July 16, 2012 — The US Food and Drug Administration (FDA) today
approved tenofovir disoproxil fumarate/emtricitabine (Truvada, Gilead) to
reduce the risk for HIV infection in uninfected individuals at high risk of
catching the virus, possibly through sexual activity, the agency announced.
The antiretroviral agent is now the first drug approved for
prophylactic use. It is currently indicated — in combination with other
antiretrovirals — to treat HIV-infected adults and children aged 12 years and
older.
Patients prescribed tenofovir disoproxil fumarate/emtricitabine
for preexposure prophylaxis (PrEP) are to take the drug daily as part of a
comprehensive HIV prevention strategy, which includes safe sex practices, risk
reduction counseling, and regular HIV testing.
The FDA is adding a boxed warning to the drug to warn that it
should be prescribed for PrEP purposes only for individuals who are confirmed
as HIV-negative both before taking the drug and at least every 3 months
afterward. The antiretroviral is contraindicated for individuals with positive
or unknown HIV status.
The agency predicated its approval of tenofovir disoproxil
fumarate/emtricitabine for PrEP on a risk evaluation and mitigation strategy
(REMS) for proper use of the drug. It consists mostly of a training program for
prescribers to help them counsel patients on several key points:
• The drug
should not become a substitute for a condom, but rather, an adjunct to condom
use and other preventive measures.
• The
antiretroviral must be taken daily, because its effectiveness strongly
correlates to adherence. In addition, intermittent use — as a "party
drug," for example — might spur on the development of Truvada-resistant
HIV.
• Monitoring a
patient's HIV status after the start of PrEP is crucial because if a patient
subsequently becomes infected, he or she should switch from the stand-alone
antiretroviral to the combination of antiretrovirals for treating — as opposed
to preventing — HIV infection. Also, an HIV-positive patient who continues to
take Truvada by itself risks the development of a drug-resistant virus.
In May, the FDA's Antiviral Drugs Advisory Committee strongly
backed the approval of tenofovir disoproxil fumarate/emtricitabine for PrEP,
but recommended a more rigorous REMS than originally proposed by the
manufacturer. Committee members, for example, wanted a requirement that a
patient test negative for HIV before receiving each 30-day supply of the
antiretroviral. The final REMS approved by the agency did not include this
provision.
Debra Birnkrant, MD, director of the Division of Antiviral
Products in the FDA's Center for Drug Evaluation and Research, said in a press
briefing today that the antiretroviral for PreP will help the nation reach a
federal goal of reducing the number of newly diagnosed HIV infections each year
by 25% by 2015. Dr. Birnkrant said that the number of new infections per year
among adults and adolescents has plateaued at 50,000.
No New Adverse Events Identified
Two clinical trials established the safety and effectiveness of
tenofovir disoproxil fumarate/emtricitabine for PrEP. One trial called the
Preexposure Prophylaxis Initiative (iPrEx) found that the antiretroviral
reduced the risk of HIV infection by 42% among men who have sex with men (MSM)
compared with the use of a placebo, according to the FDA. All participants
received monthly HIV testing, free condoms, treatment of other sexually
transmitted infections, and routine counseling.
The other trial, called Partners PreP, compared the use of
tenofovir disoproxil fumarate/emtricitabine, tenofovir disoproxil fumarate by
itself, and a placebo among 4758 couples in Uganda and Kenya who were
serodiscordant. The risk of the HIV-negative partner becoming infected
decreased by 75% if he or she took tenofovir disoproxil fumarate/emtricitabine.
In the 2 studies, "condom use increased over time, and
sexually transmitted infections either remained at baseline, or also
decreased," Dr. Birnkrant said at today's press briefing.
The 2 PrEP clinical trials did not identify any new adverse events
for tenofovir disoproxil fumarate/emtricitabine, according to the FDA. The most
common ones included diarrhea, nausea, abdominal pain, headache, and weight
loss.
The agency also revised the drug's label to warn of the possible
onset or worsening of renal impairment, and decreases in bone density. However,
these adverse events have been uncommon.
More information on today's decision is available on the FDA
Website.
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