1. Clinical Overview
Insulin Glargine 300 units/mL (U-300) is a long-acting, concentrated basal insulin analogue. It is a biosimilar to the originator product, designed to provide a more stable and prolonged pharmacokinetic/pharmacodynamic profile compared to Insulin Glargine 100 units/mL (U-100). It provides a flatter and more extended blood glucose-lowering effect with a duration of action beyond 24 hours, allowing for once-daily subcutaneous administration. It is indicated for the treatment of diabetes mellitus in adults and children.
| Onset | Duration | Bioavailability |
|---|---|---|
| Approximately 6 hours | Up to 36 hours (mean duration ~24-30 hours) | Approximately 60-70% following subcutaneous administration |
2. Mechanism of Action
Insulin Glargine is a recombinant human insulin analogue where asparagine at position A21 is replaced by glycine and two arginines are added to the C-terminus of the B-chain. This modification shifts the isoelectric point towards a neutral pH, making it less soluble at physiological pH. Upon subcutaneous injection, it forms microprecipitates from which small amounts of insulin glargine are slowly released, resulting in a prolonged, peakless profile.
3. Indications & Uses
- Treatment of type 1 diabetes mellitus in adults and children (≥2 years)
- Treatment of type 2 diabetes mellitus in adults
4. Dosage & Administration
Adult Dosage: Individualized. Typically initiated at 0.2 units/kg or 10 units once daily, adjusted based on glycemic response. When switching from other basal insulins, a dose reduction of ~10-20% may be required initially to minimize hypoglycemia risk.
Administration: For subcutaneous injection only. Administer once daily at the same time each day, preferably in the evening. Rotate injection sites (abdomen, thigh, or upper arm) to prevent lipodystrophy. Use a U-100 insulin syringe calibrated for U-300 insulin or a dedicated pen device. Do NOT administer intravenously or intramuscularly. Do NOT mix with other insulins.
5. Side Effects
Common side effects may include:
- Hypoglycemia
- Injection site reactions (pain, redness, itching)
- Lipodystrophy (atrophy or hypertrophy at injection site)
- Peripheral edema
- Weight gain
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Oral Hypoglycemic Agents (e.g., Sulfonylureas, Meglitinides) | Additive hypoglycemic effect, increased risk of hypoglycemia | Major |
| Corticosteroids (e.g., Prednisolone, Dexamethasone) | Antagonize insulin effect, leading to hyperglycemia; dose increase may be needed | Major |
| Beta-blockers (e.g., Propranolol) | May mask tachycardia during hypoglycemia and impair counter-regulatory response | Moderate |
| Thiazide Diuretics | May cause hyperglycemia, reducing insulin efficacy | Moderate |
| ACE Inhibitors (e.g., Ramipril) | May enhance insulin sensitivity, increasing hypoglycemia risk | Moderate |
| Alcohol | Potentiates hypoglycemic effect and impairs gluconeogenesis; risk of delayed hypoglycemia | Major |
| Octreotide, Lanreotide | Alters glucose metabolism; may increase or decrease insulin requirement | Moderate |
7. Patient Counselling
- DO inject subcutaneously, rotating sites daily.
- DO use the correct syringe (U-100 syringe for U-300 insulin) or the dedicated pre-filled pen.
- DO monitor blood glucose regularly, especially when initiating or changing dose.
- DO carry a fast-acting sugar source (glucose tablets) at all times.
- DON'T mix Insulin Glargine 300 with any other insulin or diluent.
- DON'T share pens or syringes.
- DON'T skip meals after injection.
8. Toxicology & Storage
Overdose: Profound hypoglycemia: sweating, tremor, tachycardia, hunger, confusion, drowsiness, speech disturbance, seizures, coma, and potentially death.
Storage: Unopened (Refrigerated): Store at 2°C to 8°C. Do not freeze. Keep away from direct heat and light. In-use (Opened): May be stored at room temperature (below 30°C) for up to 28 days. Do not refrigerate the pen in use. Protect from excessive heat and sunlight. Do not use if the solution appears cloudy, discolored, or contains particles. Discard needle after each use.