Biochemical and physiological properties of a novel series of long-acting insulin analogs obtained by acylation with cholic acid derivatives

This study was conducted to assess the suitability of insulin analogs acylated by various cholic acid derivatives for use as basal insulin, and to test the most promising of these, LysB29(Nepsilon-lithocholyl-gamma-Glu) des(B30) human insulin (NN344) in pigs. Circular dichroism spectroscopy and size-exclusion chromatography were used to explore the physicochemical properties of the analogs, and affinities for albumin and insulin receptors were determined. After subcutaneous injection in pigs, disappearance half-times were measured, and the plasma profile and glucose-lowering effect in a euglycemic clamp were assessed for NN344. NN344 showed glucose-lowering activity lasting more than 24 h. Glucose infusion rate was essentially constant from 5 to 19 h after injection. NN344 seemed to be a dodecamer in the presence of zinc ions and phenol. Without phenol, the apparent molecular mass was >5000 kDa. Formation of such a self-assembly at the site of s.c. injection and its subsequent slow decomposition might explain the long duration of action of NN344. A measurable affinity for albumin of the lithocholic acid ligand may also contribute to the prolonged action. NN344 is a candidate for a neutral soluble basal insulin that might offer people with diabetes a prolonged duration, smooth, and predictable basal insulin supplement.