Taking a once-daily pill helped reduce HIV transmission among MSM, prompting the CDC to issue interim guidance for the drug’s use in the Jan. 28, 2011 Morbidity and Mortality Weekly Report.

Preexposure prohylaxis (PEP) with a combination pill containing two antiretrovirals commonly used to treat HIV (300 mg tenofovir disoproxil fumarate [TDF] and 200 mg emtracitabine [FTC], Truvada, Gilead) provided on average 44% more protection to MSM and transgendered females who have sex with men when used along with other preventive services, results from the iPrEX trail indicated.

First released in November 2010, iPrEX study findings provided the first evidence that TDF plus FTC is safe and partially effective in reducing HIV acquisition in MSM.

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“Given the continued severity of the HIV epidemic, safe and effective new approaches are urgently needed for all populations at risk,” Kevin Fenton, MD, director of the CDC National Center for HIV/AIDS, Viral Hepatitis, STD & TB Prevention, said in statement.

However, efficacy of oral TDF plus FTC varied widely among study participants. Those who used the medication on 90% of days or more, as indicated by self-report, bottles dispensed and pill counts, experienced an approximate 73% reduction in HIV risk, whereas those whose adherence rates were less than 90% experienced an approximate 21% reduction.

“Today’s results are exciting, but it is not time for anyone to stop using condoms or stop following proven prevention methods,” Fenton said.

Currently, the CDC and other U.S. public health organizations are working on official guidelines to ensure that the medication is used properly and in administered in conjunction with HIV preventive services.

“Because the drug is currently approved in the United States for other uses and is commercially available in the United States with a prescription, we are issuing a number of immediate cautions to physicians and gay and bisexual men,” Fenton said.

The following caveats should be observed:

  • As Truvada was the only antiretroviral evaluated for PEP, it is the only medication that should be considered for the purpose. Furthermore, HIV prevention is not a currently labeled indication for this medication.
  • The medication has only been studied in MSM with HIV. No data exists regarding the medications benefits in heterosexuals and injection drug users.
  • PEP should only be initiated in individuals that are confirmed HIV negative and who have been evaluated for other health conditions.
  • PEP with TDF plus FTC does not protect against other STDs, and the CDC encourages continued condom use and testing for HIV and other STDs, as well as counseling to reduce drug use and risky sexual behaviors.
  • Adherence to a daily PEP regimen is critical, as protection was very low among those with low adherence.
  • PEP should be monitored closely with regular HIV testing, risk reduction and adherence counseling and safety monitoring.

“The impact of PEP in the United States will depend on how effectively we utilize it in combination with all available treatment and prevention strategies to reduce the human and economic toll of HIV,” Fenton said.