Lovastatin-d9 is intended for use as an internal standard for the quantification of lovastatin (Item No. 10010338) by GC- or LC-MS. Lovastatin is an HMG-CoA reductase inhibitor that was originally isolated from A. terreus.1 It is a prodrug of its more potent metabolite, lovastatin hydroxy acid (Item No. 10010339). Both competitively inhibit HMG-CoA reductase with Ki values of 1.4 and 0.6 nM for lovastatin and the open ring, hydroxy acid form, respectively.2 Lovastatin (8 mg/kg per day) reduces plasma cholesterol in dogs by 29% over a three-week period. It also suppresses TNF-induced NF-κB activation (IC50 = ~15 µM), which potentiates apoptosis in human myeloid leukemia cells.3 Formulations containing lovastatin were the first HMG-CoA reductase inhibitors to be used in the treatment of hypercholesterolemia.WARNING This product is not for human or veterinary use.