By Reuters Staff

(Reuters Health) – In a first, U.S. researchers have developed an experimental, once-a-month contraceptive pill aimed at improving the effectiveness of daily oral contraceptives, which many women forget to take, the team reported on Wednesday.

The pill, which so far has only been tested in pigs, uses a new star-shaped drug delivery system that stays in the digestive tract for days or weeks after being swallowed, researchers from Harvard’s Brigham and Women’s Hospital and the Massachusetts Institute of Technology reported in the journal Science Translational Medicine.

Other types of extended-release contraceptives are already available, in the form of implants under the skin, intrauterine devices, vaginal rings and injectibles. All have the aim of providing women more control over family planning, especially in resource-poor settings.

The experimental pill, funded by the Bill & Melinda Gates Foundation, is the first attempt at a once-a-month oral contraceptive, MIT’s Dr. Robert Langer, one of the study authors, said in a statement.

Daily birth control pills are currently used by about 12% of women in the United States, but many women forget to take a dose, which can reduce the effectiveness. Some studies have estimated that as many as 9% of women taking oral contraception become pregnant each year.

“Coming up with a monthly version of a contraceptive drug could have a tremendous impact on global health,” said study co-author Dr. Giovanni Traverso, who researches ingestible and implantable robotics at MIT and Brigham and Women’s Hospital in Boston.

Previous studies tested the extended-release technology on drugs to treat malaria and HIV. But for the contraceptive pill, the team had to find and test polymers that would not be quickly degraded by stomach acids.

The result is a gelatin-coated, star-shaped capsule with “arms” that unfold and gradually release the contraceptive drug levonorgestrel over a period of several weeks.

Tests in pigs showed the capsule released levonorgestrel over a period of 4 weeks at concentrations that were comparable to those of pigs given immediate-release tablets.

At this point, the drug is still highly experimental, and the researchers caution that it could be 3 to 5 years before it is tested in humans.

The Gates Foundation has awarded a $13 million grant to Lyndra Therapeutics, a company founded by Langer, Traverso and others, to scale up manufacturing and conduct safety studies in advance of human testing.

SOURCE: Science Translational Medicine, online December 4, 2019.