1. Clinical Overview
Insulin Lispro is a rapid-acting human insulin analogue used for the control of hyperglycemia in diabetes mellitus. It is created by reversing the amino acids proline and lysine at positions 28 and 29 on the insulin B-chain. This modification reduces the molecule's tendency to self-associate into dimers and hexamers, allowing for faster absorption from subcutaneous tissue, a more rapid onset of action, and a shorter duration of effect compared to regular human insulin. It is typically administered immediately before or after meals to control postprandial glucose spikes.
| Onset | Duration | Bioavailability |
|---|---|---|
| Approximately 15 minutes after subcutaneous injection. | Approximately 2 to 5 hours. | 55-77% after subcutaneous administration. |
2. Mechanism of Action
Insulin Lispro binds to the alpha-subunit of the transmembrane insulin receptor, which is a tyrosine kinase. This binding triggers autophosphorylation of the receptor and subsequent phosphorylation of intracellular signaling proteins (IRS-1, Shc). This cascade activates downstream pathways (PI3-kinase/Akt and MAPK), leading to the translocation of glucose transporter type 4 (GLUT4) to the cell membrane, facilitating cellular uptake of glucose. It also promotes glycogen, fatty acid, and protein synthesis while inhibiting gluconeogenesis, glycogenolysis, lipolysis, and proteolysis.
3. Indications & Uses
- Treatment of Type 1 Diabetes Mellitus.
- Treatment of Type 2 Diabetes Mellitus where glycemic control is not achieved with oral hypoglycemic agents, diet, and exercise.
4. Dosage & Administration
Adult Dosage: Highly individualized. Typically 0.5 to 1.0 unit/kg/day, divided into pre-meal (bolus) doses. The pre-meal dose is based on carbohydrate intake, pre-meal blood glucose, and anticipated physical activity. Usually administered 0-15 minutes before or immediately after a meal.
Administration: For subcutaneous injection only. Use in the abdominal wall, thigh, upper arm, or buttocks. Rotate injection sites within the same region. Inject into the subcutaneous tissue, not intramuscularly. Use appropriate insulin syringes, pens, or pumps. Do not mix with other insulins in the same syringe unless specifically indicated (e.g., with specific premixed formulations). Visually inspect before use.
5. Side Effects
Common side effects may include:
- Hypoglycemia (most common)
- Injection site reactions (pain, redness, itching, swelling)
- Lipodystrophy (lipohypertrophy or lipoatrophy at injection site)
- Weight gain
- Peripheral edema (especially upon initiation).
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Corticosteroids (e.g., Prednisolone) | Antagonize insulin effect, leading to hyperglycemia and increased insulin requirement. | Major |
| Beta-blockers (e.g., Propranolol) | May mask tachycardia as a sign of hypoglycemia and impair counter-regulatory response. Can also potentiate hypoglycemia. | Major |
| Thiazide Diuretics (e.g., Hydrochlorothiazide) | May cause hyperglycemia, increasing insulin requirement. | Moderate |
| Alcohol | Potentiates hypoglycemic effect and can impair gluconeogenesis, increasing risk of severe hypoglycemia. | Major |
| MAO Inhibitors, ACE Inhibitors | May potentiate hypoglycemic effect. | Moderate |
| Oral Hypoglycemic Agents (e.g., Sulfonylureas) | Additive hypoglycemic effect, increasing risk of hypoglycemia. | Major |
| Octreotide, Lanreotide | Alters glucose metabolism; may increase or decrease insulin requirement. | Moderate |
| Atypical Antipsychotics (e.g., Olanzapine) | May cause hyperglycemia, increasing insulin requirement. | Moderate |
7. Patient Counselling
- DO inject 0-15 minutes before or immediately after a meal as directed.
- DO rotate injection sites within the same body area to prevent lipodystrophy.
- DO regularly monitor blood glucose levels, especially before meals and at bedtime.
- DO carry a fast-acting sugar source (glucose tablets) at all times.
- DO inform all healthcare providers you are on insulin.
- DON'T skip meals after taking insulin.
- DON'T inject into muscle, scars, or areas of lipodystrophy.
- DON'T share insulin pens or syringes.
- DON'T use if the solution is cloudy, discolored, or contains particles.
8. Toxicology & Storage
Overdose: Symptoms are those of profound hypoglycemia: sweating, tremor, tachycardia, palpitations, hunger, anxiety, confusion, drowsiness, slurred speech, headache, seizures, coma, and death.
Storage: Unopened vials/pens: Store in a refrigerator at 2°C to 8°C. Do not freeze. Keep away from the cooling element. Opened (in-use) vial: Can be kept at room temperature (below 30°C) or refrigerated. Use within 28 days. Opened (in-use) insulin pen: Store at room temperature (below 30°C). Do not refrigerate. Use within 28 days. Protect from direct heat and light. Do not use if frozen or exposed to excessive heat. For Indian climatic conditions, if reliable refrigeration is unavailable, a cool pouch can be used for transport.