An enzyme-linked immunosorbent assay with a new way to control the edge effect and its application for bevacizumab pharmacokinetic studies in beagle dogs by fitting with a new pharmacokinetic model

Abstract

The edge effect in enzyme-linked immunosorbent assay (ELISA) affects bevacizumab plasma concentration detection with a higher absorbance of the wells at the edges of plates. Moreover, an inappropriate model fitting with classic compartment models also makes it hard to perform accurate pharmacokinetic (PK) studies for bevacizumab. In this work, an ELISA using a new method to control the edge effect was established for an accurate detection of bevacizumab plasma concentration. Accordingly, this new assay was applied to bevacizumab PK studies in beagle dogs combined with a new PK model based on bevacizumab complex elimination. This assay was proved to be accurate and reproducible when bevacizumab concentrations were between 25 and 800 pg mL⁻¹ with inaccuracy and imprecision below 15%. Moreover, the accuracy of the assay with control of the edge effect was significantly improved from the range of 98.61–134.01% to 104.81–105.89%, and the precision (relative standard deviation) was also improved from 13.10–37.90% to 3.60–5.45%. In the PK studies, bevacizumab nonlinear PK profiles were reasonably described with the new model based on bevacizumab complex elimination, and its fitting capacity was significantly improved compared to that of classic compartment models when the weighted residual sum of square of model fitting dramatically decreased. In conclusion, this new ELISA can control the influence of the edge effect, and it can play a major role in the PK studies of bevacizumab with the combined use of the new PK model.