Insulin Pills Possible with Nanoshells

Tracy Staedter, Discovery News

Jan. 23, 2007 — Todd Fischer was 18 years old when he found out he had type 1 diabetes. That same day, he began injecting himself with insulin before and after every meal.

"All of a sudden I went from normal teenager to human pincushion, literally overnight," said Fischer, who is now 31 years old.

But thanks to new research, Fischer and other diabetics could soon be relieved of some of the hassles associated with treatment. Researchers have developed a method for loading nano-sized particles with insulin that could one day lead to insulin pills — and with them, the end of needle-based delivery.

For now, Fischer is attached to a beeper-sized insulin pump that delivers a regular, low dose of medicine through an external catheter. But that hasn't made life easier.

"You have to change all the tubing attached to your body every three days [and]...in order to insert the catheter, you use a needle about two-inches long. That's not fun," said Fischer.

Managing the treatment — carrying needles, a cooler for insulin, a blood glucose tester, test strips, extra sugar — can be overwhelming. "The pain becomes the last thing on your mind," he said.

The "oral route is considered to be the most convenient and comfortable means for the administration of insulin," said Hsing-Wen Sung, a professor at the National Tsing Hua University in Hsinchu, Taiwan.

If successful, such a method could also make it possible for patients to take other protein-based drugs orally — for example, calcium regulators for osteoporosis and certain protein-based antibiotics.

Researchers have been trying to produce insulin pills for decades. But so far, production methods require high temperatures and organic solvents that can destroy the protein.

Sung and his team found a way to make tiny insulin-filled particles in a room-temperature solution made mostly of water.

First, the researchers mixed the insulin protein with a negatively charged solution called polyglutamic acid. Next, they prepared a positively charged gel from chitosan, a carbohydrate obtained from shrimp shells. Lastly, the mixed the solution with the chitosan and stirred it at room temperature.

Because opposite charges attract, the chitosan clung to the insulin. The result: nanoparticles with a shell of chitosan filled with insulin.

When given to diabetic rats, the nanoparticles decreased blood glucose level over a period of about 10 hours. In contrast, injections of insulin reduced the blood glucose level quickly, but the effect dissipated after three hours.

"If there becomes a way to give up injections, and the pump and the whole process of maintaining those delivery methods — you could count me in." Fischer said.

Fischer said he would be most concerned with dosage and absorption rates, and wonders if he would be forced into a particular meal schedule. That's "something you don't have to worry about with the pump," he said.

Clinical work will be moving to human trials soon, said Sung, and it's likely that the product would be available for people five years later.

Pictures: DCI | National Tsing Hua University
Source: Discovery News
Editor: Discovery News
Article from Discovery News