Pactimibe (CS-505 free base) is a dual?ACAT1/2?inhibitor with?IC50s of 4.9 μM and 3.0 μM, respectively. Pactimibe (CS-505 free base) inhibits?ACAT?with?IC50s of 2.0 μM, 2.7 μM, 4.7 μM in the liver, macrophages and THP-1 cells, respectively[1]. Pactimibe (CS-505 free base) noncompetitively inhibits?oleoyl-CoA?with a?Ki?value of 5.6 μM. Moreover, Pactimibe (CS-505 free base) obviously inhibits?cholesteryl ester formation?with an?IC50?of 6.7 μM. Pactimibe (CS-505 free base) possesses anti-atherosclerotic potential with lowering plasma cholesterol activity