Intravaginal ring could be used in AIDS prevention

An intravaginal ring that releases antibiotic has been developed by scientists at Queen's University Belfast.

The ring will be used initially to treat bacterial vaginosis but it also has potential use as part of a strategy to prevent HIV infection.

The Belfast researchers have a longstanding research programme into the development of intravaginal rings as drug delivery systems. The rings are made of silicone rubber and are positioned high in the vagina. They can be formulated to release drug over weeks or months, for either local or systemic delivery.

In the case of bacterial vaginosis, metronidazole diffuses through the silicone and dissolves in the vaginal fluid. It is released from the ring over 14 days in decreasing amounts over the treatment period, explained researcher Karl Malcolm: 'The release profile mimics the reduction in bacterial population and avoids unnecessary exposure to drug.'

The Belfast researchers believe that the ability to deliver controlled amounts of drug vaginally could provide significant advantages for many patients. For example, a ring releasing metronidazole, either alone or in conjunction with an antiretroviral agent, could have considerable potential in preventing HIV infection. Wheareas HIV does not survive long in the normal acidic environment of the vagina, it thrives at the elevated pH associated with bacterial vaginosis infection,' Malcolm said. 'Simply treating existing, and in many cases asymptomatic, vaginal infections could have a massive impact on sexually transmitted HIV statistics.'