New drug-capsule may one day replace insulin injection for diabetics

Sydney, July 22:  Australian scientists have designed a new type of oral capsule that could one day mean pain-free delivery of insulin and other protein drugs.

Thousands of people with diabetes need insulin injections up to several times a day, which can be unpleasant for the patient and results in high healthcare costs. 

According to Dr Jamie Strachan, from RMIT University, the capsule protected the drug inside so that it passed safely through the stomach to the small intestine.

"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 Strachan, from the School of Science.

"We package the insulin inside a fatty nanomaterial within the capsule that helps camouflage the insulin so that it can cross the intestinal walls.

"It's actually similar to how the Pfizer and the Moderna Covid vaccines work where the mRNA in those vaccines is also packaged within fats, helping to keep the drugs active and safe during delivery in the body."

These vaccines contain mRNA, which is similar to DNA, to safely carry the instructions for making a viral protein within the body, activating our immune system. 

Dr Celine Valery, a pharmaceutical scientist from RMIT and study co-author, said they used the same amount of insulin in the oral capsules and in the injection delivery.

The study, published in the international journal Biomaterials Advances, tested the new oral capsule with insulin in a pre-clinical study, which assessed the performance of the oral capsules with both fast-acting and slow-acting insulin.

"When controlling the blood-sugar, you need a very fast response if you're eating a meal. That's known as fast-acting insulin," said said co-lead researcher Professor Charlotte Conn, a biophysical chemist from RMIT University, from the School of Science.

A slow-acting form acts over a much longer timeframe -- up to a day or so -- to keep the insulin in the body steady. Most diabetics take a combination of both types of insulin.

"We had excellent absorption results for the slow-acting form -- about 50 per cent better than injection delivery for the same quantity of insulin,” Conn said.

The capsule achieved good absorption results for fast-acting insulin, but the significant lag in the insulin taking effect compared with injection delivery would likely make it less practical.

"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," Conn said.

"The oral capsules could potentially be designed to allow dosing over specific time periods, similar to injection delivery. We need to investigate this further, develop a way of doing so and undergo rigorous testing as part of future human trials."  

"It's a great starting point but we need to do further trials to develop an alternative, pain-free method for the delivery of insulin and other protein drugs."

The new technology could also be used to deliver orally other protein drugs such as monoclonal antibodies developed to treat inflammatory conditions, cancer and other diseases.