indication

For the treatment of type I and II diabetes mellitus.

pharmacology

Insulin is used in the treatment of type I and type II diabetes. The primary activity of insulin is the regulation of glucose metabolism. In muscle and other tissues (except the brain), insulin causes rapid transport of glucose and amino acids intracellularly. It also promotes anabolism, and inhibits protein catabolism. In the liver, insulin promotes the uptake and storage of glucose in the form of glycogen, inhibits gluconeogenesis, and promotes the conversion of excess glucose into fat.

mechanism of action

Insulin binds to the insulin receptor (IR), a heterotetrameric protein consisting of two extracellular alpha units and two transmembrane beta units. The binding of insulin to the alpha subunit of IR stimulates the tyrosine kinase activity intrinsic to the beta subunit of the receptor. The bound receptor is able to autophosphorylate and phosphorylate numerous intracellular substrates such as insulin receptor substrates (IRS) proteins, Cbl, APS, Shc and Gab 1. These activated proteins, in turn, lead to the activation of downstream signaling molecules including PI3 kinase and Akt. Akt regulates the activity of glucose transporter 4 (GLUT4) and protein kinase C (PKC) which play a critical role in metabolism.

biotransformation

Insulin is predominantly cleared by metabolic degradation via a receptor-mediated process.