This study will evaluate how safe and tolerable a combination of taking three-drugs will be for the purpose of preventing HIV transmission after a high-risk sexual contact exposure in HIV uninfected adults.

This study will evaluate a three drug regimen in the form of two pills which will be taken for 28 days for the prevention of HIV infection. Two drugs are combined in an FDA-approved pill called TRUVADA, containing the HIV medications, tenofovir disoproxil fumarate 300mg and emtricitabine 200mg, taken as one pill once a day. The third drug is a new formulation, raltegravir 400mg pill taken twice a day.

Inclusion Criteria:

• HIV uninfected on the basis of a negative HIV Rapid Test, EIA or Western blot, and a negative HIV-1 RNA assay
• Possible non-occupational exposure to HIV-1, recent enough to permit receiving the first dose of study medication within 72 hours from the end of the exposure.
• Able to understand the study procedures and willing to sign informed consent

Exclusion Criteria:

• Any active psychiatric illness or active drug or alcohol abuse that, in the opinion of the investigator, could prevent compliance with study procedures.
• Pregnancy.
• Chronic hepatitis B infection, diagnosed by either positive serum HBsAg or positive serum HBV DNA; or prior lamivudine therapy for hepatitis B.
• Creatinine clearance less than 50 mL/min as calculated by Cockcroft-Gault formula.
• Unwillingness to participate in study procedures, including Mental Health referral and intervention.
• Known intolerance or allergy to tenofovir DF, emtricitabine or raltegravir.
• Use of prohibited concomitant medication: dilantin, phenobarbital and rifampin which cannot be used with raltegravir.

28 days

Limitations of the current study included:

1. Reliance on self-reports to measure adherence
2. Study population almost exclusively male (reflecting the demographics of people who call Fenway Health's hotline after an acute sexual exposure)