Liquid Chromatography–Mass Spectrometry Method for the Estimation of Tacrolimus From Whole Blood Using Novel Time Programming Coupled With Diverter Valve Plumbing to Overcome the Matrix Effect

Tacrolimus is an immunosuppressant commonly used for the prevention of allograft rejection in transplant patients. Liquid chromatography mass spectrometry (LC-MS/MS) method was successfully developed and validated for the estimation of tacrolimus from whole blood. The extraction of the drug was achieved with protein precipitation followed by solid phase extraction. Tacrolimus related compound A was used as an internal standard. Electrospray ionization in negative mode and multiple reaction monitoring were used to monitor the ion transitions. The method was validated for the linear range of 0.200 ng/mL to 50.000 ng/mL with a correlation coefficient > 0.99. The matrix effect due to whole blood matrix was resolved using an optimized time programming coupled with diverter valve (Valco-valve) plumbing. The developed method was used to estimate tacrolimus concentrations from whole blood in a bioequivalence study. The clinical sample analysis was completed without any failure, and the study was found to be bioequivalent.