In animal models, an experimental, microneedle skin patch provided a therapeutic level of contraceptive hormone for more than 1 month with a single application to the skin, according to study findings published in Nature Biomedical Engineering.
The contraceptive drug levonorgestrel would be delivered using microneedle skin patch technology originally developed for the painless administration of vaccines, according to a press release from the Georgia Institute of Technology. When the patch is applied for several seconds, the microscopic needles break off and remain under the surface of the skin, where biodegradable polymers slowly release the drug.
“There is a lot of interest in providing more options for long-acting contraceptives,” Mark Prausnitz, PhD, a regents professor in the School of Chemical and Biomolecular Engineering at the Georgia Institute of Technology, said in the release. “Our goal is for women to be able to self-administer long-acting contraceptives with the microneedle patch that would be applied to the skin for 5 seconds just once a month.”
Researchers developed a mechanical technique that would allow the drug-containing microneedles to break free from the patch’s backing material, according to the release. To accomplish that, the researchers molded tiny air bubbles into the top of the microneedles, creating a structural weakness. The resulting microneedles are strong enough to be pressed into the skin, but when the patch is then shifted to one side, the force breaks off the tiny structures in the skin. The patch backing can then be discarded.
The microneedles are molded from a blend of a biodegradable polymers commonly used in resorbable sutures.
Testing with rats evaluated only the blood levels of the hormone and did not attempt to determine whether it could prevent pregnancy, according to the researchers.
“The goal was to show that we could enable the concentration of the levonorgestrel to stay above levels that are known to cause contraception in humans,” Prausnitz said in the release.
In developing the experimental contraceptive microneedle patch, the researchers leveraged earlier work on dissolving microneedle patches designed to carry vaccines into the body. A phase 1 clinical trial of influenza vaccination using rapidly dissolving microneedles has been conducted in collaboration with Emory University.
That study suggested that the microneedle patches could be safely used to administer the vaccine.
“We do not yet know how the contraceptive microneedle patches would work in humans,” Prausnitz said. “Because we are using a well-established contraceptive hormone, we are optimistic that the patch will be an effective contraceptive. We also expect that possible skin irritation at the site of patch application will be minimal, but these expectations need to be verified in clinical trials.”
The contraceptive patches tested on the animals contained 100 microneedles. To deliver an adequate dose of levonorgestrel to a human will require a larger patch, which has been fabricated but not yet tested.
The research was supported by Family Health International, funded under a contract with the U.S. Agency for International Development, according to the release.
Disclosures: The authors report no relevant financial disclosures.