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

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.

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^®.

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.

The analytical validation of a method suitable for therapeutic drug monitoring of drugs on the Alinity^®c meets the requirements of European Medicines Agency.