Revolutionizing Insulin: Creating Stable Insulin for Warm Climates

How AC/DC Copolymers can dramatically improve insulin stability and transportation.

Diabetes is a disease where the body’s ability to produce the hormone insulin is impaired, resulting in abnormal metabolism of carbohydrates, and elevated levels of glucose. Insulin is an essential protein drug for over 20 million patients worldwide with type 1 diabetes. While insulin formulations have advanced tremendously, many formulations can not tolerate warm climates and lose their chemical identity as a result. Many people who experience diabetic issues reside in warm regions. In order to provide insulin for these patients, insulin must be carefully refrigerated and transported for an extended period of time. The process of transporting mass amounts of insulin is difficult and costly as machinery can often fail, or mishaps can occur due to the insulin not being properly stored. Currently, the process of transporting commercial insulin formulations takes two weeks, meaning that insulin is not always accessible, and patients in desperate need may not always receive it. Over 15 billion dollars have been allocated to pay for the refrigerated transport of these complex medicines, and over 35 billion dollars are lost annually as a result of numerous failures during the transport process.

Caitlin L. Maikawa and her team published an article discussing their discoveries of a new insulin formulation involving the usage of a class of copolymers (two or more different types of monomers linked in the same polymer chain) consisting of water-soluble and hydrophobic monomers named AC/DC. These copolymers could enable the development of ultrafast insulin formulations and improve the stability of current formulations, resulting in a lessened reliance on cold chain transportation and the economic losses that occurred from that method. The copolymers would act as a single “drop-in” vehicle to stabilize commercial insulin formulations, marking an important step in improving global access to critical medical drugs.

To test this new solution, 16 diabetic rats were fasted for 4 to 6 hours and were either placed in the Humulin control group or Humulin + AC/DC excipient (MoNi23%). These rats were given Humulin formulations that were all prepared at staggered times. Before injection, baseline blood glucose was measured, and the blood was sampled every 30 minutes for 5 hours following injection. The maximum change in blood glucose was measured from the baseline and used as a metric of the bioactivity of each formulation. This data would be later used to assess vivo bioactivity after aging. Another group of 16 rats were fasted for 4-6 hours and were placed in either a Humulin or Humulin + AC/DC excipient. These rats received either six-month-aged Humulin formulation or fresh formulations. Following injection, the blood was sampled every 15 minutes for 2 hours. The top three formulas that were best able to stabilize the insulin in the rats were selected and further tested on their long-term stability. The team concluded that formulations stabilized with the AC/DC excipient exhibited no changes in their secondary structure after stressed aging, meaning that these formulas can successfully maintain low insulin levels.