High-performance liquid chromatography with ultraviolet detection for therapeutic drug monitoring of everolimus

We developed and validated a high-performance liquid chromatography-ultraviolet (HPLC-UV) method for determining everolimus concentrations in human whole blood. Sample preparation involved a solid-phase extraction after protein precipitation. The separation of everolimus from internal standard (IS) and endogenous components was achieved using an isocratic elution on an octyl column. The method showed a linear relationship between peak height ratios and blood concentrations in the range of 1-200 ng/mL (r2 = 0.9997). The observed intra- and inter-day assay imprecision had a coefficient of variation (CV) = 12.8%, and inaccuracy was 11.4%. The method was found to be precise, accurate, and sensible making it useful for routine therapeutic monitoring of everolimus.