A shot a month

MANY diabetics go through the pain of injecting themselves with insulin at least twice a day.

The number of times they need to prick themselves to manage their blood sugar level can go up to 120 a month. The fear of pricking themselves often leads to noncompliance, making patients prone to complication of the heart, eye and kidney. Scientists from National Institute of the Immunology (NII) in New Delhi have developed a novel form of insulin whose single shot can keep the blood sugar level under control for over a month.

Insulin is a protein produced in the pancreas as a hexamer, or a unit of six molecules. When it is released into the blood and used by the body, hexamer separates into active monomers or single insulin molecules. Monomers can assimilate quickly in the body but are unstable and quickly degraded by the proteases (protein degrading enzymes). Hexamer is a stable form of insulin and is desirable for making drugs. But it remains active for only 24 hours.

Using protein folding techniques, the team developed a safe and long-lasting molecular assembly, the Supra- Molecular Insulin Assembly II (SIA-II), which exhibits controlled and sustained release of monomers for a long time, the scientists said in the July 13 issue of PNAS. They studied its efficacy on diabetic rats and mice.

Results revealed slow and sustained release of insulin from SIA-II that regulated blood sugar levels in the diabetic animals. The glucose level remained normal for over 120 days when injected with bovine insulin and for 140 days when given shots of human recombinant insulin. “No chemical modification or additives have been added for its preparation. The protein has been coaxed into forming an oligomer (a unit of over six monomers),” said Avadhesha Surolia, director of NII. The scientists have patented the technology. SIA-II could be a relief for poor patients as they would have to buy a single dose instead of 30 doses a month, said Ambrish Mithal, senior endocrinology consultant with Indraprastha Apollo Hospitals in New Delhi.

The drug may take several years to reach the market. “Its safety remains to be established,” said Anoop Misra, head of the diabetes department of Fortis Hospital in New Delhi. Patients who need insulin instantly may still need booster shots with rapid acting insulin, he said. That is because, oligomers take time to separate into active monomers.

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