Products
An inhalable insulin preparation containing a rapid-acting human insulin was approved in the United States in 2014 (Afrezza, powder inhalation). The drug has not yet been registered in many countries. Pfizer’s first inhalable insulin Exubera was withdrawn from the market in 2007 for commercial reasons; see Exubera.
Structure and properties
Human insulin (C257H383N65O77S6, Mr = 5808 g/mol) is a polypeptide with the structure of the antidiabetic hormone produced by the pancreas in humans. The peptide consists of two chains with a total of 51 amino acids. The A chain is composed of 21 amino acids and the B chain is composed of 30 amino acids. Insulin has two disulfide bridges connecting the chains and one disulfide chain within the A chain. Insulin is adsorbed in the drug to micrometer-sized carrier particles consisting of fumaryldiketopiperazine (FDKP). In the lungs, the microparticles dissolve at a neutral to basic pH, releasing the insulin into the bloodstream. The carrier molecules are excreted unchanged by the kidney.
Effects
Human insulin (ATC A10AF01) has blood glucose-lowering and antidiabetic properties. It promotes the absorption of blood glucose into tissues (e.g., muscle, adipose tissue) and inhibits glucose formation in the liver. The effects are based on binding to insulin receptors.
Indications
For the treatment of diabetes mellitus.
Dosage
According to the SmPC. The insulin is inhaled at the beginning of a meal. It is not a substitute for long-acting insulin in the treatment of type 1 diabetes.
Contraindications
The drug is contraindicated in hypersensitivity, hypoglycemia, and chronic lung disease such as asthma and COPD because of the risk for bronchospasm. Full details of precautions and interactions can be found in the drug label.
Adverse effects
The most common potential adverse effects include hypoglycemia, cough, sore throat, and throat irritation. Pre-existing pulmonary disease is at risk for the development of bronchospasm.
