A drug-releasing intravaginal ring could help prevent women from contracting HIV infection, researchers from Queen's University Belfast will report today at the British Pharmaceutical Conference in Manchester.
The silicone vaginal ring steadily releases aciclovir: a treatment for genital herpes. It is known that women with genital herpes are at increased risk of HIV infection because the genital blisters caused by the infection increase the transmissibility of sexually acquired HIV. "It is widely thought that reducing outbreaks of genital herpes lesions will help to reduce the sexual transmission of HIV," said researcher Dr Karl Malcolm.
The research is part of a long-standing programme, in collaboration with Warner Chilcott Plc, that has a long-term goal to provide alternative strategies for dealing with the escalating HIV epidemic. The present research, partly funded by the International Partnership for Microbicides, involves the development of microbicide-releasing rings for preventing HIV infection and other sexually transmitted infections.
Aciclovir, and related drugs, are currently given as tablets or as an intravaginal cream for treating genital herpes. Dr Malcolm says that recent studies have confirmed that controlled drug delivery from a vaginal ring is potentially more effective and more acceptable to women than gel or cream. "Gel and cream are messy to use and must be applied repeatedly. They also have poor retention in the vagina," he says.
Dr Malcolm says that, in the continued absence of a safe and effective HIV vaccine, and recognising that women in many societies cannot insist on male condom use, the current priority strategy is to develop vaginal microbicides that can prevent or reduce the rate of heterosexual transmission of HIV to women.
"Interestingly, there are many vaginal HIV microbicides currently undergoing clinical evaluation that are very similar in character to the excipients used to enhance aciclovir release in our ring study," Dr Malcolm says. "There is therefore the possibility of combining several anti-HIV compounds within a single ring to obtain a broad spectrum of anti-HIV activity."
In related work, the Belfast team is also investigating the use of intravaginal rings to provide controlled release of antiretroviral drugs for preventing HIV infection.