A drug-carrying capsule with a motor protects medicines from stomach acid and enzymes before releasing them in the small intestine
28 September 2022
To be absorbed into the bloodstream, drugs taken orally have to survive harsh stomach acid and enzymes, as well as manoeuvre through bacteria and mucus in the intestine, which can rule out many sensitive drugs from being taken this way. Only 1 per cent of insulin, for example, is taken up by the body when it is swallowed because stomach enzymes break it down, so people with diabetes have to take injections instead.
Shriya Srinivasan at the Massachusetts Institute of Technology and her colleagues have developed a drug-carrying capsule called RoboCap that can drill through mucus in the lower intestine and disperse its load. “I was watching videos of these machines that can make tunnels and I thought, ‘OK, what if we did this but for mucus,’” she says.
The pill is 2.5-centimetres long and 1-centimetre wide – about the size of a large multivitamin – and encased in a gelatin capsule that dissolves in stomach acid. The pH in the lower intestine activates the motor, which is powered by a small battery. The pill has fins and studs on its surface, which help to wick away and scrape at mucus. Once it has tunnelled far enough, the drug is released and mixed further by the pill’s movement.
Srinivasan and her colleagues tested RoboCap’s ability to deliver insulin in seven live pigs, comparing it with insulin delivered into the gut through a tube. They found that RoboCap increased the amount of drug absorbed by 20 to 40 per cent and lowered blood sugar compared with the control group.
“RoboCap is an innovative concept that aims to overcome the current difficulty in orally delivering many advanced and emerging therapies, such as peptides, proteins and nucleic acids,” says Abdul Basit at University College London.
While the results are promising, more work needs to be done to examine how people with weakened immune systems might be affected, says Basit, as well as the pill’s effect on beneficial bacteria that reside in the mucus.
Journal reference: Science Robotics, DOI: 10.1126/scirobotics.abp9066