An Australian-developed gel aimed at preventing HIV transmission through vaginal intercourse will be tested on HIV-positive women in Thailand to confirm laboratory trials of its safety and effectiveness in reducing the virus count in the vagina.

It will be the first trial of such a gel on HIV-positive volunteers in Thailand, said Prof Praphan Phanuphak, director of the Thai Red Cross Society's Aids Research Centre.

A number of gels have already passed safety tests in Thailand and some are in the final phase of human testing in other countries, but all of these products were only tested on HIV-negative volunteers, Praphan said.

Called Viva Gel, the product was developed by an Australian bio-company and proved to be safe for use in a small-scale trial involving 24 HIV-negative women in Australia more than a year ago, Praphan said.

The company at first wanted to confirm the results of the trial with further testing on HIV-negative women only, he said. But after discussing the possibility of tests on Thai volunteers with the Thai Red Cross and non-government organisations working on HIV/Aids, it agreed that it was important to test the product on HIV-positive women as well.

"One in three HIV-positive women have an HIV-negative male partner," said Praphan. "Many of these women decide to tell their partners they have HIV, yet fail to convince them to use condoms as the men simply do not believe it's true."

On the other hand, many other HIV-positive women dare not tell their partners and this makes it even harder to convince them to practise safe sex, said the doctor.

The human trial in Australia showed that the gel was safe to use, with no significant side-effects detected, said Praphan.

Prior to that, the gel was proven safe and effective in preventing HIV transmission in rabbits and monkeys, he said. Ninety per cent of the monkeys given the gel before being exposed to the HIV virus through the vagina were protected from infection, compared with a 100-per-cent rate of infection in the control group.

The number of volunteers for the coming trial has not been announced, but the period of trial is said to be between one and two weeks. The volunteers will be given about 10cc of the gel once a day and researchers will check for any harmful side-effects.

They will also test to see whether the gel reduced the amount of HIV virus in the vagina.

Scientists around the world are racing to develop such gels, known as microbicides, as an alternative to female condoms, Praphan said.

Although Thailand seems an unlikely place for the final phase of testing the gel given the low HIV infection rate of the population, he said: "If the final phase is successful, women will have a choice of their own to prevent HIV transmission."

Sureerat Preemanka, deputy director of Aids Access Foundation, said she totally supported the trial but had doubts whether Thailand would benefit.

"Like the HIV vaccine trial, what is missing is that we are not assured of the right to access the product, as a country that participated in its testing, once it is mass produced," she said.

Arthit Khwankhom

The Nation