The successful creation of a device to deliver drugs that can act on both human immunodeficiency virus and herpes has been presented at the 55th Interscience Conference on Antimicrobial Agents and Chemotherapy in San Diego, CA.
The silicone vaginal ring can deliver hydrophilic molecules such as tenofovir, which is active on the most common strain of human immunodeficiency virus (HIV) – HIV-1 – and acyclovir, which is active on the herpes virus. It is hoped the ring will benefit vulnerable women at risk of exposure to HIV and sexually transmitted diseases (STIs).
Its development at the University Jean Monnet of Saint-Etienne, France, was made possible through the collaboration of a team of virologists, chemists and a silicone engineer, who designed the apparatus used to create the ring.
The concept of controlled release technology made from polymeric materials was first established in the 1960s and has been successfully used in vaginal ring devices for delivering long-acting steroids for the treatment of menopausal symptoms and contraception. Drug permeability has been an issue in the design of a successful ring.
The difficulty in creating this ring was that silicone is a hydrophobic compound. The problem was circumvented by adding a hydrophilic compound to the silicone, which allows the drugs to be released from their reservoirs.
Meriam Memmi, author of the study and PhD candidate, explains that some of the rings are able to release concentrations of drugs between 1.5-3.5 mg/day for acyclovir and 3-5 mg/day for tenofovir for up to 50 days.
Such doses are capable of preventing viral STIs such as HIV-1 infection, hepatitis B and genital herpes. The new device demonstrates the ability of silicone rings to continuously deliver hydrophilic antiviral drugs for a long period of time at a concentration that can neutralize the viruses present in semen.
It is now planned to have the rings evaluated in clinical trials, after which it is hoped that they can be produced in large numbers and at low cost.
Cost is important, considering who the rings are designed for. Among women from low-income countries, STIs of viral origin constitute a major public health concern. Many of these women become infected with HIV-1 early in their sexual life, while men tend to contract the disease 7-10 years later in life.
“It is difficult for women in these countries to master the prevention of STIs since the use of condoms is mainly under the control of men,” says Memmi. Vaginal rings can be inserted and removed by the woman herself.
“The aim of our study was to develop a vaginal silicone ring that was nontoxic to the health of users but was capable of delivering multiple active antiviral molecules against various STIs, including HIV, for a long duration.”
Medical News Today have previously reported on the development of a vaginal ring to deliver dapivirine, also to be used against HIV. The technology is soon expected to be on the market.