indication

For the treatment of Type 1 or 2 diabetes mellitus. Should normally be used in conjunction with an intermediate or long-acting insulin.

pharmacology

Insulin is a natural hormone produced by beta cells of the pancreas. In non-diabetic individuals, a basal level of insulin is supplemented with insulin spikes following meals. Postprandial insulin spikes are responsible for the metabolic changes that occur as the body transitions from a postabsorptive to absorptive state. Insulin promotes cellular uptake of glucose, particularly in muscle and adipose tissues, promotes energy storage via glycogenesis, opposes catabolism of energy stores, increases DNA replication and protein synthesis by stimulating amino acid uptake by liver, muscle and adipose tissue, and modifies the activity of numerous enzymes involved in glycogen synthesis and glycolysis. Insulin also promotes growth and is required for the actions of growth hormone (e.g. protein synthesis, cell division, DNA synthesis). Insulin aspart is a rapid-acting insulin analogue used to mimic postprandial insulin spikes in diabetic individuals. The onset of action of insulin aspart is 10-15 minutes. Its activity peaks 60-90 minutes following subcutaneous injection and its duration of action is 4-5 hours.

mechanism of action

Insulin aspart 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 autophosphorylates and phosphorylates numerous intracellular substrates such as insulin receptor substrates (IRS) proteins, Cbl, APS, Shc and Gab 1. Activation of these proteins leads 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), both of which play critical roles in metabolism and catabolism. In humans, insulin is stored in the form of hexamers; however, only insulin monomers are able to interact with IR. Substitution of the proline residue at B28 with aspartic acid reduces the tendency to form hexamers and results in a faster rate of absorption and onset of action and shorter duration of action.

toxicity

Inappropriately high dosages relative to food intake and/or energy expenditure may result in severe and sometimes prolonged and life-threatening hypoglycemia. Neurogenic (autonomic) signs and symptoms of hypoglycemia include trembling, palpitations, sweating, anxiety, hunger, nausea and tingling. Neuroglycopenic signs and symptoms of hypoglycemia include difficulty concentrating, lethargy/weakness, confusion, drowsiness, vision changes, difficulty speaking, headache, and dizziness. Mild hypoglycemia is characterized by the presence of autonomic symptoms. Moderate hypoglycemia is characterized by the presence of autonomic and neuroglycopenic symptoms. Individuals may become unconscious in severe cases of hypoglycemia.

absorption

Rapidly absorbed following subcutaneous administration.

half life

81 minutes

drug interactions

Acebutolol: The beta-blocker, acebutolol, may decrease symptoms of hypoglycemia.

Atenolol: The beta-blocker, atenolol, may decrease symptoms of hypoglycemia.

Bisoprolol: The beta-blocker, bisoprolol, may decrease symptoms of hypoglycemia.

Carvedilol: The beta-blocker, carvedilol, may decrease symptoms of hypoglycemia.

Clofibrate: Increases the effect of insulin

Dexfenfluramine: Fenfluramine increases the effect of insulin

Esmolol: The beta-blocker, esmolol, may decrease symptoms of hypoglycemia.

Fenfluramine: Fenfluramine increases the effect of insulin

Somatropin recombinant: Somatropin may antagonize the hypoglycemic effect of insulin aspart. Monitor for changes in fasting and postprandial blood sugars.