How Microbicides Work

Although not yet on the market, the microbicides currently being tested are similar to spermicides. They would be applied in the vagina as a foam, film, cream, suppository, or gel with the ability to prevent or reduce the risk of infection by STIs. Microbicides would work in one of three ways: killing STI viruses and bacteria, creating a barrier to block infection, or preventing the virus from replicating after the infection has occurred. Ideally, microbicides would be available either with or without spermicide in order to give women the option of becoming pregnant, while still protecting themselves from STIs.

Women Want Microbicides

Microbicide Gel

STIs are one of the most important health concerns for women and one of the least talked about. Currently, an estimated one in five people in the United States has an STI, with more than fifteen million new infections occurring each year. In addition to physical discomfort and social stigma, contracting an STI is also one of the leading causes of infertility, cervical cancer, pelvic inflammatory disease, ectopic pregnancy, and even death. Sadly, many women are unable to protect themselves from STIs because the only effective method approved for protection from STIs is condom use.

This is a problem because heterosexual women are dependent upon their partners to agree to use the condoms, and many women lack the power in their relationships to insist on condom use. Even the female condom, which provides women with an additional option, usually cannot be used with an unwilling partner. Microbicides might be more acceptable than condoms to both men and women, and, if necessary, a woman could even use a microbicide to protect herself without her partner knowing about it. In addition, studies show that, when women control the contraception, rates of consistent and effective use are much higher than if she is dependent on her partner. Researchers expect this would be true for STI prevention as well.[1]

And women want an option they can control. A recent survey estimated that 21.3 million women in the U.S. (35 percent) would be interested in using microbicides.[2]

Barriers to Microbicide Development

The major obstacle to microbicide development is the lack of funding and support from pharmaceutical companies, which do not believe a microbicide will have much potential to make a profit. Based on comparisons to spermicides, which do not make a lot of money for their manufacturers, pharmaceutical companies see little reason for investing a great deal of time or research into microbicide development. But advocates argue that microbicides will prove a more widely popular and profitable venture given the level of demand worldwide.[3] Another concern for potential manufacturers is the liability since microbicides probably will not be 100% effective in protecting against potentially fatal diseases. But this concern is not unique to microbicides, and some pharmaceutical company representatives have acknowledged that if the profit on the product is large enough this concern over liability would likely be dropped.[4]

Some who are skeptical about microbicides are concerned about safety issues and cost for potential users. Microbicides are not, and will likely never be, as effective as condoms in preventing STIs. For one thing, none of the products currently in development offers universal protection; that is, they are specific to one or a few types of STIs. Also, there is concern that use of microbicides could lead to lower use of condoms, which provide better protection. However, preliminary studies in Thailand and surveys in the United States and Europe have shown that this is not the case - women with interest in microbicides are often those who currently use no protection, a definite improvement.[5] Another issue is cost and, while these substances may be more expensive than condoms, surveys in the U.S., Europe, and a number of developing countries have shown that most women are willing to pay for two times the cost of condoms for protection they can control.

From Concept to Product

Currently, a number of different microbicide products have completed the first phase of safety testing and are moving forward in studies with more research subjects for longer periods of time.

Possible products in development include:

• A buffer gel that works by maintaining the natural pH of the vagina, an environment that is too acidic for HIV to survive, countering the alkaline environment that is created by semen
• A gel derived from seaweed which is also used as a thickening agent in ice cream and which coats the vagina, preventing HIV transmission
• A suppository which re-colonizes the vagina with the normal lactobacillus bacteria that produce hydrogen peroxide and help keep the vaginal environment healthy and acidic
• Genetically engineered plants that produce human antibodies against STIs, including HIV[6]

Although some have estimated that a microbicide could be available to the public in the next 5 years, lack of funding and the need for long-term research make a longer time frame seem more realistic.