Contraceptive Ring Protects Against HIV



A team from Northwestern University has spent five years developing a new contraceptive ring. The ring not only protects against unwanted pregnancies but also delivers the antiretroviral medication tenofovir to protect against HIV. As an added benefit, tenofovir, the antiretroviral drug being used, has also been shown to reduce genital herpes transmission. While the device may protect against genital herpes, the two main goals of the contraceptive ring are to protect against HIV and unwanted pregnancy.

Patrick Kiser is the biomedical engineer at McCormick School of Engineering and Applied Science and professor at Northwestern University’s department of obstetrics and gynecology who devised the ring. He and his team had to overcome some basic engineering issues in order for the ring to work properly. The drugs released from the ring, tenofovir to combat exposure to HIV and levonorgestrel to protect against pregnancy, are two very different drugs. To begin with, tenofovir is water soluble while levonorgestrel is not. Additionally, the diffusion rates of the two drugs are vastly different with the contraceptive dose at 10 micrograms daily and tenofovir, the antiviral, at a much higher 10 milligrams a day. The dosage amounts vary by a degree of  a thousand times for each drug.

Kiser and his team of researchers ended up creating two distinct reservoirs using two different polyurethane polymers. They then separated the two with another polymer. The reservoirs are adhered to each other, together yet divided. The intravaginal ring (IVF) is 5.5 centimeters in diameter and may be worn for up to 90 days. Currently being manufactured, the device should soon be tested in women.     HIV

A contraceptive ring of this nature, one that protects against HIV, unwanted pregnancies, and possibly even genital herpes, is the first of its kind. In the last 40 years, there has not been much innovation for contraceptive rings. The developmental details were released through publication in PLOS ONE on March 5. PLOS ONE is an open access, peer reviewed online journal.

Kiser built on his previous research for the development of an IVR for just the prevention of HIV transmission. The drug chosen, tenofovir, is already approved by the FDA and is currently taken orally by patients who are already HIV positive. The levonorgestrel, the drug in the ring used for birth control, is also found in the Mirena IUD. The FDA application papers for the ring are being finalized and once done, the clinical trials will begin.

The World Health Organization reports that there are 35 million people living with HIV in today’s world. Additionally, there are 222 million women who are currently not using any type of contraception who would like to protect against pregnancy. This IVR combats both and may be left in place for up to three months. At that time, the ring may then be briefly removed, cleaned, and reinserted for another period of up to three months.

While oral tonofovir has been shown to be effective against HIV transmission between partners, research indicated that the gel form of the drug was less effective. The research team found that the drop in effectiveness was mostly due to patient neglect as opposed to a difference of delivery method. The studies showed that if the gel were used correctly or if it can be delivered at the levels that will be released from the ring, the vaginal transmission of HIV will be completely protected against. In fact, the dosage of the drug can be lowered and maintain effectiveness because it is being delivered at the exact viral transmission site. This may mean that women who currently experience side effects from the oral form may be able to alleviate those symptoms by using the ring.

Once the FDA process of approval has been finalized, the ring will begin a small clinical trial. The next step after the clinical trial will be safety and efficacy trials. The device still has years to go before coming to market but Kiser is optimistic. If all goes well, once released, the public will be able to purchase a contraceptive ring that not only protects against pregnancy but also against HIV transmission and possibly genital herpes, as well.

By Dee Mueller

Northwestern University
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