 In addition to these interactions atorvastatin and rosuvastatin also form unique hydrogen bonds between Ser565 residue and either a carbonyl oxygen atom (atorvastatin) or a sulfone oxygen atom (rosuvastatin).A unique polar interaction between the Arg568 side chain and the electronegative sulfone group on rosuvastatin makes it the statin that has the greatest number of bonding interactions with HGMR.All statins have the same pharmacophore so the difference in their pharmacodynamic effect is mostly based on the substituents.