Monthly hormone-free contraceptive device successfully blocks sperm in early-phase study

ByRegina Schaffer

Fact checked byRichard Smith

Key takeaways:

Ovaprene, a monthly hormone-free contraceptive, blocked motile sperm in an early-phase study.
There were no reports of cervicovaginal irritation or adverse effects on normal vaginal bacteria.

An investigational hormone-free contraceptive device left in place for 21 days demonstrated preliminary evidence of contraceptive efficacy in a small early-phase study, researchers reported in Contraception.

The vaginal contraceptive, Ovaprene (Daré Bioscience), is inserted at the end of one menstrual period and left until the beginning of the next, requiring no action at intercourse. The device consists of a silicone ring approximately 2 inches across with a permeable barrier in the middle. Tiny pores in the barrier inhibit movement of sperm while allowing passage of fluids. The ring releases ferrous gluconate, which causes damage to the sperm tail, inhibiting its ability to swim, according to Christine Mauck, MD, MPH, medical director at Daré Bioscience.

“There are many hormonal options, but many women have either experienced side effects from these methods or worry about side effects, and many women don’t like them conceptually,” Mauck told Healio. “Currently available hormone-free methods include permanent sterilization, which many women are not ready for, IUDs, which are not woman-controlled, and ‘on-demand’ methods like condoms, diaphragms and spermicides, that are disruptive to sex. Ovaprene is inserted at the end of one menstrual period and left in until the beginning of the next one, with no hormones and no need to interrupt the sex act. It requires no clinician fitting, and a new product is used each month. Ovaprene works primarily as a physical barrier, but also as a chemical product that interferes with sperm motility.”

In an open-label, postcoital study, researchers assessed how well the device blocked motile sperm from penetrating midcycle cervical mucus for 23 healthy, sexually active women who reported regular menstrual cycles of 24 to 35 days, along with their male partners. Having an average of more than five motile sperm per a high-power field under the microscope is consistent with fertility, according to the researchers; participants had to meet this criterion to proceed in the study.

“To do this, we enrolled women who had chosen to be permanently sterilized in the past and therefore could not get pregnant, since this study was intended to provide some insight into how well Ovaprene might work on blocking sperm, and it would not be appropriate to enroll women at risk of getting pregnant until we had evaluated Ovaprene in a postcoital test study,” Mauck told Healio. “We saw each woman in 21 visits during five menstrual cycles. The first cycle was considered a baseline cycle and involved the woman having vaginal sex with her male partner without using Ovaprene. After sex, we collected mucus from her cervix and checked it for motile sperm.”

For the second cycle, participants used an FDA-approved Caya diaphragm with 3% nonxynol-9 spermicidal gel during sex.

“The purpose of this cycle was to show that our study would get the expected results with an approved product,” Mauck said.

For the third cycle, participants inserted the vaginal contraceptive but did not engage in sex to allow researchers to collect vaginal samples to evaluate the effect of the device on vaginal health. For the fourth and fifth cycles, participant had sex with the device in the vagina. Researchers then assessed whether it successfully reduced the number of sperm in cervical mucus.

All participants had fewer than five progressively motile sperm per high-power field in all 49 cycles with the device, meeting the definition of a successful cycle. Without the device in place, there was an average of 27.2 progressively motile sperm per high-power field. With the device in place, there was an average of 0.5 progressively motile sperm per high-power field. All participants reported they were able to insert, position and remove the device.

In a safety study with 33 participants who completed 77 cycles with the device, there were no reports of cervicovaginal irritation and no adverse effects on normal vaginal bacteria. The most common product-related urogenital treatment-emergent adverse events were bacterial vaginosis and vaginal odor.

“This study and these two papers suggest that Ovaprene is likely to be effective and safe in a larger study enrolling women who can get pregnant and use Ovaprene for a longer time,” Mauck told Healio. “In studies of similar size, diaphragms that demonstrated no motile sperm in the cervical mucus later demonstrated ‘typical use’ contraceptive effectiveness of 86% to 91% in studies evaluating pregnancy rates over 6-month periods.”

Mauck said the study findings were submitted to FDA and based in part on the results, the device is now being evaluated in a single phase 3 pivotal study to establish its effectiveness as a contraceptive.