Inhalable insulin

Inhalable insulin is a powdered form of insulin, delivered with an inhaler into the lungs where it is absorbed.[1] In general, inhaled insulins have been more rapidly absorbed than subcutaneous injected insulin, with faster peak concentration in serum and more rapid metabolism.[2]

Exubera, developed by Inhale Therapeutics (later named Nektar Therapeutics), became the first inhaled insulin product to be marketed, in 2006 by Pfizer, but poor sales led Pfizer to withdraw it in 2007. Afrezza, a monomeric inhaled, ultra rapid-acting insulin developed by Mannkind, was approved by the FDA in 2014 and is the only inhaled insulin commercialized at the moment.[3]

History

Insulin was discovered by Sir Frederick G Banting, Charles H Best, and JJR Macleod from the University of Toronto in 1921 as an injectable agent.[4] German researchers first introduced the idea of inhalable insulin in 1924. Years of failure followed until scientists realized they might be able to use new technologies to turn insulin into a concentrated powder with particles sized for inhalation.

In the 1980s Nektar Therapeutics, based on work by A. Carl Leopold on vitrifying proteins, developed technology to make insulin into small particles, technology then licensed to Pfizer. Alkermes developed a delivery device that they licensed to Eli Lilly and Company.

Once concrete methods were developed, human tests began in the late 1990s. In January 2006, the U.S. Food and Drug Administration (FDA) approved the use of Exubera, a form of inhalable insulin developed by Pfizer. It was approved in the UK in August 2006 but reimbursed by the National Health Service only for people who had problems with needles.[5] It was not reimbursed by any US insurer.