Development and validation of a liquid chromatography-tandem mass spectrometry method for simultaneous determination of amlodipine, atorvastatin and its metabolites ortho-hydroxy atorvastatin and para-hydroxy atorvastatin in human plasma and its applicati

Chromatograms and retention times of AM, AT, o-AT, p-AT at LLOQ and IS, which indicated good specificity and selectivity of the established method with lower LLOQ. (A) Double blank human plasma; (B) blank plasma spiked with AM, AT, o-AT, p-AT (LLOQ) and IS (50 ng/mL); and (C) plasma sample obtained 1 h after administration of test drugs (AM/AT, 5 mg/10 mg).