Quantitative determination of atorvastatin and para-hydroxy atorvastatin in human plasma by LC-MS-MS.

A specific, sensitive, and fast method based on high-performance liquid chromatography coupled to tandem mass spectrometry was developed for the determination of atorvastatin and para-hydroxy atorvastatin in human plasma. Solid-phase extraction was used to isolate the compounds from human plasma followed by injection of the extracts onto a C18 column with isocratic elution. The lower limits of quantitation was 0.229 and 0.202 ng/mL for atorvastatin and para-hydroxy atorvastatin in human plasma, respectively. The method was then successfully applied to the pharmacokinetic study of atorvastatin in healthy Chinese male subjects.