A Closer Look at Microbicides

Planned Parenthood spoke with Dr. Zeda Rosenberg, CEO of the International Partnership for Microbicides (IPM), to learn more about microbicide research and the promise it holds. A former scientific director for the HIV Prevention Trials Network at Family Health International, Dr. Rosenberg has been one of the principal people guiding efforts in microbicide research and development, clinical trials, regulatory affairs, global advocacy, and access.

How would you describe microbicides — what they are and how they work — to the average person who is not a doctor or scientist?

Microbicides are vaginal products being developed to prevent the sexual transmission of HIV. Microbicides could take the form of a gel, cream, film, suppository, or sponge, or be contained in a vaginal ring that releases the active ingredient gradually.

What are the implications of microbicides for the global HIV/AIDS epidemic, and what are the social implications for women in developing countries?

Because of its rapid spread and its predilection for the young and most productive members of society, HIV/AIDS ranks among the world's most devastating infectious diseases. The statistics are all too familiar — 14,000 new infections per day, around 40 million cases worldwide, and an increasing incidence among women, especially young women in resource-poor countries.

Nearly two-thirds (64 percent) of all people living with HIV/AIDS are in sub-Saharan Africa. Of these, women account for 59 percent of adults (aged 15-49) living with HIV/AIDS. For young women, the figures are even worse: in sub-Saharan Africa, 75 percent of young people infected with HIV are women and girls.

On a global level, HIV transmission occurs predominantly through heterosexual sex. If men and women had an equal say in their sexual relations, then abstinence, condoms, and mutual monogamy would put an end to the epidemic. But these strategies are not appropriate for everyone because many women do not have control over their sex lives and cannot insist on condom use or mutual fidelity. Microbicides are an HIV-prevention strategy that would be initiated by women, does not interfere with sex, is not necessarily contraceptive, and can be used discreetly.

Can you explain the difference between "first-generation" and "next-generation" microbicide products?

Scientific development of microbicide candidates began in the early 1990s. The first microbicide candidates developed were non-specific compounds that work either by disrupting the viral envelope or binding the virus and preventing it from interacting with its target cells in the vagina. Five of these first-generation microbicides are now in large-scale efficacy trials around the developing world. All of these compounds are formulated in clear gels and are designed to be applied vaginally just prior to sex.

By the late 1990s, development of newer drugs got underway that target specific groups of HIV or the cells they infect. These products, which have become the main focus of developers for the last several years, are based on antiretrovirals (ARVs), drugs that suppress the activity or replication of retroviruses such as HIV and have been used successfully to treat AIDS. These are often referred to as second- or next-generation microbicides and are considered advantageous because they are highly active and could be formulated for sustained-release and, therefore, will not require application just prior to sex, but rather could be used once a day independent of sexual activity or even less frequently.

Right behind these next-generation microbicides are combination products, analogous to the drug "cocktails" that have kept so many infected people alive and healthy for so long. In these products, highly specific ARVs are combined with each other, along with non-specific microbicides similar to those currently in efficacy trials. The goal is to disable the virus before it reaches any vulnerable tissue but, failing complete success, the formulations will also deliver powerful ARVs to the vaginal cells, allowing them to ward off any virus that does invade.

Once a safe and effective microbicide product is available, what challenges do you foresee in terms of access?

IPM is working to address potential challenges to access in several ways, including establishing innovative intellectual property agreements that enable delivery of microbicides in resource-limited settings; selecting for development products that are mindful of the realities of women's lives; and designing policies and delivery strategies to promote successful product distribution. IPM is also assessing regulatory pathways for microbicide licensure in the countries where they will be used.

If microbicide research continues on its current path, how soon would you expect to see a next-generation microbicide product available on the market? What can be done to accelerate this process?

With leadership, sufficient financial resources, collaborative efforts, and product development expertise, women in developing countries could have access to effective microbicides within the next five-to-seven years. It is estimated that global investment of $280 million per year is needed to accelerate microbicide development until satisfactory microbicides are licensed.

Just as with the development of therapeutic drugs to treat AIDS, there will likely be successive "generations" of licensed microbicide products. Development and testing of increasingly effective microbicides and combinations of microbicides will continue after the first microbicide becomes available. Even a partially effective microbicide could prevent millions of new HIV infections and reduce overall HIV incidence in many parts of the world.

© 2006 Planned Parenthood Federation of America, Inc. All rights reserved.