Raltegravir plus lamivudine warrants further study as an alternative for PrEP, phase 2 study results presented at the 25th Conference of the British HIV Association suggested.
Thirty-six volunteers, half of whom are women, were randomized to start with seven days of either a lamivudine/raltegravir (Dutrebis) combination or raltegravir (Isentress) only. After a month-long washout, the drug assignment was reversed for another seven days. Each volunteer had two tissue biopsies, but these were staggered to obtain data at different time points.
For the first time in pharmacodynamic research, rectal tissue was taken from women, presenter Julie Fox, M.D., noted. When levels of the two drugs were measured separately from each other, each showed higher concentrations in rectal tissue relative to vaginal tissue. In vaginal tissue, lamivudine levels exceeded raltegravir levels. When the drugs were combined, rectal samples showed 100% protection from HIV after two days, while vaginal biopsies took eight days to reach 100% protection.
That difference is similar to studies of tenofovir/emtricitabine (Truvada), the currently used PrEP drug, noted an aidsmap report. It concluded that lamivudine/raltegravir PrEP could work on an as-needed basis in men, but would need to be taken daily by women.