Singapore Drugs Database

Indication

For the treatment of Type 1 or 2 diabetes mellitus in patients over 17 years old who require a long-acting (basal) insulin for the control of hyperglycemia. May be used in pediatric patients with Type 1 diabetes mellitus who require a long-acting (basal) insulin for glycemic control.

Mechanism of Action

Insulin glargine 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. Insulin glargine is completely soluble at pH 4, the pH of administered solution, and has low solubility at physiological pH 7.4. Upon subcuteous injection, the solution is neutralized resulting in the formation of microprecipitates. Small amounts of insulin glargine are released from microprecipitates giving the drug a relatively constant concentration over time profile over 24 hours with no pronounced peak. This release mechanism allows the drug to mimic basal insulin levels within the body.

Pharmacokinetics

Absorption

Because of the modifications to the A and B chain, the isoelectric point shifts towards a neutral pH and insulin glargine is more stable in acidic conditions than regular insulin. As insulin glargine is less soluble at neutral pH, once injected, forms microprecipitates. Slow release of insulin glargine from microprecipitates provides a relatively constant concentration of insulin over 24 hours. Onset of action is approximately 1.1 hours.

Distribution

Metabolism

Partly metabolized to two active metabolites with similar in vitro activity to insulin: A21-Gly-insulin and A21-Gly-des-B30-Thr-insulin.

Elimination

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. Other adverse events that may occur include allergic reaction, injection site reaction, lipodystrophy, pruritis, and rash.

Active Ingredient/Synonyms

Insulin Glargine (rDNA origin) | Insulin glargine recombinant | Insulin Glargine |