Australian scientists have designed a new capsule that could mean diabetics might one day swallow their insulin instead of injecting it. The design also has potential uses for delivering other protein drugs, such as antibiotics and cancer treatments.
Type 1 diabetes is an autoimmune disease where the body’s immune system attacks the insulin-producing beta cells of the pancreas, causing little to no insulin to be secreted. Type 1 diabetics – and some type 2 diabetics – therefore have to inject themselves with insulin several times a day.
Many diabetics take two types of insulin: fast-acting and slow-acting. After it’s injected, fast-acting insulin is absorbed quickly and is used to control blood glucose levels during meals and snacks and to correct high blood glucose. Meanwhile, long-acting insulin is usually administered once a day. It’s absorbed slowly and provides a ‘background’ level of insulin to help control blood glucose over the day.
A team of scientists from RMIT University in Melbourne, Australia, has developed a new oral capsule able to deliver insulin that has shown promise as a new way of administering the drug.
Insulin is made of smaller versions of proteins called peptides. Previous attempts to develop an orally administered insulin have found that the severe pH levels in the gastrointestinal tract degrade the peptides, causing the drug to lose its function. Other protein drugs run into the same difficulty.
To get around this problem, the scientists encapsulated the insulin in a lipid-based nanomaterial placed inside an enteric capsule. The enteric capsule’s polymeric coating protects against the low pH (high acidity) of the stomach.
“The capsule has a special coating designed to not break down in the low pH environment of the stomach, before the higher pH levels in the small intestine trigger the capsule to dissolve,” said Jamie Strachan, lead author of the study. “We package the insulin inside a fatty nanomaterial within the capsule that helps camouflage the insulin so that it can cross the intestinal walls.”
The scientists tested the capsule’s performance in animal studies using fast- and slow-acting insulin.
While the fast-acting insulin capsule was well absorbed, there was a significant lag in the time it took for the insulin to take effect compared with delivery by injection, making it impractical. More promising results were achieved using the slow-acting insulin capsule.
“We had excellent absorption results for the slow-acting form – about 50% better than injection delivery for the same quantity of insulin,” said Charlotte Conn, corresponding author of the study. “Our results show there is real promise for using these oral capsules for slow-acting insulin, which diabetics could one day take in addition to having fast-acting insulin injections.”
The scientists say their capsule design is “a promising starting point” for the non-invasive delivery of insulin and could be used to deliver other protein drugs, such as antibiotics or monoclonal antibodies used to treat cancer.
They plan to improve the design, to develop a way of dosing over specific time periods before moving on to human trials.
The study was published in the journal Biomaterials Advances.
Source: RMIT University
