Pregnancy and child

Once a month contraceptive pill in development

"Once-a-month oral contraceptive pill in tests," reports BBC News.

Researchers in the US are developing a pill that can stay in the stomach for a month, slowly releasing hormones to prevent pregnancy.

The team have developed a capsule designed to be swallowed. Once in the stomach, the capsule dissolves and a 6-sided star structure unravels and gradually releases the synthetic hormone levonorgestrel.

The star has been designed to be wider than the opening between the stomach and the small intestine, so that it stays in the stomach.

So far the pill has been tested in 3 pigs. It stayed in place in the pigs' stomachs for 29 days and levonorgestrel was present in blood tests throughout this time.

Further research is needed to see if the hormone dose released from the pill will be high enough to prevent pregnancy, but not so high that it causes side effects. There will also need to be extensive tests to establish if this type of delivery system is safe to use in humans.

If you want to use a long-acting contraceptive, various methods are already available. The options include:

Where did the story come from?

The study was carried out by researchers from the Massachusetts Institute of Technology, Northeastern University in Boston, Harvard Medical School in Boston and the University of Southern California.

It was funded by the Bill and Melinda Gates foundation. The study was published in the peer-reviewed medical journal Science Translational Medicine and is free to read online.

The UK media mostly reported the study accurately and colourfully, with Mail Online creatively terming the new technology "medical origami".

The Daily Mirror's headline, "Scientists develop contraceptive pill that women only have to take once a month", is misleading, as it is over-optimistic. If the new pill works as well in women as it does in pigs, then this may prove to be true. However, there is currently no evidence that this is the case.

What kind of research was this?

This was a laboratory study in which various drug designs were tested in simulated gastric fluid and then in pigs. This is a very early stage in the drug development cycle. There will need to be further refinement before any human tests can be performed to look at safety and effectiveness.

What did the research involve?

The researchers designed a drug delivery system that could remain in the stomach for weeks. This involved creating a star-shaped polymer design with 6 arms that could be folded up into a capsule. The idea being that when the capsule dissolves in the stomach, the arms unravel and the size of the star is wider than the opening between the stomach and the small intestine (5.4cm versus 1.9cm).

They experimented with different molecular compositions to see which would be robust enough to stay in stomach juices for weeks.

They then performed various experiments in the laboratory to determine the best structure for the contraceptive drug levonorgestrel to be slowly released from this drug delivery system.

Finally, the researchers tested the stability of the drug delivery system in 3 pigs. They took X-rays to see if the star stayed in the stomach (they had modified the system so that it contained small metallic beads so it would be seen with X-ray). They also took blood tests to determine the level of levonorgestrel that was released at various times over the month.

What were the basic results?

The drug delivery system was stable in simulated gastric juices for 4 weeks. There was some degradation, but the structure remained intact. The contraceptive drug levonorgestrel was steadily released into the fluid in the laboratory over the 28 days.

When the capsule was given to 3 pigs, X-rays showed the star remained in the stomach for 29 days. During this time, 2 arms in total became detached from the stars and exited their stomach. Various levels of levonorgestrel were detected in blood tests throughout the 29 days.

How did the researchers interpret the results?

The researchers report that "future successful human translation will require further development in dogs and humans".

This will include refinement of the chemical composition of the drug capsule so that it is able to last for 3 weeks in the stomach and release the active form of the drug at a steady rate.

They acknowledge that they will need to test whether the level of drug absorption is high enough to be an effective contraceptive.


This is early-stage research into a new, long-release drug delivery system. There will need to be extensive tests to see if it is safe to have the star-shaped delivery system in the stomach.

It is also not clear how long it might remain in the stomach. At 29 days the star was still in the pigs' stomachs, though the levonorgestrel hormone had nearly been fully absorbed. The researchers are aiming for a capsule that is taken once per month, so presumably they will need to refine the delivery system so that it can be eliminated from the body before the next capsule is taken.

Finally, the researchers will need to work out if enough levonorgestrel can be released to prevent pregnancy, but not so much as to cause unwanted side effects, such as breast pain, feeling or being sick, or dizziness.

If you want to use a long-acting contraceptive, there are several options available now including:

NHS Attribution