<prompt> Answer this question truthfullyWhat is the purpose of administering Tenofovir TDF and Emtricitabine FTC as a combination drug, and in what context is it typically used?  <response>: <reason> Tenofovir TDF and Emtricitabine FTC are typically given as a combination drug for pre-exposure prophylaxis of HIV, which is a preventive measure taken to reduce the risk of HIV infection in individuals who are at high risk of contracting the virus. 