What is the role of drug resistance in preexposure prophylaxis (PrEP) for HIV?

Updated: Oct 08, 2019
  • Author: Alejandro Delgado, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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A major concern regarding the use of PrEP is the possibility of acquired drug resistance if HIV infection is transmitted. The genetic barrier to resistance for tenofovir is high but low with emtricitabine. The iPrEx trial that evaluated chemoprophylaxis in men who have sex with men (MSM), did not show any incident tenofovir resistance. However, with a poor adherence level among patients in the intervention arm, the possibility is not eliminated. [2] Emergence of drug resistance could be a potential problem in the future with more widespread use of antiretrovirals for prophylaxis, although such concerns have yet to come to fruition.

HIV transmissions have been reported among a handful of patients taking effective PrEP regimens. These have mostly involved transmission of HIV with multiclass–drug-resistance mutations, [23] reinforcing the need for ongoing condom use in patients who are taking PrEP.

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