Inhaled Insulin: The Power of Powder?

Woman Holding Many Insulin Syringes.
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If you’ve been on injectable insulin for many years and the thought of serially pricking your skin with a needle no longer fazes you, you may be thinking, what’s the big deal about inhaled insulin?

While the newly FDA approved inhaled insulin, Afrezza, is certainly not for everyone, its unique properties may provide advantages for many patients.

A Brief History of Inhaled Insulin

For years, pharma companies pursued an inhaled form of insulin to avoid the need for multiple daily injections.

Their efforts bore fruit in August 2006, when Pfizer introduced Exubera to the market, but it failed to gain traction and was ultimately discontinued in October 2007.  Other pharma companies abandoned their inhaled insulin programs as well.

Recently, however, the FDA approved a new formulation of inhaled insulin, called Afrezza, which was developed by Mannkind and is expected to hit the market in early 2015.

Method of Delivery

While Exubera was administered through a cumbersome device the size of a flashlight, Afrezza uses a technology called the Technosphere in which the insulin is dissolved in dry powder and administered via a thumb-sized inhaler. Once inhaled, the device scatters the insulin deep into the lungs where it liquefies and is absorbed by the bloodstream. It is designed to be taken at mealtimes as an adjunct to long-acting injected insulin.

A potential disadvantage of Afrezza is that it will only be offered in 4 and 8 unit doses, which may prove to be too potent for patients on low doses of inulin and too imprecise for those who need careful dosing.

Rapid Time-to-Peak and Risk of Low Blood Sugar (Hypoglycemia)

From the time of inhalation, insulin levels in the bloodstream peak within 15 minutes. In contrast, injected insulins typically require about an hour to peak. The faster time-to-peak with inhaled insulin obviates the need to administer insulin 15 minutes prior to a meal.

This rapid peak in insulin levels may benefit patients eating high carbohydrate-containing meals but also creates a potential risk of hypoglycemia. However, in a 24-week industry-supported study with over 500 patients with type 1 diabetes, there was actually a significant decrease in hypoglycemic events with Afrezza compared to injected mealtime insulin.

Inhaled Insulin and Blood Glucose Control

While injected insulin remains in the bloodstream for 4 hours, inhaled insulin disappears within 2-3 hours. Hypothetically, the quick clearance of inhaled insulin might be too rapid to tackle the delayed rise in blood glucose often seen after fat-containing meals. However, in the same study cited above, hemoglobin A1C levels were nearly equivalent using injected versus inhaled insulin, and fasting glucose levels were lower with inhaled insulin. Conversely, in other clinical trials with Afrezza, the incidence of diabetic ketoacidosis was 4.8x higher in patients treated with inhaled insulin than with subcutaneous insulin. This suggests that it may be harder to achieve tight glycemic control with inhaled insulin.

Side Effects

Inhaled insulin is contraindicated in patients with active lung cancer, asthma or chronic obstructive pulmonary disease (COPD) due to a dangerous complication called “acute bronchospasm”.

This means that approximately 40% of diabetes patients will be ineligible for inhaled insulin. Even in patients without underlying lung pathology, inhaled insulin commonly causes a dry cough which occurs within seconds to minutes of the inhaled insulin administration. The cough is mild and generally diminishes after the first month of therapy. Post marketing trials will monitor the use of inhaled insulin to look for an increased incidence of lung cancer.

Patient Satisfaction

In terms of overall satisfaction, in short trials of patients with type 1 diabetes using inhaled insulin, there was a significant increase in patient satisfaction (e.g., ease of administration, social comfort, and convenience) with inhaled insulin when compared to the subcutaneous version.

So even if you are a veteran user of injectable insulin therapy, if you are an eligible patient, you might think about trying inhaled insulin when it is once again introduced to the market in 2015. The method of delivery is simple, it appears to be effective, side effects seem to be minimal in appropriate patient, and user satisfaction is high.