CAS 163217-70-7: (2R-trans)-5-(4-Fluorophenyl)-2-(1-methylethyl)-N-(4-hydroxyphenyl)-4-phenyl-1-[2-(tetrahydro-4-hydroxy-6-oxo-2H-pyran-2-yl)-ethyl]-1H-pyrrole-3-carboxamide

4-Hydroxy atorvastatin lactone is a prodrug that can be hydrolyzed to the active form, atorvastatin. It is an inhibitor of HMG-CoA reductase and has been shown to significantly lower cholesterol levels in humans. 4-Hydroxy atorvastatin lactone has been shown to have no significant drug interactions with other drugs metabolized by cytochrome P450 3A5 (CYP3A5). A pharmacokinetic study of healthy Chinese subjects showed that plasma concentrations of 4-hydroxy atorvastatin lactone increased with increasing doses. Linear ranges were observed for human liver validation studies. Pharmacokinetic parameters were determined using chromatographic science, including linearity, limit of detection, limit of quantification, and specificity. The validation study was completed using electrospray ionization mass spectrometry.