Other long-acting contraceptives, such as intrauterine devices (IUDs), require the work of trained health professionals and needle-injected drugs.
And “non-hormonal contraceptive methods, such as condoms and diaphragms, provide physical barriers for pregnancy protection, but these barrier methods, even when accompanied by spermicide, usually have high failure rates due in part to poor patient acceptance and compliance with correct use,” according to the study.
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“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 contraceptive drug levonorgestrel over time,” according to researchers. LNG has a long history of clinical contraceptive use.
Animal testing on rats showed the patches, which contain 100 tiny microneedles created in collaboration with Emory University researchers, kept LNG levels at concentrations known to cause contraception in humans. The experiments didn’t try to determine whether it could prevent pregnancy in rats.
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Researchers don’t know how the patches will work in humans, but “because we are using a well-established contraceptive hormone, we are optimistic that the patch will be an effective contraceptive,” study author and Georgia Tech professor Mark Prausnitz said.
Humans will require larger patches with more than 100 microneedles to ensure an adequate dose of levonorgestrel is delivered. A larger patch has not yet been tested, but researchers hope to develop one that, when applied for five seconds once a month, could contain enough hormone to provide contraception for as long as six months.
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Prausnitz expects “that possible skin irritation at the site of patch application will be minimal, but these expectations need to be verified in clinical trials.” Prausnitz is also a shareholder in and paid advisor to companies developing microneedle-based products, a “potential conflict of interest” managed by both Georgia Tech and Emory University.
The study highlighted potential limitations, such as a relatively small sample of animals and the need for technical advances to create a larger patch with a higher LNG dose for humans.
Currently, approximately 46 percent of the 6 million pregnancies in the United States are unplanned, and many women get pregnant while using birth control like the pill and condoms, both of which have high rates of failure compared to costlier options like the IUD. Access to an OB/GYN is another obstacle.
"Beyond the obvious stress of an unplanned major life event, women facing an unplanned pregnancy are less likely to complete college and also face decreased economic opportunities, which can in turn affect the health and economic opportunities of their children," the Washington Post reported last May. "The costs to society, in health-care dollars, economic supports and lost wages, are significant."
Researchers hope this new affordable, longer-acting contraceptive patch with self-administer abilities “can provide women with greater access and autonomy” to better control their fertility.
Read the full study at nature.com.