The patch, which contains "micro-needles" absorbed into the skin, is seen as a possible alternative to current long-acting contraceptives. Those methods - intrauterine devices (IUDs) and contraceptive implants - are highly effective at preventing pregnancy. But they have to be inserted by a health care professional, which can be a barrier.
In contrast, the patch would be self-applied - pressed against the skin for about a minute, to release a network of tiny biodegradable "needles" that carry the hormone progestin.
It is only in the early stages of development. Writing in the Nov. 6 issue of Science Advances, the researchers described the results in lab animals and feasibility testing in a small group of women.
"Various forms of long-acting reversible contraception already exist," explained senior researcher Mark Prausnitz, a professor at Georgia Tech's School of Chemical and Biomolecular Engineering, in Atlanta. "Our objective is to have a form that doesn't have to be placed by a health care provider."
One reason, he said, is to improve birth-control access for women in less-developed countries who cannot regularly get to a provider.
But even in countries with more health care resources, like the United States, the patch holds appeal, Prausnitz added.
That point was echoed by Susan Wysocki, a women's health nurse practitioner and medical advisor to the American Sexual Health Association.
Insurance coverage can limit contraception options, she said, and some women do not live near a provider who can insert an IUD or contraceptive implant.
"I'm in favor of having a wide array of contraception options available," said Wysocki, who was not involved in the research. "Different women have different needs. And what works for a woman at one point in her life may not work well at a different point."
The patch contains a special "effervescent" backing, along with a set of micro-needles that carry the birth-control hormone levonorgestrel, a progestin. The patch is pressed against the skin for about a minute, which triggers the effervescent backing to separate from the needles. Those needles are left under the skin, to slowly biodegrade and release levonorgestrel over time.
In tests with lab rats, the researchers found that the micro-needles maintained hormone levels above the threshold needed for human contraception for over a month.
Next, they tested a hormone-free version of the patch in 10 women.
"We wanted to find out, does it hurt?" Prausnitz said. "Do the needles separate from the backing in a short amount of time? Is this approach desirable?"
It turned out that the needles did, indeed, embed in the women's skin quickly. And pain was not an issue: All of the women said the process was either painless or caused "slight" discomfort.
There was some skin redness left behind, but it largely went away within an hour, the researchers said. And nine of the 10 women said they'd prefer a monthly patch application to take the Pill every day.
The big caveat is, the approach has not yet been tested as a contraceptive.
A next step, Prausnitz said, will be to see whether the patch can be formulated to provide longer-term birth control -- perhaps three or six months.
According to Prausnitz, technology does not involve fancy elements. The micro-needles are made of the same biodegradable material used for dissolvable stitches, and the effervescence comes from the same ingredients that make Alka-Seltzer fizzy, he said.
Wysocki said she hopes the research moves forward because a self-administered form of long-acting birth control might appeal to many women.
"To me, control is the key here. A woman could try this, and it would be easy for her to discontinue if she didn't like it," she said.
"I think that if we're serious about preventing unwanted pregnancies," Wysocki said, "it's critical that we make effective birth control more widely available."
Source: Mark Prausnitz, Ph.D., professor, School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta; Susan Wysocki, WHNP-BC, medical advisor, American Sexual Health Association, and president, iWomansHealth; Nov. 6, 2019, Science Advances, online.