PrEP Provider Toolkit

PrEP Background


The majority of existing PrEP studies have focused on the use of oral F/TDF (Truvada) to prevent sexual transmission of HIV in both assigned sexes (AMAB & AFAB), regardless of sexual orientation. (9)

To date, only one study has specifically investigated the efficacy of tenofovir disoproxil fumarate among people who inject drugs (PWIDs). (10)  Like all medications, it was determined early on that the effectiveness of PrEP varies greatly with adherence.

These initial landmark trials established that with daily adherence…

 F/TDF (Truvada) reduces the risk of acquiring HIV through sex by 99% and through IVDU by 74%.

The DISCOVER trial compared F/TDF (Truvada) directly to F/TAF (Descovy). This study only included MSM/TGWSM. It was concluded that F/TAF (Descovy) is non-inferior to F/TDF (Truvada) in preventing sexual transmission among this select patient population. (11)

The HIV Prevention Trials Network (HPTN) 083 and 084 were then performed in similar fashion and concluded that cabotegravir (Apretude) is superior to F/TDF (Truvada) in MSM/TGWSM and cisgender women, respectively. (12)

It is worth mentioning that the superiority of cabotegravir is primarily derived from improved patient adherence as it does not rely on the need for daily ingestion. Subset analysis does show that effectiveness was similar when F/TDF (Truvada) levels indicated proper adherence. Biochemically, they are essentially equivalent.

There has also been mounting interest and investigation of event-driven PrEP (ED-PrEP), also known as on-demand, non-daily, intermittent, or 2-1-1 PrEP. Rather than daily ingestion, ED-PrEP is a method where PrEP is taken shortly before sex and then the following two days.

ED-PrEP has only been studied using F/TDF (Truvada) to prevent the sexual acquisition of HIV among men who have sex with men (MSM). Existing studies have found that ED-PrEP is non-inferior to daily intake. (13)  This type of use is not currently FDA approved in the U.S. though according to the latest CDC Guidelines, it may be considered in select patients. (14)

  Take Home Points

There are many nuances to what was just discussed, which will be further detailed in the coming sections. For now, the key take-home point is that ALL forms of PrEP are highly effective in preventing HIV infections and should, at the very least, be mentioned to your patients.