Simultaneous estimation of amlodipine and atenolol in human plasma: a sensitive LC-MS/MS method validation and its application to a clinical PK study.

Background: A highly sensitive, specific and rapid LC-ESI-MS/MS method has been developed and validated for simultaneous quantification of amlodipine (AMD) and atenolol (ATL) in human plasma (200 µl) using AMD-d4 and ATL-d7, respectively, as an internal standard (IS) as per the regulatory guidelines.

Results: The SPE method was used to extract the analytes and IS from human plasma. The chromatographic resolution of AMD, ATL and corresponding IS was achieved using an isocratic flow on a C18 column. The total chromatographic run time was 3 min. A linear response function was established for the range of concentrations 50-8000 pg/ml and 10-800 ng/ml for AMD and ATL, respectively, in human plasma.

Conclusion: The intra- and inter-day accuracy and precision values for AMD and ATL met the acceptance as per regulatory guidelines. The validated assay was applied to a fixed-dose combination of AMD and ATL (Adopin-AT(®)) PK study in humans.