Sue Marshall blogs about diabetes for Desang

Powdered human recombinant insulin | January 5, 2010

From Diabetes Health: “The enthusiasm for inhaled insulin has waned, to say the least, since Exubera was pulled off the market by Pfizer. Following the Exubera debacle, the development of two other inhaled insulins (AIR by Eli Lilly and Alkermes, and AERx by Novo Nordisk) was halted as well.

But please don’t consider that the final word on inhaled insulin. There’s a new product in Phase III clinical studies, called Afresa, and it may succeed where the others failed. The reason, says its developer, MannKind Corporation, is that it simply mimics the functioning of natural insulin better than injectable insulins. The fact that it happens to be inhaled is just a side convenience, whereas for Exubera, that was the whole point.

Afresa consists of “Technosphere” particles, which are tiny lattices of crystals that form spontaneously from a liquid, but only under acid conditions (pH below 7). Powdered human recombinant insulin is attached to the lattices electrostatically, after which the particles are dried to a powder and loaded into a inhaler device. When the particles are inhaled into the lungs, they encounter a basic (alkali) environment (pH of 7.3 or 7.4), which causes them to dissolve instantly back into a liquid. The released insulin is then transported from the lung alveoli to adjacent capillaries, sending the insulin to the bloodstream very, very rapidly. The remaining liquid is simply voided from the body.

What’s critical here is the fact that peak insulin levels are achieved within 12 to 14 minutes after inhalation. This rapid insulin spike, which mimics the natural insulin spike in response to a meal, is what signals the liver to stop releasing glucose during the meal-time period. Even rapid-acting insulin analogs take 30 to 60 minutes just to begin acting after injection, and they typically peak at four hours. Consequently, there is no quick spike to send the signal to the liver, and endogenous glucose production by the liver is suppressed much more slowly.”


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