Quantitative determination of erlotinib and O-desmethyl erlotinib in human EDTA plasma and lung tumor tissue

Background: To increase knowledge about lung tumor tissue levels of erlotinib and its primary active metabolite, and about erlotinib plasma levels in intercalated dosing schedules, a sensitive and accurate method for determination of erlotinib and O-desmethyl erlotinib (OSI-420) in human plasma and lung tumor tissue has been developed. Results: A method with HPLC-MS/MS was validated over a linear range from 5 to 2500 ng/ml in plasma and from 5.0 to 500 ng/ml for lung tumor tissue homogenate (50-5000 ng/g for lung tumor). Calibration curves in plasma were used to quantify analytes in lung tumor tissue homogenate. Lung tumor tissue of 15 patients has been collected and analyzed with the presented method. Conclusion: This method has been successfully validated and applied to determine plasma and lung tumor tissue concentrations of erlotinib and O-desmethyl erlotinib in patients with non-small-cell lung cancer.