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.
X-rays of the three pigs that received the experimental treatment revealed that the apparatus stayed mostly intact for the 30 days following ingestion; only two of the 18 arms detached. Loss of arms late in the process isn’t a problem. In fact it’s a feature. That way, the drug starfish naturally breaks down around the 21-day mark, travels through the digestive tract, and gets passed out the other end.
Figuring out the right materials and formulations to ensure the contraption sticks around exactly as long as it should and releases exactly the right amount of medicine is what Lyndra is currently working on. In addition to testing its products in dogs and pigs, the 60-person company has built multiple artificial stomachs it uses to put new designs through the gastric acid-filled ringer. These clear silicon tubes are either squeezed by a robotic arm, like a baker squeezing icing out of a pastry bag, or constricted by strings, similar to the segments of an earthworm. Both techniques mimic the peristaltic waves in the human stomach. They can also be accelerated, allowing Lyndra’s scientists to observe in just a few hours how well the star form will hold up to a week’s worth of real-world peristaltic battering.
These novel testing environments should speed the development of a once-a-month birth control pill. But a commercially available version is still many years away. Lyndra’s CEO, Patricia Hurter, says the company is unlikely to start human testing of its contraceptive contraption until sometime in 2021. It’s planning to spend most of next year conducting surveys in three African countries together with the Gates Foundation to gain a better understanding of regional birth control needs. It’ll also be moving forward with phase I and II trials for longer-lasting malaria, HIV, and schizophrenia treatments.
If the invention succeeds in clinical trials, doctors and public health experts say they expect there to be demand for it. The unknown is whether it will actually make oral birth control more effective.
“With all contraception, improving compliance improves efficacy,” says Erica Pasciullo Cahill, an obstetrician-gynecologist at Stanford University. It’s just not entirely clear that taking a pill once each month will be easier to stick to than doing it once a day, she says. “There’s something to be said for a daily routine.”
Depo-Provera, the hormonal birth control shot given every 12 weeks, is an instructive example. When taken correctly, its failure rate is almost zero. But people take it correctly even less often than the pill, presumably because it’s harder to remember something just once every three months. The NuvaRing, a hormone-secreting vaginal ring that you wear for a month at a time, might offer some insight about the effectiveness of a monthly schedule. Except not enough people use it, so the data (which suggests similar failure rates to the pill) isn’t very reliable.
It’s also unclear if such a monthly pill would also be available over the counter or would require a clinic visit. That could make a huge difference in its popularity, says Megan Christofield, a family planning advisor at Jhpiego, a Johns Hopkins-affiliated global health NGO. (Jhpiego has also received Gates Foundation funding.) “There’s a growing recognition that as we move products from short-acting to longer-acting we oftentimes compromise a person’s control, and a one-month pill offers the opportunity to keep the control in the hands of the person using it,” she says.
It’d be nice to have birth control options that didn’t require a lifetime of chugging hormones, like an “on-demand” pill to prevent ovulation, drugs tailored to your specific genetics, or even (gasp!) a contraceptive for men. For now though, ditching the daily dose may be the convenience most readily within reach.
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