N-desmethyl Rosuvastatin is an active metabolite of the HMG-CoA reductase inhibitor rosuvastatin .1,2 N-desmethyl Rosuvastatin is formed when rosuvastatin undergoes demethylation, primarily by the cytochrome P450 (CYP) isoform CYP2C9 and to a lesser extent by CYP2C19 and CYP3A4.1
1.Macwan, J.S., Ionita, I.A., and Akhlaghi, F.A simple assay for the simultaneous determination of rosuvastatin acid, rosuvastatin-5S-lactone, and N-desmethyl rosuvastatin in human plasma using liquid chromatography-tandem mass spectrometry (LC-MS/MS)Anal. Bioanal. Chem.402(3)1217-1227(2012) 2.Bai, X., Wang, X.P., He, G.D., et al.Simultaneous determination of rosuvastatin, rosuvastatin-5 S-lactone, and N-desmethyl rosuvastatin in human plasma by UPLC-MS/MS and its application to clinical studyDrug Res. (Stuttg.)68(6)328-334(2018)