To test the capsule’s real-world applications, the team used both mathematical modelling and animal models to investigate the effects of delivering a sustained therapeutic dose of a drug called ivermectin, which is used to treat parasitic infections such as river blindness.
Ivermectin has an added bonus of helping keep malaria-carrying mosquito populations at bay.
The team found that in large animal models, the capsule safely stayed in the stomach, slowly releasing the drug for up to 14 days, and potentially providing a new way to combat malaria and other infectious diseases.
The results of this work are published in Science Translational Medicine.
“We want to make it as easy as possible for people to take their medications over a sustained period of time.
When patients have to remember to take a drug everyday or multiple times a day, we start to see less and less adherence to the regimen.
Being able to swallow a capsule once a week or once a month could change the way we think about delivering medications,” said co-corresponding author C Giovanni Traverso, a gastroenterologist and biomedical engineer in the Division of Gastroenterology at BWH and an instructor of medicine at Harvard Medical School.
Medication non-adherence is a massive problem globally.
Medication non-adherence is also a persistent problem in low-resource settings, where there may not be reliable access to health care and the full course of a medication.
To help develop a new solution, the multi-disciplinary research team included members with expertise in biomechanical engineering, pharmaceutical sciences, infectious disease modelling, polymer chemistry and health care innovation.
The research team developed a capsule that is about the size of a fish oil capsule when swallowed.
Once inside the stomach, the capsule unfolds into a star-shaped structure too large to pass through the pylorus and exit the stomach, but designed to allow food to continue passing through the digestive system.
“Some of the challenges we face in getting the capsule in place are the ‘ship in the bottle problem’ – in this case, the neck of the bottle is the esophagus – and preventing the capsule from passing through the rest of the tube,” said Traverso.
“The pylorus is about 2 centimetres in diameter so we designed our system to be 4 centimetres when it opens.
” The capsule contains polymers and other materials mixed with ivermectin to allow the drug to slowly diffuse out of the material over two weeks.
The team reports evidence of diffusion for up to two weeks, and is interested in continuing to develop the system so that it can provide the drug for one month or longer.
Ivermectin is currently used to combat several kinds of parasites, including the parasitic worms that causes river blindness and lymphatic filariasis.
The scientists who discovered ivermectin were awarded the Nobel prize in 2015.
Ivermectin has also been shown to reduce malaria transmission as the drug is toxic to the mosquito species that spread malaria (Anopheles).
The concentrations of ivermectin in the blood of humans taking the drug are high enough to kill mosquitoes that bite them.