Gilda Tachedjian Burnet Institute, Melbourne, VIC Last reviewed: August 2019 Background Microbicides are chemical entities that can be formulated in gels, films, tablets, capsules or intravaginal rings (IVR) for application to the vagina or rectum to prevent the transmission of HIV and other sexually transmissible infections (1, 2). While male condoms are known to protect …
Microbicides for the prevention of HIV infection Read More »
Despite major advances in HIV treatment and prevention, HIV infection remains a significant global health threat including in women. In 2017, around 7000 adolescent girls and young women became infected with HIV every week (9). Most of this burden is in sub-Saharan Africa where around 3 out of 4 new HIV infections occur in 15-19 …
Burden of HIV infection in women globally and in Australia Read More »
IVRs comprising a silicone matrix that releases the ARV drug dapivirine, over one month is the only microbicide evaluated in a phase III clinical trial demonstrating efficacy (27 and 31%) in preventing HIV transmission in women as determined in The Ring Study and ASPIRE studies (11, 12). The dapivirine ring is currently being evaluated in …
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The microbicide field has been overtaken by oral PrEP comprising of ARVs (i.e. tenofovir and emtricitabine [Truvada]) normally used for HIV treatment (see Biomedical Prevention Section). Several clinical trials (iPrEX, Partners PrEP, TDF2, PROUD) have demonstrated the efficacy of oral daily PrEP in MSM and high-risk heterosexual men and women including serodiscordant couples (13-15). The …
While the TDF2 (15) and Partners PrEP (14) studies indicate that oral PrEP can work in women, other trials in high-risk women (FEM-PrEP and VOICE) showed no efficacy (20, 21). This lack of efficacy was largely attributed to poor adherence (22). However, other factors such HIV subtype exposure, mode of transmission, and the percent of …
There are exciting advances in the development of long-acting injectable and implants to deliver sustained levels of ARV drugs (25, 26). However, like oral PrEP these modalities deliver the drug systemically, which may discourage their use. Major advantages of these delivery strategies are that dosing is discrete and independent of coitus, which should maximise adherence …
Multipurpose prevention technologies (MPTs) are designed to target HIV prevention as well as an additional indication such as preventing unintended pregnancies or transmission of other sexually transmissible infections (STIs) such as herpes simplex virus (HSV) infection. Delivery strategies under development include sustained release IVRs (27). While a ring with additional indications, such as preventing pregnancy, …
Nonspecific microbicides Surfactants and detergents Microbicides were originally intended to have broad-spectrum activity against all STIs and contain non-drug compounds for over the counter use without a prescription (2). The first generation microbicides were non-specific agents comprising surfactants and detergents that directly inactivate viral and bacterial STIs (28). The nonionic surfactant, nonoxynol-9 (an over the …
1% Tenofovir gel was shown to achieve an overall efficacy of 39% in the CAPRISA 004 study compared to women receiving placebo gel and 54% efficacy in women who had >80% adherence to gel use (65). Since only 54% efficacy in preventing HIV acquisition was achieved in highly adherent women, this suggests that other factors, …
Biological factors that attenuate topical microbicide efficacy Read More »
Shattock RJ, Moore JP. Inhibiting sexual transmission of HIV-1 infection. Nat Rev Microbiol. 2003;1(1):25-34. Shattock RJ, Rosenberg Z. Microbicides: topical prevention against HIV. Cold Spring Harb Perspect Med. 2012;2(2):a007385. Weller S, Davis K. Condom effectiveness in reducing heterosexual HIV transmission. Cochrane Database Syst Rev. 2002(1):CD003255. McGowan I. The development of rectal microbicides for HIV prevention. …
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