Abstract Body

Background: A large Phase 3 trial (Prevent TB TBTC Study 26) indicated that rifapentine (RPT) plus isoniazid (900 mg each once a week) for 3 months was effective and well tolerated for the treatment of latent tuberculosis infection (TB). RPT, an inducer of both CYP3A4 and CYP2B6, is expected to affect the efavirenz (EFV) PK which is a potential concern for Drug-Drug Interaction if RPT is administered in HIV infected subjects under treatment with EFVbased antiretroviral therapy (ART). Interaction towards emtricitabine (FTC) and tenofovir cannot not be ruled out, since these compounds are substrates of transporters and rifamycins, such as RPT may lead to up-regulation of transporters via PXR activation. In this context, a clinical interaction study between RPT and ATRIPLA™ fixed-dose combination of EFV 600 mg, FTC 200 mg, and tenofovir disoproxil fumarate (TDF) 300 mg, was conducted. Methodology: 12 HIV+ TB free subjects with a CD4 > 350 cells/mm3 and viral load