Novolog and Insulin Lispro: Different Rapid-Acting Insulin Analogs
No, Novolog (insulin aspart) and insulin lispro (Humalog) are not the same insulin product, though they are both rapid-acting insulin analogs with very similar pharmacokinetic and pharmacodynamic profiles.
Differences Between Insulin Aspart and Insulin Lispro
Insulin aspart (Novolog) and insulin lispro (Humalog) are distinct rapid-acting insulin analogs that differ in their molecular structure:
Molecular structure: Each has different amino acid modifications to the insulin molecule 1
- Insulin aspart: Proline at position B28 is replaced with aspartic acid
- Insulin lispro: Proline at position B28 and lysine at position B29 are reversed
Manufacturer:
- Insulin aspart (Novolog): Manufactured by Novo Nordisk
- Insulin lispro (Humalog): Manufactured by Eli Lilly
Similarities in Clinical Properties
Despite their structural differences, these insulins share remarkably similar clinical properties:
- Onset of action: Both have onset within 15-30 minutes 2
- Peak action: Both peak at approximately 1-3 hours 2
- Duration of action: Both last approximately 3-5 hours 2
- Timing of administration: Both should be administered immediately before meals 2
Comparative Efficacy and Clinical Use
Research has shown that insulin aspart and insulin lispro have virtually indistinguishable clinical effects:
A direct comparison study found that both insulins produced similar serum insulin levels (250-300 pmol/l) at approximately 30 minutes and disappeared from serum after approximately 4 hours 3
Both insulins had equivalent effects on:
- Glucose uptake
- Glucose oxidation
- Endogenous glucose production
- Lipid metabolism 3
Some studies suggest minor differences in absorption rates, with one study indicating insulin aspart may have slightly faster absorption compared to insulin lispro 4, though this has not translated to meaningful clinical differences 5
Clinical Applications
Both insulin aspart and insulin lispro are used in similar clinical scenarios:
- Basal-bolus regimens: Both are used as the bolus (mealtime) component 2
- Insulin pump therapy: Both are suitable for continuous subcutaneous insulin infusion (CSII) 2
- Dosing: Initial dosing recommendations are similar (0.1-0.2 units/kg per meal or 4 units per meal) 2
Important Clinical Considerations
Interchangeability: While pharmacologically similar, these insulins are not identical products and should not be automatically substituted without provider awareness
Prescription specificity: Prescriptions should specify which rapid-acting analog is intended
Patient education: Patients should be taught to recognize their specific insulin by both brand and generic name to avoid medication errors
Insurance considerations: Insurance formularies may cover one product but not the other, potentially affecting patient access and costs 2
Conclusion
While insulin aspart (Novolog) and insulin lispro (Humalog) are different insulin products with distinct molecular structures, their clinical profiles are remarkably similar. For most patients, the choice between these two rapid-acting insulin analogs would have minimal impact on glycemic control outcomes.