Inhaled Insulin for Diabetes Mellitus

Tarun K. Mandal


Am J Health Syst Pharm. 2005;62(13):1359-1364. 

In This Article


The pulmonary delivery of insulin may reduce the need for multiple daily subcutaneous injections of insulin for many patients with diabetes. The lungs are an attractive site for delivery of insulin because they are permeable to proteins and offer a large surface area for drug absorption. Several pulmonary insulin delivery systems are currently under development.

When systemic absorption is desired, deposition of drug into the alveolar region of the respiratory tract is necessary. A challenge of pulmonary drug delivery is the lack of reproducibility of the drug deposition site within the respiratory tract. Factors influencing the deposition site of drugs within the respiratory tract include the mode of inhalation and the physical properties of the aerosol.

The pharmacokinetic profile of inhaled insulin has both advantages and disadvantages compared with subcutaneous insulin injection. Because inhaled insulin is more quickly absorbed, pulmonary insulin delivery may reduce the time necessary between insulin administration and mealtimes. However, because the duration of action of inhaled regular insulin is short, a once-daily injection of long-acting insulin should be administered to patients who previously required multiple insulin injections daily. The bioavailability of inhaled insulin is less than 20%; thus, dosage requirements and cost per treatment are increased in comparison with insulin administered by subcutaneous injection.

The long-term effects of intraalveolar insulin deposition and immunogenic safety of inhaled insulin have not been fully elucidated. Patient acceptance and compliance with insulin therapy may be enhanced by the availability of inhaled insulin.