Coenzyme Q10 be measured in blood plasma, these measurements reflect dietary intake rather than tissue status. Currently, most clinical centers measure CoQ levels in cultured skin fibroblasts, muscle biopsies, and blood mononuclear cells. Culture fibroblasts can be used also to evaluate the rate of endogenous CoQ biosynthesis, by measuring the uptake of C-labelled "p"-hydroxybenzoate. CoQ shares a biosynthetic pathway with cholesterol. The synthesis of an intermediary precursor of CoQ, mevalonate, is inhibited by some beta blockers, blood pressure-lowering medication, and statins, a class of cholesterol-lowering drugs. Statins can reduce serum levels of CoQ by up to 40%. CoQ is not approved by
Lovastatin the β-hydroxy acid open ring form; which is the active form. Lovastatin and other statins have been studied for their chemopreventive and chemotherapeutic effects. No such effects were seen in the early studies. More recent investigations revealed some chemopreventive and therapeutic effects, for certain types of cancer, especially in combination of statins with other anticancer drugs. It is likely that these effect are mediated by the properties of statins to reduce proteasome activity, leading to an accumulation of cyclin-dependent kinase inhibitors p21 and p27, and to subsequent G-phase arrest, as seen in cells of different cancer lines. Compactin and lovastatin,