Background: Inhaled dry powder insulin (IDPI) is the first inhaled insulin approved for the treatment of type 1 and type 2 diabetes mellitus (DM).
Objective: This article reviews available information on IDPI, focusing on its clinical pharmacokinetics, comparative efficacy, tolerability, adverse events, dosage and administration, and cost.
Methods: MEDLINE (1966-July 2006) and Web of Science (1995-July 2006) were searched for original research and review articles published in English. The search terms used were inhaled insulin, inhaled human insulin, rDNA origin inhalation powder, inbaled dry powder insulin, and IDPI. All published comparative efficacy studies were included in the review, as well as selected information from the package insert for IDPI.
Results: IDPI is an inhaled dry powder form of regular human insulin (RHI) that is used as a premeal insulin to improve glycemic control by reducing postprandial glucose excursions. The literature search identified 5 efficacy trials comparing reductions in glycosylated hemoglobin (HbA(1c)) in a total of 582 patients with type 1 DM who received either premeal IDPI plus neutral protamine Hagedorn (NPH) or Ultralente insulin or injectable RHI plus NPH or Ultralente insulin. The search identified 5 comparative efficacy studies of IDPI monotherapy or the addition of IDPI to the current regimen in a total of 1413 patients with type 2 DM that was uncontrolled with diet and exercise, metformin, a sulfonylurea, metformin and a sulfonylurea, or a secretagogue plus an insulin sensitizer. The use of IDPI as a mealtime insulin in these studies was associated with absolute changes in HbA(1c) ranging from -0.6% to +0.1% in patients with type 1 DM and from -1.4% to -2.9% in patients with type 2 DM. HbA(1c) values <7% were achieved in 16.9% to 28.2% of patients with type 1 DM and 16.7% to 44.0% of patients with type 2 DM. The most common nonrespiratory adverse event noted during clinical trials of IDPI was hypoglycemia (type 1 DM: 8.6-9.3 episodes/subject-month; type 2 DM: 0.3-1.4 episodes/subject-month), and the most common adverse event involving the pulmonary system was cough (21.9%-29.5%).
Conclusions: IDPI is the first available inhaled insulin. It provides an additional option for the achievement of HbA(1c) goals with a premeal insulin.