indication

For the treatment of Type 1 and 2 diabetes mellitus. Should be used in regimens including a long-acting or basal insulin analogue unless it is used in a continuous infusion pump. May be used with oral antidiabetic agents.

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 glulisine is a rapid-acting insulin analogue used to mimic postprandial insulin spikes in diabetic individuals. The onset of action of insulin glulisine is approximately 15 minutes. Its activity peaks 60 minutes following subcutaneous injection and its duration of action is 2-4 hours.

mechanism of action

Insulin glulisine 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 arginine at position B3 for lysine and replacement of the B29 lysine with glutamic acid decreases the propensity to form hexamers, stabilizes the hormone in monomeric form and results in a rapid rate of absorption and short 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

Absolute bioavailability following subcutaneous administration is approximately 70%. Time to maximum plasma concentration is approximately 60 minutes.

half life

42 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 glulisine. Monitor for changes in fasting and postprandial blood sugars.