Quality control and aggregation follow-up of insulin formulations

The prevalence of diabetes is increasing every year making insulin formulations widely prescribed medicines. Fast and efficient methods to assess the quality of such biopharmaceutical products are thus required, more particularly methods to assess the content of API and potential aggregates.
We started our study on insulin aggregation using the European Pharmacopeia method. Since methods to assess aggregate content are often contradictory, we also developed original and orthogonal methods using size-exclusion chromatography (SEC) and capillary gel electrophoresis (CGE). It was demonstrated that methods under neutral conditions (SEC and CGE) yield to similar aggregate content contrary to pharmacopeia SEC method that works under acidic conditions. Ion-mobility Q-TOF mass spectrometer was also used to confirm the presence and the identity of insulin dimers. Then, we applied the three methods to the analysis of an insulin formulation and similar results to those obtained for human insulin as raw material were observed. We also used the CGE method to study the stability of human insulin under different storage conditions.
Finally, we used UHPLC and mass spectrometry to quantify insulin formulation from different supply chains. We demonstrated that all the analyzed formulations had a potency between 95.0 % and 105.0 % of the potency stated on the label. This was useful to dispel doubts regarding issues in insulin cold chain supply recently described in the litterature.