Shandong Zhanhua Yonghao pharmaceutical & Tech Co.,Ltd

Daily oral administration of tenofovir dipivoxil alone or in combination with emtricitabine as an HIV pre-exposure prophylaxis regimen (PrEP) has been shown to be beneficial for HIV prevention. Although effective treatment of HIV-1 requires multiple antiretroviral drugs, HIV prevention may not require multiple drugs. So researchers from the University of Washington in the US compared the effectiveness of the two prevention programmes. 

Tenofovir dipivoxil alone has been found to be effective in preventing HIV infection. The findings were published in The Lancet in November 2014. 

The researchers designed a randomized, double-blind, placebo-controlled Phase 3 clinical trial. The main population is HIV-1 uninfected individuals from heterosexual couples in Kenya and Uganda. The trial was divided into three groups: placebo, tenofovir dipivoxil, tenofovir dipivoxil and emtricitabine. After the mid-term review, the placebo group of the trial was discontinued and divided into the other two groups in a 1:1 ratio. The primary endpoint events were HIV-1 antibody positive rate and drug safety. 

Of the 4,427 couples in the study, 4,410 (99.6%) received tenofovir diaxil or emtricitabine plus tenofovir diaxil and were followed up for HIV infection. A total of 52 HIV-1 infections occurred during the trial. 31 cases were in the tenofovir dipivoxil group (0.71 cases per 100 person-years) and 21 cases were in the emtricitabine gattenofovir dipivoxil group (0.48 cases per 100 person-years). In the placebo group, the incidence of HIV-1 before trial termination was 2 cases per 100 person-years. 

The efficacy of emtricitabine plus tenofovir dipivoxil in the prevention of HIV-1 was not significantly different from that of tenofovir alone. By comparing plasma tenofovir detection rates between sero-positive and non-positive subjects, the researchers found that taking tenofovir diaxil reduced the risk of HIV infection by 85%, compared with 93% in the emtricitabine plus tenofovir diaxil group. 

There were no significant differences in mortality, incidence of serious adverse events, serum creatinine and phosphorus abnormalities between the two groups. 

These results cannot rule out a slight difference between tenofovir dipivoxil alone and emtricitabine in combination. However, the data from this study suggest that oral tenofovir dipivoxil alone or combined with emtricitabine once a day may be effective in preventing HIV-1 infection in heterosexual couples.