Direct comparison of radioimmunoassay and LC–MS/MS for PK assessment of insulin glargine in clinical development

Background: A direct comparison of radioimmunoassay (RIA) and LC–MS/MS for insulin glargine quantification in human plasma is provided. Results: Compared with the RIA, the LC–MS/MS assay exhibited comparable/improved sensitivity (LLOQ at 0.1 ng/ml [˜16.7 pM or 2.8 μU/ml] for glargine and its metabolites M1 and M2, respectively) and ruggedness. Most importantly, it demonstrated a superior specificity advantage against the interference from endogenous insulin, exogenous insulin analogs (e.g., Novolog®, Humalog® or Levemir®, routine treatment for diabetes mellitus) and potentially pre-existing anti-insulin antibodies in patient samples. The data obtained from diabetic patients suggested the LC–MS/MS assay substantially improved pharmacokinetic characterization of glargine....