The once-daily Biktarvy pill, widely used for HIV treatment, can also be a good option for post-exposure prophylaxis (PEP), according to study results presented at the Conference on Retroviruses and Opportunistic Infections (CROI 2024) in Denver.

PEP is a short course of antiretroviral medications taken after sex or another high-risk exposure. Unlike pre-exposure prophylaxis (PrEP), which is taken either on an ongoing basis or before and after sex, PEP involves a full combination regimen taken for about month. To be most effective, it should be started as soon as possible—and no more than 72 hours—after exposure.

The latest Centers for Disease Control and Prevention (CDC) PEP guidelines, last updated in 2016, recommend a 28-day course of tenofovir disoproxil fumarate/emtricitabine (TDF/FTC; Truvada or generic equivalents) plus either raltegravir (Isentress) or dolutegravir (Tivicay). But these regimens require two separate pills, and raltegravir should be taken twice daily.

Biktarvy (bictegravir/tenofovir alafenamide/emtricitabine), an all-in-one pill taken once daily, could be a more convenient alternative. A previous study by Kenneth Mayer, MD, of Fenway Health in Boston, and colleagues, published in 2022, found that Biktarvy was safe, well-tolerated and highly acceptable for PEP, comparing favorably with other regimens. Doctors can prescribe Biktarvy off-label for PEP, but non-specialists who rely on CDC guidance may not be unaware of this option.

The study presented at CROI provides more evidence that Biktarvy can be a good choice for PEP. Darrell Tan, MD, of St. Michael’s Hospital in Toronto, and colleagues evaluated tolerability and adherence to Biktarvy in an ongoing clinical trial of text-messaging support for PEP. At last year’s IDWeek, Tan, Isaac Bogoch, MD, and colleagues reported that PEP-in-pocket—prescribing a course of antiretrovirals for individuals with infrequent but high-risk exposures to have on hand if needed—is a feasible prevention method.

The new study included 120 people who received PEP at emergency departments within the past six days after a confirmed or potential sexual exposure to HIV (one person was found to be HIV positive already and was excluded from the analysis). Most were men who have sex with men, the group was racially diverse and the median age was 29 years. About a quarter had used PEP at least once before.

Participants who initiated PEP with another regimen were switched to Biktarvy for the remainder of the 28 days. Most (89%) had initially been prescribed dolutegravir plus TDF/FTC, two started on raltegravir plus TDF/FTC and 11 started on Biktarvy. They were randomly assigned to either receive check-ins via short SMS text message or standard care with no text messages.

The researchers found that adherence to Biktarvy PEP was high: 88% of the participants with available data reported that they took PEP for at least 28 days. Twelve people stopped PEP early, mostly after 20 days. PEP was generally well tolerated. The most frequently reported adverse events were fatigue, nausea, diarrhea and headache. Six people reported moderate (Grade 2) or worse adverse events, mainly diarrhea.

No HIV seroconversions occurred among the 66 participants who were tested for HIV at 12 weeks. Nearly a quarter went on to start PrEP by their final study visit.

Biktarvy PEP “was safe, well tolerated and associated with high adherence and no HIV seroconversions,” showing that this is an appropriate single-tablet integrase inhibitor-based HIV PEP regimen, the researchers concluded.

In his CROI 2024 review for the New England Journal of Medicine, Paul Sax, MD, of Brigham and Women’s Hospital, noted that given the low incidence of HIV seroconversion in PEP users, “we will never have a comparative clinical trial of different [antiretroviral therapy] strategies that demonstrates one approach is better than another.” Nonetheless, he wrote, Biktarvy “seems like an optimal default choice since it’s simple, well tolerated and has few drug interactions.” He suggested that it might be time to include Biktarvy in PEP guidelines, which are in need of an update.

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