Generic Name

Humalog

Mechanism

Humalog (insulin lispro) is a rapid‑acting insulin analog.
• *Structure*: Lispro replaces Pro^28 with Arg and Arg^29 with Pro, reducing hexamer formation and enabling rapid absorption.
• *Action*: It binds to the insulin receptor, mimicking endogenous insulin by activating the tyrosine‑kinase pathway and promoting glucose uptake in muscle and adipose tissue while inhibiting hepatic gluconeogenesis.
• *Clinical effect*: Peak activity occurs within 30–90 min, with a duration of 3–5 h, providing post‑prandial glycemic control without the lag of regular insulin.

Pharmacokinetics

• Onset: ~10–20 min after subcutaneous injection.
• Peak: 30–90 min (varies with site and exogenous factors).
• Duration: 3–5 h, ensuring rapid post‑meal glucose fall.
• Half‑life: ~90 min, markedly shorter than human insulin due to reduced hexamer formation.
• Metabolism: Catabolized by the liver and kidneys without the need for dosage adjustment in mild to moderate renal impairment.
• Storage: Store refrigerated (2–8 °C); at room temperature up to 28 days for unopened vials, 28 days after reconstitution, and 6 hrs at 37 °C after activation.

Indications

• Type 1 diabetes mellitus e.g., insulin‑dependent patients needing post‑prandial control.
• Type 2 diabetes mellitus in patients on basal‑bolus insulin regimens.
• Post‑operative adjustment of hyperglycemia in insulin‑dependent patients.
• Adjunctive therapy in patients using timing‑sensitive basal insulin or premixed formulations.

Contraindications

• Known hypersensitivity to insulin lispro, insulin, bovine collagen, or any excipient.
• Current hypoglycemia; treat to normal BG before addition of Humalog.
• Pregnancy & lactation: Use only if clearly indicated; it crosses placenta.
• Severe hepatic impairment: Potential for prolonged action; monitor glucose closely.
• Concurrent hypoglycemic agents: Increase risk of severe hypoglycemia.

Dosing

• Initial: 0.2–0.5 U/kg/day divided by meals for type 1; 0.1–0.3 U/kg/day for type 2 on basal‑bolus therapy.
• Adjustment: Titrate to individual fasting and pre‑meal glucose targets; increase post‑meal dose for hyperglycemia or reduce for hypoglycemia.
• Injection: 30–60 min before meals (or within 5 min pre‑meal). Rotate sites in abdomen, thigh, buttock, and upper arm.
• Mixing: Can be mixed with long‑acting NPH insulin at a 1:3 ratio for pens/MDI.
• Reconstitution: One prefilled pen or vial ×10 U/mL, ready for use without additional treatment.
• Duration: Day‑to‑day equivalence; no ovary‑depletion needed.

Adverse Effects

*Common*
• Hypoglycemia (most frequent, often around meals).
• Injection‑site reactions—pain, erythema, induration.
• Weight gain.
• Edema (rare).

*Serious*
• Severe hypoglycemia—risk of seizures, coma.
• Anaphylaxis (rare, often due to protein additives).
• Lipohypertrophy, reversible fatty infiltration.

Monitoring

• Self‑monitoring blood glucose (SMBG): Pre‑meal and 1–2 h post‑meal for first 2 weeks, then as per protocol.
• HbA1c: Every 3 months.
• Ketones: In low‑carb or high‑stress states to detect ketoacidosis.
• Weight: Check monthly to track insulin‑induced gain.
• Injection site inspection: Rotate sites; evaluate for lipomas or lipoatrophy.
• Blood pressure & lipids: Optional baseline, as insulin may influence.

Clinical Pearls

• Timing is critical: Inject Humalog 5 min before a meal or within 15 min after breakfast for optimal peak in post‑prandial glucose falls.
• Mixing with NPH: Use a 1:3 ratio; keep humidified pen; re‑inject after at most 2 hrs to avoid pre‑treatment of basal.
• Underweight patients: Start lower (0.1 U/kg/day) to minimize hypoglycemia.
• Travel & shift work: If you miss a dose, treat with glucagon or 15‑g carbohydrate, because rapid‑acting insulin has very short duration.
• Reconstitution check: Verify correct colour and clarity; turbid or faint may indicate expired product.
• Patient education: Emphasize the difference between Humalog and regular insulin—Humalog does not require the “30 min before meal” rule.
• Metformin synergy: Combine with metformin to modestly reduce insulin dose and weight gain risk.

*Humalog* remains the gold‑standard rapid‑acting insulin analog for daytime post‑prandial glucose control, offering patients and clinicians a predictable, short‑acting option with a clear dosing window and manageable side‑effect profile.