Preparations

There are several types of insulin preparation:

• very rapidly-acting insulin
• short-acting
• medium-acting and long-acting insulin
• insulin mixes

Inhaled insulin (1):

• is available as a rapid acting insulin; studies in people with type 1 diabetes suggest rapid pharmacokinetics
• pilot study found evidence that compared with injectable rapid-acting insulin, supplemental doses of inhaled insulin taken based on postprandial glucose levels may improve blood glucose management without additional hypoglycemia or weight gain (1)
  • although results from a larger study are needed for confirmation
    
    
• Exubera, an inhaled form of rapid acting insulin developed by Pfizer, became the first inhaled insulin product to be marketed in 2006 (2)
  • but poor sales led Pfizer to withdraw it in 2007
  • Afrezza developed by Mannkind, that uses a different technology (technosphere) was approved by the FDA in 2014
    • technosphere technology (2):
      • contains recombinant human insulin dissolved with powder (fumaryl diketopiperazine)
      • once inhaled, technosphere insulin is rapidly absorbed upon contact with lung surface
      • inhalable insulin is delivered with a thumb size inhaler with a rather increased dosing flexibility
      • both components, insulin and powder (fumaryl diketopiperazine) are almost completely cleared from the lungs of healthy individuals within 12 hours of inhalation. In contrast to Exubera (8-9%) only 0.3% of insulin of inhaled insulin remained in lungs after 12 hours
    • FDA approved Afrezza with a caution (Risk Evaluation and Mitigation Strategy) for a communication plan to inform health care professionals about the serious risk of acute bronchospasm associated with Afrezza

Reference:

• ADA. Pharmacologic Approaches to Glycemic Treatment: Standards of Medical Care in Diabetes 2021. Diabetes Care 2021;44(Suppl. 1):S111-S124
• Mohanty RR, Das S. Inhaled Insulin - Current Direction of Insulin Research. J Clin Diagn Res. 2017;11(4):OE01-OE02. doi:10.7860/JCDR/2017/23626.9732