Clinical trials are to begin soon on a new vaginal ring that promises to
provide months of protection
against pregnancy, HIV
and herpes, US researchers said.
The device, which is similar to birth control rings already on the market,
delivers both an antiretroviral drug and a contraceptive which are slowly
released over 90 days.
Sascha Edelstein on latest advancements in birth control
A report on the ring and how it was developed by scientists at North-western
University is published in the peer-reviewed journal PLOS ONE.
A valuable tool
The ring could offer women an alternative that eliminates the anxiety of
missed pills and requires a lower dose of an antiretroviral
drug aimed at preventing HIV since it is delivered at the point of
Scientists and Aids prevention advocates have been trying to develop a ring
like this for a long time, said Rowena Johnston, vice president and director of
research at amfAR, the Foundation for Aids Research.
"If you have something that is long acting that people don't have to
think about every time they have sex but something that is in place, that is
thought to be a boon," she told AFP.
While the ring is only designed to protect against transmission during
vaginal sex, it could be a valuable tool for some women, she said.
gel cuts HIV risk
"And it is probably not easily detected by the male partner, if that is
important to you," Johnston added.
Both drugs released by the ring – levonorgestrel
and tenofovir – are already used to prevent pregnancy and the spread of HIV.
Tenofovir – which inhibits HIV and herpes replication in susceptible cells – is taken
orally by 3.5 million HIV-infected people worldwide.
It has been found to help prevent HIV infection as well, but so far only
with pills that must be taken daily.
Products only work when used
A gel which delivers tenofovir has been found to be somewhat effective in
clinical trials but the gel needs to be inserted into the vagina before and
Many of the women in the clinical trials did not use the gel every time they
"Products only work when they are used," said study co-author
David Friend, product development director at CONRAD, which develops
reproductive health technologies for low-income countries and is affiliated
with Eastern Virginia Medical School.
"By having a ring that can remain in the body for up to 90 days, our
hope is that this ring will offer a solution to increase adherence, and
therefore provide greater protection against HIV while also preventing
pregnancy," Friend said.
A lot of engineering
The differences between the two drugs presented a "huge" design
challenge, said North-western University biomedical engineer Patrick Kiser, who
holds the ring's patent.
Tenofovir dissolves easily whereas the contraceptive drug levonorgestrel is
highly insoluble. The drugs also had to be delivered in drastically different – but consistent – doses.
"A lot of engineering has gone into developing the ring," Kiser
The ring uses a new kind of polymer – or chain of molecules – that swells
in the presence of bodily fluids and is capable of delivering up to 100 times
more tenofovir than current intravaginal rings.
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