Drug resistant hiv strain, Tribuss and PEP

Question

Dear Doctor How effective is tribuss used as pep against drug resistant hiv strains?

Answer

Hello and thank you for posting.

There isn't any single answer to your question. Tribuss (a generic version of Atripla, containing efavirenz, tenofovir DF and FTC) is generally used as a first-line, initial regimen. It's not generally used to treat drug resistant HIV- and for this reason, would not be a particularly effective PEP treatment in places with resistant virus.

HIV that's drug resistant can be resistant to different medications, so one needs to know the particular resistance pattern of the virus to know if a drug regimen is going to work for a particular virus. Having said that, there are some generalities that can be applied (this is particularly relevant for people living in countries where HIV drug resistance testing is not widely available). In most places, the most common patterns of drug resistance are those to non-nucleoside drugs (like efavirenz) and to the cytosine nukes (FTC and 3TC; cytosine is the "C" in each of these drug abbreviations). Conversely, it's distinctly unusual to see high levels of resistance to protease inhibitors (like darunavir) or integrase inhibitors (like dolutegravir). Indeed, it's recommended in the high income countries that patients living with HIV have drug resistance testing done before initiating treatment, and in low income countries, that community health programs monitor drug resistance patterns and levels to determine how much drug resistance needs to be accounted for in treatment decisions.

Fortunately, PEP is very effective in preventing HIV infectdion when started within 72 hours of exposure. Efavirenz-based PEP is not recommended in the US, largely because of the relatively poor tolerability of efavirenz's psychological side effects and because about 1 in 10 transmitted virus here is already resistant to the drug. For these reasons we use of boosted protease inhibitor- or integrase inhibitor-based PEP regimens. In other countries, these medications might not be available, other medications, like the Tribuss you ask about are used.

I hope that this is helpful, BY