Monthly contraceptive: ‘Cool idea’ but far from realization
Success in animal-model test may not be easily replicated in women, endocrine expert suggests.
Initial animal tests support the notion that a uniquely shaped oral contraceptive could someday offer a once-a-month option for birth control, relieving women from the burden of daily pills, scientists said last week.
Preliminary findings of a star-shaped contraceptive were reported in Science Translational Medicine by researchers at Brigham and Women’s Hospital and the Massachusetts Institute of Technology.
In the tests, a single ingested contraceptive delivery system was detected up to 29 days later in the systems of pigs. The contraceptive drug is held within the spokes of the device, which initially are folded vertically inside a capsule. After ingestion, the capsule dissolves and the spokes spring out from a hub into a star shape too big to pass through the opening to the small intestine. The drug remains in the system as digestive acids break down the star over time, slowly releasing a hormone, levonorgestrel, currently used in female birth-control pills.
“It’s a cool idea, but this drug-delivery system has a long way to go to be ready for human use,” said Dr. Stephanie Page, a contraception expert and professor of medicine at the University of Washington School of Medicine.
“In terms of how much drug is released and how much drug is in the bloodstream, the drug levels in the pigs went up and down over time. On top of that, people eat different foods and amounts every day, which can speed or slow their digestion,” affecting the pace of the star’s breakdown, she said. “They’ve shown it can work to release hormones in an animal model over a monthlong period, but they haven’t addressed dosing over the span of several months.”
The researchers involved acknowledged that, although pigs and humans have similar gastric anatomy, pigs’ transit time is slower, and much more work is needed to address other variables such as consistent levels of blood concentrations.
There is strong data that longer-acting methods, like IUDs and implants, are more effective, Page said. “Taking a pill once a month – not having to remember it every day – I think that would be very appealing.”
On the other hand, she added, side effects are a prominent reason that women don’t want to use hormonal contraceptives.
“A different (monthly) regimen with the same side effects doesn’t really speak to that. There might be more room in the market for non-hormonal methods that have yet to be developed. We also think there’s a lot of room for shared responsibility among couples; a once-daily or once-monthly reversible contraception option for men would be a fantastic breakthrough.”
– Brian Donohue, 206.543,7856, bdonohue@uw.edu
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