South Africa is at the crest of a wave of international studies to test the safety and efficacy of a seaweed-based microbicide, which once inserted into a woman’s vagina could help prevent the spread of Aids. The study is particularly important in societies where women have difficulty persuading partners to use condoms.
The final phase three testing of the Carraguard gel is currently underway at Soshanguve in Pretoria, Isipingo in Kwazulu-Natal and Gugulethu in Cape Town.
”Phase one and phase two safety testing were completed successfully, now we have to test a larger group of women, about 6 200 at the three sites,” said Dr Sumen Govender, national clinical study manager for the phase three efficacy trial. Govender, from the non-profit organisation Population Council, said the phase three trial started in March this year and was expected to end in three years’ time.
If proven to be efficacious, plans will be made to mass-produce and market the product.
”Carraguard may have a significant role to play in HIV prevention. Carrageenan [the active ingredient in Carraguard] is found in seaweed and generally regarded as a safe product, and is already found in ice cream and lotions,” said Govender.
He said the Carraguard gel had a negative charge, while the human immunodeficiency virus had a positive charge.
”While all the ways in which the gel offers protection against the transmission of HIV are still being determined, it is believed that Carraguard works by binding to the positively charged regions of the virus and by inhibiting cell-to-cell transmission of the virus, by acting as a barrier between infected and non-infected cells”.
Clinic staff members show trial participants how to properly apply the gel with an applicator and they, in turn, demonstrate to a trained nurse that they know how to insert the gel correctly.
According to Govender, Carraguard would be feasible and cost effective to mass-produce because the seaweed was readily available, a boon for developing and underdeveloped countries buckling under the yoke of the Aids pandemic.
Govender, speaking at the Empilisweni Centre for Wellness Studies in Gugulethu, said the trial was a ”randomised double-blinded placebo trial” in which neither the participants nor the study staff knew who was getting the Carraguard and who the placebo.
Researchers were hoping to see that Carraguard had fewer infections than the placebo.
”We are looking for a 33% difference in seroconversions between the placebo and the Carraguard arms. However, we only expect the entire rate of seroconversion [from HIV negative to HIV positive] across the trial to be about 3,5%.”
Among the major challenges for the trial was to retain all the women participants and the possibility of prevalence rates increasing, which would mean that less women would be eligible and therefore requiring more screening.
According to Dr Lydia Altini, the principal investigator at the Gugulethu site, researchers had enrolled about 800 out of a targeted 2 100 women since March.
”The response has been very good,” she said, adding that the clinic had recruiters helping inform the community about the trial and inviting women to participate.
Some of the criteria needed for women to participate included being over the age of 16, sexually active, HIV negative, living in the area for the past two years and not planning to fall pregnant. Altini said women were screened and benefited during the screening process by having a pap smear and being tested for HIV and other sexually transmitted diseases.
Women were expected to visit the clinic about 10 times for the duration of the trial. They were also provided with a compensation fee for travelling and incidentals.
Vice president of the Population Council’s Centre for Biomedical Research, Dr Elof Johansson, said Carraguard was the first generation of microbicides under development.
”There are second generation products also being developed, which have drugs that actively kill the HIV,” he told Sapa during a visit to Gugulethu. The first generation microbicide does not kill the virus, but only binds the virus.
Johansson said one of the difficulties of the study related to the issue of compliance.
”While we have good information from animal studies that the product is effective, women will have to use it with each act of intercourse for us to know whether it works or not,” he said. Govender said the South African government was aware and supportive of the microbicide trials.
The South African site costs are in the region of R40-million to R60-million and funded by the United States Agency for International Development and the Bill and Mellinda Gates Foundation. — Sapa