become available in a medical journal after
going through a peer-review process.

Two studies offer promising details about the potential for the drugs
to prevent — although not all the time — the transmission of HIV to
heterosexual men and women from their infected partners.

One study in Kenya and Uganda looked at heterosexual couples — almost
all married — in which one person was infected with HIV, the virus that
causes AIDS. The uninfected partners were randomly assigned to take an
inactive placebo or a once-daily dose of the drug tenofovir (Viread) or a
tenofovir-emtricitabine combination (Truvada) for up to three years.
Nearly 5,000 people completed the study.

Those who took Truvada had a 75 percent lower risk of becoming infected
with HIV compared to those who received a placebo. The risk was 67 percent
lower in those who took Viread compared to a placebo. Even in those who
got the placebo, the overall risk of getting infected was low: 52 of
1,468, or a little more than 3 percent, did so.

Truvada treatment in the United States costs several thousand dollars a
year, Baeten said, but the discounted price can be as cheap as 25 cents a
day in Africa. The drug, which stops the AIDS virus from reproducing in
people who are infected, appears to do the same thing in uninfected people
who are exposed to the virus, he said. In their cases, the virus doesn’t
already have a foothold in the body so it dies off.

In this study, 10 percent or less of those who took the drugs reported
side effects such as fatigue, diarrhea and nausea, and only in the first
month.

The second study of 1,219 HIV-negative adults in Botswana looked at
Truvada versus a placebo. Comparing the 33 participants who became
infected during the trial — nine people in the drug group and 24 people
on a placebo — the study found those who took Truvada were 62 percent
less likely to become infected with HIV.

In this study, significant loss of bone mineral density was a side
effect for participants receiving the drug, compared to those on a
placebo.

Another study, in Kenya, South Africa and Tanzania, assigned 2,120
women at higher risk of HIV infection to receive Truvada or a placebo.
However, there wasn’t much difference in HIV infection rates between the
two groups — about 5 percent in both became infected.

Baeten explained the finding, saying many women stopped taking the
drug, which prevented an accurate assessment of its effectiveness.

The next step in research into the use of the drugs to prevent
infection is to “figure out how to make them work in the real world,
outside of an intensive research setting,” Baeten said. In the United
States, for example, researchers are studying their use in gay men who are
at high risk for infection.

As for condoms, another major player in HIV prevention, Baeten said the
prevention drugs will add to their level of security or provide some
protection in cases where people can’t use condoms.

In an editorial accompanying the studies, two experts stressed that
medications should never be viewed as a substitute for the condom.

“Although no evidence of increased risky sexual behavior or decreased
condom usage was reported in these studies, we must ensure that
pre-exposure prophylaxis does not indirectly encourage such behavior,”
wrote Dr. Myron Cohen of the University of North Carolina at Chapel Hill
and Dr. Lindsey Baden of Brigham and Women’s Hospital, Boston.

They added that more research is needed to properly assess who stands
to benefit most from these drug regimens, the best timing and dosage, as
well as any potential side effects from long-term use.

More information

For more about AIDS, visit the U.S. National Library of Medicine.

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