A novel series of 4-piperidinopyridines and 4-piperidinopyrimidines showed potent and selective inhibition of rat 2, 3-oxidosqualene cyclase-lanosterol synthase (OSC)(eg 26 IC50 rat= 398±25 nM, human= 112±25 nM) and gave selective oral inhibition of rat cholesterol biosynthesis (26 ED80= 1.2±0.3 mg/kg, n= 5; HMGCoA reductase inhibitor simvastatin ED80= 1.2±0.3 mg/kg, n= 5). The piperidinopyrimidine OSC inhibitors have a significantly ...