A Once-a-Month Birth Control Pill Is Coming—Here’s How It Works

In the US, more than 15 million Americans will spend a few seconds every day locating and swallowing a birth control pill. If the tablet—a cordial of contraceptive hormones that trick the body into thinking it’s pregnant—is swallowed during the same three-hour window each day, the method is pretty close to ironclad. But get off-schedule or miss a day, and the pill’s 99 percent pregnancy prevention rate starts to dip. And most people inevitably falter. In the US, nine out of every 100 people using oral birth control become pregnant in any given year.

IUDs and other forms of contraception are more reliable. But so many people still use the pill because it’s cheap, easy, and often available over the counter, rather than requiring a trip to a doctor to have some hormone-emitting device implanted under your skin or inserted into your uterus. For a long time, researchers have been trying to merge the benefits of both—a longer-lasting supply of hormones that are as simple to take as swallowing. But the stomach has proven a worthy nemesis.

A dark, slimy accordion of an organ, it continuously contracts and grinds a corrosive slurry of gastric juices, sending waves of whatever you’ve swallowed crashing over a tiny fissure called the pylorus that leads into the deeper recesses of the gut. If you’re on any sort of oral medication—for high cholesterol or HIV or to maintain your reproductive independence—this angry acid sea is the reason you have to take a pill every single day. Drugs just don’t last long in such a hostile environment.

Unless, that is, you embed them in a flexible silicon ninja star that folds up neatly into pill form.

That’s the solution a team led by scientists at Brigham and Women’s Hospital and MIT came up with about five years ago. Back then they were building slow-release pills designed to deliver treatments for malaria, tuberculosis, and HIV. But in a scientific first, they’ve now demonstrated that the same invention can also deliver a steady drip of contraceptive hormones in the body of a pig for up to 29 days.

“From an engineering aspect, the key novelty is the ability to deliver a drug for a month after a single ingestion event,” says Giovanni Traverso, a gastroenterologist and biomedical engineer at Brigham and Women’s and MIT, who co-authored the new study, published today in Science Translational Medicine. The proof-of-concept experiments were conducted late last year. Since then, the long-lasting contraceptive has begun to be commercially developed by a Boston-area company called Lyndra Therapeutics, which Traverso cofounded with MIT bioengineer Robert Langer in 2015. In July, the startup received $13 million from the Gates Foundation to advance the monthly pill to human trials, with a focus on bringing it to low- and middle-income countries.

To picture how this works, Traverso suggests imagining a six-armed starfish that has folded itself up into a cylinder. Except each arm is made of a body-friendly silicone polymer bonded with levonorgestrel—the hormone used in IUDs like Mirena. The arms are cut with little repeating windows that allow the drug to gradually detach itself from the surrounding polymer matrix. They connect to each other via an elastic core, and when the whole thing is folded up, it fits inside a standard-size capsule. Once swallowed, the capsule dissolves, allowing the arms to spring back into rigid starfish shape.

This is key, because once popped back open, those arms span wider than two centimeters—the diameter of the human pylorus, the gateway to the intestines. Trapped inside the stomach, the silicone starfish slowly seeps the medication through its small pores, allowing the hormone to pass through the gut and into the bloodstream to do its work.