Diabetes is a severe but controllable disease that affects many people. It is estimated that 20.8 million people in the U.S. had diabetes in 2005, while only 14.6 million of those were diagnosed. That makes up about 7% of the population. Approximately 1.5 million new cases of diabetes were found in 2005 in people over the age 20, most of whom were between the age of 40 and 59 years. In 2002, diabetes was the sixth leading cause of death with a total of 224,092 people dying due to the disease. The total estimated cost of having diabetes in the U.S. was about $92 billion in medical costs and another $40 billion due to indirect costs such as disability, work loss, and premature mortality.

Glycemic control, assessed by blood glucose levels and hemoglobin A1C (A1C), is important in the treatment of all types of diabetes. With the finding that intensive glycemic control with the use of insulin decreases the complications associated with diabetes, other routes of insulin administration have been studied instead of the subcutaneous injections currently available. Pfizer set out to create an oral insulin human [rDNA] inhalation powder called Exubera®. In association with Nektar Therapeutics, they developed an inhaler to deliver insulin into the lungs. This device uses blister packs of 1 or 3 mg; each mg is equivalent to 2.5 to 3 units of insulin. A study measuring the time-action profile of Exubera® was completed. It was found that the onset of action was similar to rapid-acting insulin analogs and had a duration similar to regular insulin. Exubera® appears to be usable as a short-acting pre-meal insulin to help control blood glucose levels in the treatment of diabetes.

Selected studies show that rapid-acting, dry-powder inhaled insulin, Exubera®, is safe and effective as pre-meal treatment in select type 1 and type 2 diabetes. These results coincide with the results of previous preliminary studies with Exubera®. Other studies have been conducted assessing satisfaction with the use of inhaled insulin as opposed to injecting insulin. All studies showed that patients were more satisfied with the use of inhaled insulin as compared to subcutaneous insulin. The results of one study showed that patients with type 2 diabetes were more willing to start insulin therapy with Exubera® than subcutaneous insulin.

Exubera® has been approved by the FDA for the treatment of both type 1 and type 2 diabetes. An FDA approved Medication Guide will be required to accompany the inhaler when it is dispensed. Exubera® cannot be used in current smokers or those who have smoked within the previous 6 months due to changes in absorption of the insulin. It is also not recommended in patients with lung problems such as asthma, bronchitis, or emphysema. Lung function tests will be required at the beginning of treatment and every 6 to 12 months throughout treatment.

The most common side effects of Exubera® were similar to normal insulin with increased chances of hypoglycemia and weight gain. Patients in clinical studies also experienced a cough but it was usually mild and decreased in severity over time. The long term effects of inhaled insulin are currently unknown, although studies are being conducted to determine these effects.

The inhaler device is manually pumped to produce a cloud of insulin into a chamber which is then inhaled through the mouthpiece. The inhaler, when closed, is about the size of an eyeglass case that measures 6.5 inches in length and is opened to be used at a length of about 11 inches. The cost has not yet been determined, however it will probably be much more expensive than current insulin products.

Exubera® appears to be an innovative inhaled insulin device that will prove itself to be very useful in a select population. It will not be appropriate for all patients with diabetes but may serve to be very helpful in patients with an overwhelming fear of needles. Future technology may improve upon the idea of inhaled insulin and possibly remove any need for injections ever again.

For more information on Exubera® and its clinical studies, please contact Andy Howells Pharm.D. candidate at Ferris State University.