Analytical validation of a quantitative method for therapeutic drug monitoring on the Alinity®c Abbott

Objective: The aim of this study was to evaluate the analytical
performance of the Alinity®c Abbott compared to the Architect® immunoassay system for the determination of drugs having a narrow therapeutic index.
Methods: Valproic acid, amikacin, gentamicin, phenobarbital and vancomycin
were analyzed using Particle-Enhanced Turbidimetric Inhibitor Immunoassay
(Petinia), phenytoin and theophylline were analyzed using an immunoenzymatic method and a colorimetric method was performed to quantify lithium.
The methods were validated according to the total error approach. Seven validation standards were analyzed in quintuplet during four days to establish
the limits of the methods. Dilution integrity and interferences (hemolysis and
high concentrations of bilirubin and lipids) were also tested. Depending on
the analyte, the results obtained for twenty to forty patients on the Alinity®
were compared to those obtained on the Architect®. Results: The bias and the
coefficients of variation for repeatability and for intermediate precision were
lower than 15% for all drugs. Accuracy profiles were acceptable (acceptance
limits fixed at 30%) in the validated ranges. The lower limits of quantification
(LLOQ) were similar to those determined by Abbott except for gentamicin for
which we determined a LLOQ at 1.22 mg/L while Abbott determined it at 0.5
mg/L. All assays diluted linear and analyte concentrations were not affected
by interferences. Concentrations obtained for real samples on the Alinity®c are
comparable to those obtained on the Architect®ci. Conclusions: The analytical
validation of a method suitable for therapeutic drug monitoring of drugs on the
Alinity®c meets the requirements of European Medicines Agency