Simultaneous determination of olmesartan and amlodipine in human plasma and urine by ultra performance liquid chromatography tandem mass spectrometry

A sensitive and rapid ultra performance liquid chromatography tandem mass spectrometry (UPLC–MS/MS) method was developed to determine olmesartan and amlodipine levels in human plasma and urine simultaneously. Chromatographic separation was carried out on an Acquity UPLC BEH C18 column and mass spectrometric analysis was performed using a QTrap5500 mass spectrometer coupled with an electro-spray ionization (ESI) source in the positive ion mode. The MRM transitions of m/z 447 → 207 and 409 → 238 were used to quantify olmesartan and amlodipine, respectively. This assay method has been fully validated in terms of selectivity, linearity, lower limit of quantification (LLOQ), accuracy, precision, stability, matrix effect and recovery. The linearity of this method was found to be within the concentration range of 0.2–500 ng/mL and 4–5000 ng/mL for olmesartan in human plasma and urine and 0.1–50 ng/mL and 2–1000 ng/mL for amlodipine in human plasma and urine. Only 2 min were needed for an analytical run. This assay was used to support a clinical study where multiple oral doses were administered to healthy Chinese subjects to investigate the pharmacokinetics of olmesartan and amlodipine