CIMIT Summer Education Series 2009: Frontiers of Inhalation Technologies in Biomedical Sciences and Clinical Medicine

7.7.2009 Inhalation Technology Fundamentals: Systemic Delivery of Proteins via the Lungs: Setbacks and Advances SPEAKER: Joseph Brain, SD: Harvard School of Public Health MODERATOR: Jose Venegas, PHD: HMS, MGH

Forum Summary

The delivery of drugs to and through the lungs is a concept that has been around for a long time, but so far, the potential of this route of drug delivery has not been fully realized.  Many peptides and protein hormones can be administered via the lungs because the lungs provide a large surface area with few proteases and a thin barrier between air and blood.  Proteins are believed to pass through this barrier of epithelial and endothelial cells by going between cells and via vesicular transport. 

Recent attempts to deliver aerosolized insulin to patients with diabetes highlight some of the advantages and disadvantages of inhalation technology.  In the early part of this decade, a number of companies were extremely interested in inhalable insulin, which promised to allow patients with diabetes to control their blood sugar without subcutaneous injections.  Pfizer eventually took the lead in this field and spent three billion dollars to develop and test a delivery platform for aerosolized insulin.  Their system, known as Exubera, was approved for use in adult patients with type-1 and type-2 diabetes in early 2006, but in late 2007, Pfizer announced that Exubera would no longer be made available, even though aerosolized insulin was as good at controlling hyperglycemia as subcutaneous insulin and seemed to be preferred by many patients.  After Pfizer pulled the plug on Exubera, most other companies researching inhalable insulin abandoned their efforts.

Important lessons can be learned from the failure of Exubera.  The delivery system developed by Pfizer cost more than existing methods for treating diabetes, and Pfizer did not demonstrate that its product was better than existing products.  Thus, insurers were reluctant to pay for Exubera.  Many physicians were hesitant to recommend Exubera to patients because Exubera was shown to cause modest, reversible declines in pulmonary function.  Aersolized insulin may be easier for many diabetic patients to use than other means of controlling blood sugar, but the fact that Pfizer never demonstrated the superiority of its product eventually contributed to Exubera’s downfall.

In the future, inhalation technology will hopefully be used to improve the way in which many diseases are treated.  Many types of pharmaceutically active molecules can be delivered relatively easily through the lungs.  Demonstrating the superiority of new products, not just their non-inferiority, will be highly important for companies seeking to develop inhalable drugs.               

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