The accurate determination of pharmacokinetic properties of biologic molecules is one important part in the development process of biotherapeutic drugs. Currently, enzyme-linked immunoassays (ELISA) are the gold-standard to measure the concentration of therapeutic antibodies and protein biomarkers but they require lengthy development of custom antibodies and can be prone to severe matrix effects, resulting in inaccurate measurements.
As an attractive alternative, liquid chromatography (LC) in combination with quantitative mass spectrometry (MS) and sophisticated sample enrichment workflows is now available for the bioanalysis of therapeutic proteins. LC-MS workflows offer superior specificity and sensitivity and interferences from complex sample matrices are basically eliminated.
A simple, rapid, and sensitive method for the determination of raloxifene (RAL) and its two active metabolites, raloxifene-4-glucuronide (R4G) and raloxifene-6-glucuronide (R6G), in human plasma by liquid chromatographytandem mass spectrometry using raloxifene-d4 as an internal standard was developed and evaluated.