Elucidating the Mechanism of Absorption of Fast-Acting Insulin Aspart: The Role of Niacinamide

Pharm Res. 2019 Feb 11;36(3):49. doi: 10.1007/s11095-019-2578-7.


Purpose: Fast-acting insulin aspart (faster aspart) is a novel formulation of insulin aspart containing two additional excipients: niacinamide, to increase early absorption, and L-arginine, to optimize stability. The aim of this study was to evaluate the impact of niacinamide on insulin aspart absorption and to investigate the mechanism of action underlying the accelerated absorption.

Methods: The impact of niacinamide was assessed in pharmacokinetic analyses in pigs and humans, small angle X-ray scattering experiments, trans-endothelial transport assays, vascular tension measurements, and subcutaneous blood flow imaging.

Results: Niacinamide increased the rate of early insulin aspart absorption in pigs, and pharmacokinetic modelling revealed this effect to be most pronounced up to ~30-40 min after injection in humans. Niacinamide increased the relative monomer fraction of insulin aspart by ~35%, and the apparent permeability of insulin aspart across an endothelial cell barrier by ~27%. Niacinamide also induced a concentration-dependent vasorelaxation of porcine arteries, and increased skin perfusion in pigs.

Conclusion: Niacinamide mediates the acceleration of initial insulin aspart absorption, and the mechanism of action appears to be multifaceted. Niacinamide increases the initial abundance of insulin aspart monomers and transport of insulin aspart after subcutaneous administration, and also mediates a transient, local vasodilatory effect.

Keywords: absorption; fast-acting insulin aspart; niacinamide; oligomerization; vasodilation.

Publication types

  • Video-Audio Media

MeSH terms

  • Animals
  • Cells, Cultured
  • Diabetes Mellitus, Type 1 / blood
  • Diabetes Mellitus, Type 1 / drug therapy*
  • Dose-Response Relationship, Drug
  • Endothelial Cells / metabolism
  • Female
  • Humans
  • Hypoglycemic Agents / administration & dosage
  • Hypoglycemic Agents / pharmacokinetics*
  • Injections, Subcutaneous
  • Insulin Aspart / administration & dosage
  • Insulin Aspart / pharmacokinetics*
  • Models, Biological
  • Niacinamide / pharmacology*
  • Regional Blood Flow / drug effects
  • Scattering, Small Angle
  • Subcutaneous Absorption / drug effects*
  • Subcutaneous Tissue / blood supply
  • Subcutaneous Tissue / drug effects
  • Subcutaneous Tissue / metabolism
  • Sus scrofa
  • Vasodilation / drug effects
  • X-Ray Diffraction


  • Hypoglycemic Agents
  • Niacinamide
  • Insulin Aspart

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