About Insulin Isophane NPH Pancreatic hormone, Intermediate-acting insulin analogue, Antidiabetic Agent. Mechanism of Action of Insulin Isophane NPH It is an intermediate acting antihyperglycaemic drug. Insulin acts through binding to a subunit of insulin receptors located on the cell membrane of all cells (highest densities are seen in muscle, liver, and adipose tissue).This binding induces aggregation and internalization of the receptor along with the bound Insulin. This activates tyrosine kinase activity of the ? subunits and tyrosine residues of the ? subunits get autophosphorylated- thus the activity of this subunit to phosphorylate tyrosine residues of Insulin Receptor Substrate proteins (IRS1, IRS2) is increased. These results in a cascade of phosphorylation and dephosphorylation reactions which lead to stimulation or inhibition of enzymes involved in the metabolic actions of Insulin.