Large scale human trials of two gels designed to combat the AIDS virus are being planned by British scientists to be carried out in Africa.
Around 40 million worldwide have HIV
Millions of people around the world could soon protect themselves against the HIV virus with the simple dosage.
Experts say around 60 gels, known as microbicides, are now in development with about 14 in clinical trials.
Women could be the main beneficiaries, international development secretary Hilary Benn said on Saturday.
Laboratory trials of the drugs have proved successful, and researchers will tell a conference in London on Sunday that clinical tests will now take place in
five African countries.
A total of 12,000 women are expected to take part in the three-year trials to be held in South Africa, Zambia, Tanzania, Uganda and Cameroon.
If the results are positive, the products could be on the market before the end of the decade.
One expert has estimated that they could save up to two and a half million lives in just three years.
The microbicides were developed through a government-backed study by the Medical Research Council and London's Imperial College and could provide a barrier to the transmission of the HIV virus during sex.
The face of AIDS is a young woman, says International Development Secretary Hilary Benn
Mr Benn said the UK Government had invested £17m in the research.
He told the BBC's Today programme: "This really is potentially very important.
"Women are particularly vulnerable to HIV infection. They are 20% more likely than men to be infected in sub-Saharan Africa.
"The face of HIV is in fact the face of a young woman.
"Women can't always ensure that their partners use condoms.
"What microbicides would do is put the power to protect themselves in the hands of women."
'Obstacles to overcome'
But Mr Benn pointed out that even if the microbicides are shown to work, there would still be a obstacles to
be overcome in making them affordable and getting them to the women who need them most.
The gels or creams are applied internally - before sex - aiming to stop the virus from entering the body.
An estimated 40m people around the world are HIV positive. Many of these may have contracted the virus because they were unable to protect themselves.
For instance, women in developing countries, in particular, are often unable to persuade their partner to wear a condom.
The microbicides work in one of three ways - by killing the virus before it enters the body; by preventing it from taking hold once inside the body; or by creating a barrier to stop it from entering the body in the first place.
The conference on microbicide, which is hosted in London, takes place from 28 to 31 March.