indication

For the treatment of type 1 or 2 diabetes mellitus. May be used in combination with oral anti-diabetic agents in type 2 diabetic patients who are not in adequate metabolic control with oral anti-diabetic agents alone.

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. Increased insulin secretion following meals is 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 detemir is a long-acting insulin analogue with a flat and predictable action profile. It is used to mimic the basal levels of insulin in diabetic individuals. The onset of action of insulin detemir is 1 to 2 hours and its duration of action is up to 24 hours.

mechanism of action

Insulin detemir 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. Insulin detemir’s long duration of action appears to be a result of slow systemic absorption from the injection site and delayed distribution to target tissues. The myristic acid side chain on insulin detemir increases self-association and gives it a high binding affinity to serum albumin. These features slows its distribution into target tissues and prolongs its duration of action.

toxicity

Hypoglycemia may occur with inappropriately high doses. 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. Injection site reactions may also occur. Symptoms include: redness, inflammation, bruising, swelling and itching at the injection site.

biotransformation

As with natural insulin, all metabolites formed are inactive.

absorption

Maximum serum concentrations are reached 6 to 8 hours following subcutaneous injection. Bioavailability is approximately 60%.

half life

5 - 7 hours depending on dose

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 detemir. Monitor for changes in fasting and postprandial blood sugars.