Advances in Pulmonary Drug Delivery

The FDA approval of Pfizer's Exubera (insulin human [rDNA origin]) inhalation powder in January 2006 was a notable milestone in the history of drug delivery systems. Through the use of the pulmonary drug delivery route, this product is the first inhaled and noninjectable insulin option in the United States since the introduction of insulin more than 80 years ago.¹ The approval of Exubera has revolutionized the drug delivery industry and provided the health care industry with the potential for unlimited possibilities for providing drug therapy via the pulmonary drug delivery route.

This new capability broadens the realm of possibilities for investigating the potential to provide safe drug delivery via the pulmonary route. Various areas of medicine may benefit, such as diabetes treatment, pain management, oncology, osteoporosis, migraines, immunosuppression, and neurologic disorders.² The advantages of utilizing pulmonary drug delivery include the large surface area available for drug absorption and also rapid absorption through the alveolar epithelium.³

Exubera

Exubera is manufacturered by Pfizer Pharmaceuticals. Nektar Therapeutics developed the inhaler device to be used with Exubera. The product is approved for use in adults with type 1 and type 2 diabetes for the control of hyperglycemia. For individuals with type 1 diabetes, Exubera should be used in regimens that include longer-acting insulin. For those with type 2 diabetes, it may be used as a monotherapy or with oral diabetic agents or longer-acting insulins.^1,4

In the development of the drug delivery device, Nektar Therapeutics incorporated several unique features. They confirmed that the lungs were the most effective route for administration due to the large surface area of the alveoli when the lungs are expanded. In order to take advantage of the pulmonary delivery route, the most appropriate drug particle size was formulated for the best possible absorption by the lungs. A unique method of protecting the powder insulin from moisture prior to use was also developed. In addition, the design of the inhaler device needed to be effective in delivering a high concentration of insulin to the lungs for a variety of people, with little or no waste and with only one puff.⁵

Exubera is available in 1-and 3-mg unit-dose blisters that are inserted in the handheld inhalation device. The sealed blister powders remain protected and moisture-free for up to 2 years. Exubera should be administered 10 minutes before meals using a combination of 1-and 3-mg unit doses. Common adverse events include hypoglycemia, dyspnea, cough, sore throat, and dry mouth. The manufacturer recommends that Exubera should not be used by individuals with a history of smoking or those who stopped smoking within a 6-month time frame. To reduce the risk of hypoglycemia, therapy should be discontinued if the patient resumes smoking. The use of this product also is not recommended for those with chronic lung disease.^1,4 Patients should have a baseline assessment of lung function prior to initiation of therapy, 6 months after initiation of therapy, and then annually.

Conclusion

As advances in technology emerge, more opportunities arise to assist health care professionals with more productive ways of providing better care to patients by exploring other options for drug delivery. The formulation of various innovative drug delivery systems is a prospering industry in the United States. Other insulin inhalation products under development by pharmaceutical companies include AERx by Aradigm/Novo Nordisk; AIR Insulin by Alkermes/Eli Lilly; Metered-dose Inhaler by Kos Pharmaceuticals Inc; and Technosphere Insulin System by Mann- Kind Corp.²

The approval of agents such as Exubera brings hope to many patients with diabetes and may aid in better management of diabetes as well as increased patient compliance. Furthermore, through these new developments, the pulmonary route of drug delivery may indeed be beneficial to a host of patients afflicted with many other systemic diseases.

For more information on Nektar Therapeutics products, visit its Web site at www.nektar.com. For more information on Exubera, visit www.exubera.com.

Ms. Terrie is a clinical pharmacy writer based in Haymarket,Va.

For a list of references, send a stamped, self-addressed envelope to: References Department, Attn. A. Rybovic, Pharmacy Times, Ascend Media Healthcare, 103 College Road East, Princeton, NJ 08540; or send an email request to: arybovic@ascendmedia.com