Inhaled insulin is a needle-free method for managing mealtime blood sugar levels. It is a dry powder breathed in using a specific inhaler, delivering insulin through the lungs. Once inhaled, the fine particles dissolve and are rapidly absorbed into the bloodstream. This allows for quick action to control the rise in blood glucose after eating.
Afrezza: The Current Inhaled Insulin
The only inhaled insulin product currently available is Afrezza, manufactured by the MannKind Corporation. It is an ultra-rapid-acting insulin where human insulin is adsorbed onto carrier particles. These particles are packaged as a dry powder in single-use cartridges.
A patient administers the dose using a small, whistle-sized device called the Dreamboat inhaler. When the patient inhales, the airflow aerosolizes the powder, which travels deep into the lungs. The particles dissolve almost instantly, allowing the insulin to be rapidly absorbed. This process results in a peak insulin concentration within about 15 minutes, which is faster than traditional rapid-acting insulin injections.
Afrezza’s duration of action is also shorter, which can reduce the risk of later-onset hypoglycemia compared to some injectable insulins. The carrier particles are cleared from the body without being metabolized. This combination of rapid onset and short duration mimics the body’s natural mealtime insulin response.
Exubera: The Predecessor
Before Afrezza, the first inhaled insulin approved by the FDA in 2006 was Exubera, developed by Pfizer. It was a dry powder formulation of regular human insulin for adults with both type 1 and type 2 diabetes. Exubera was withdrawn from the market in 2007, just over a year after its launch.
Its commercial failure was due to practical and financial issues. The inhaler device was large and cumbersome, often compared to the size of a telescope, making it inconvenient for patients. Dosing was also considered complex. These factors, combined with its high cost and low adoption rate, led Pfizer to discontinue the product.
Patient Suitability and Contraindications
Inhaled insulin is approved for adults with either Type 1 or Type 2 diabetes to manage mealtime blood sugar. The medication carries a boxed warning for the risk of acute bronchospasm in patients with chronic lung disease. It is therefore contraindicated for individuals with conditions like asthma or chronic obstructive pulmonary disease (COPD).
Smokers or those who have recently quit smoking should not use inhaled insulin due to unpredictable absorption and increased health risks. Before starting therapy, all patients must undergo a lung function test called spirometry. This test establishes a baseline and is repeated after the first six months of treatment and then annually to monitor lung function.
The most frequent side effect is a mild and transient cough, which often occurs immediately after inhalation. Other reported side effects include throat pain or irritation. While hypoglycemia is a risk with all insulins, the frequency of mild to moderate hypoglycemia with Afrezza may be higher, though severe events are not significantly different from some injectable insulins.