4-hydroxy Atorvastatin lactone

4-hydroxy Atorvastatin lactone is a metabolite of atorvastatin (Item No. 10493), an HMG-CoA reductase inhibitor present in formulations that have been used to treat hypercholesterolemia and certain dyslipidemias.{18239,18240,18241,18235} Atorvastatin is metabolized by the cytochrome P450 (CYP) isoform CYP3A4 to form 4-hydroxy atorvastatin (Item No. 22575) and 2-hydroxy atorvastatin, which can be interconverted between their acid and lactone forms.{18239} Atorvastatin can itself be lactonized to atorvastatin lactone (Item No. 20951) then metabolized by CYP3A4 directly to 4-hydroxy atorvastatin lactone and 2-hydroxy atorvastatin lactone.