A contraceptive gel that protects against bacterial and viral sexually transmitted diseases, including HIV, herpes and gonorrhoea, has passed its first hurdle in its development by North American scientists, writes Steve Farrar.
A team from the United States and Canada told the American Association of Pharmaceutical Scientists' annual meeting this week that phase one safety trials had been a success.
These followed tests in rats, guinea pigs and monkeys that had shown the gel, called Ushercell, gave complete protection against the amounts of virus or bacteria usually encountered during intercourse with an infected individual, and conferred a degree of protection at much higher levels.
The scientists are now preparing to start two years of efficacy trials on humans, in what is developing into a race between several groups of researchers, including US firm Procept, to create a highly effective vaginal contraceptive that blocks STDs.
The gel is based on cellulose sulphate, a spermicidal contraceptive agent that was first tested in the 1960s. The new compound has been shown not only to prevent conception but also to stop the transmission of HIV, the herpes simplex virus and a virus linked to cervical cancer.
It is thought the gel works by interfering with chemical receptors on the pathogen membranes, though its exact mechanism is unknown at present.
The gel could be particularly useful in sub-Saharan Africa, where levels of HIV infection are very high, according to Bill Render, product development co-ordinator with the contraceptive research and development programme based at the Eastern Virginia medical school, which is collaborating with a group led by Larry Zaneveld at the Rush Institute, University of Chicago, and the Canadian firm Polydex Pharmaceuticals.
In the developed world, the scientists believe the gel would find ready markets among young, single women, those who wanted to have a heightened protection against cervical cancer as well as a more general demand.