MIT engineers have developed a new way to deliver drugs that could last for months—or even years—with just one small injection.
This exciting invention could help people avoid frequent injections, especially for treatments like birth control or long-term medications.
The new method involves injecting tiny crystals of medicine suspended in a liquid.
Once the liquid is injected under the skin, the crystals gather together to form a small, solid “depot” or drug storehouse. From there, the medicine slowly releases into the body over time.
“This system lets us deliver steady doses of medicine for several months or possibly years, using a small needle that’s easy for patients to tolerate,” says Professor Giovanni Traverso, one of the lead researchers.
He teaches engineering at MIT and is also a doctor at Brigham and Women’s Hospital in Boston.
The team published their findings in Nature Chemical Engineering.
The main authors of the paper include Vivian Feig (now a professor at Stanford), MIT graduate student Sanghyun Park, and Pier Rivano, a former visiting researcher.
The project originally focused on improving access to birth control, especially in developing countries. The goal was to make options that are easy to use, last a long time, and can be given without surgery or special tools.
“There are already injectable birth control methods available,” explains Feig, “but they usually only last about three months because the drug spreads out in the body too quickly.”
Some newer methods can last longer but require thick solutions with a lot of extra material called polymers. These can be painful to inject and hard to work with.
The MIT team wanted to create something that could be injected with a fine needle, last at least six months, and not require large amounts of extra material. They chose a birth control drug called levonorgestrel, which forms crystals easily.
When the drug crystals were suspended in a special liquid called benzyl benzoate, they formed a compact depot under the skin after injection. This depot could hold the drug in place and slowly release it. Because the liquid doesn’t mix well with body fluids, it helps the drug stay together in one place.
To adjust how fast the drug is released, the researchers added a tiny amount of a biodegradable polymer called polycaprolactone—less than 2% of the mixture. This made it possible to fine-tune the drug release rate while still keeping the injection simple.
In tests with rats, the researchers found that the depot stayed stable and continued to release medicine for at least three months. Even after that time, 85% of the drug was still present, suggesting it could keep working for much longer.
The depot is also small enough to be removed with surgery if needed.
In the future, this method might be used for more than just birth control. The team believes it could also help deliver long-term treatments for diseases like HIV, tuberculosis, or mental health conditions. They are now working on studies to see how well this system works in human-like skin.
“This system is simple—just a drug, a liquid, and a tiny bit of polymer,” Traverso says. “Now we’re looking into which treatments to focus on first for use in people.”
Source: MIT.
