Evolution of a Pulmonary Insulin Delivery System ( Exubera) for Patients With Diabetes

Priscilla A. Hollander, MD


March 05, 2007

Pulmonary Delivery as a Route for Insulin Administration

Since the discovery of insulin over 80 years ago, investigators have sought to develop a pulmonary route of insulin delivery. The pulmonary route of administration offers several advantages. First, the lung has a large surface area for drug absorption, ranging from 100 to 140 m2.[9,10] In addition, the alveolar epithelium has permeability that allows for rapid absorption of solutes. Because the mucociliary clearance of the alveolar lung tissue is slower than that of the bronchiolar tissues, the alveoli provide a greater opportunity for the absorption of larger molecules (eg, insulin).[9]

Studies have shown that particle size should be between 1 and 3 micrometers (mcm) in diameter for optimal deposition in the lung, and that dry powder formulations can deliver more active drug in a single inhalation than liquid aerosol formulations.[11] Patient-controlled variables (eg, inhalation flow rate, inhaled volume, and duration of inhalation) also need to be controlled for optimal deep-lung insulin delivery.[9,10,11]

Although several inhaled insulin devices are in various stages of development, the Exubera (Pfizer, New York, NY) formulation and delivery system is the first inhaled insulin to be approved for use in the United States and in Europe. Additional agents in phase 2 and 3 of development include the Technosphere Insulin (TI) System (MannKind Corporation, Valencia, California), the Lilly/Alkermes inhaled insulin system, and the AERx insulin Diabetes Management System (AERx iDMS; Novo Nordisk).


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