(βR,δR,1S,2S,6R,8S,8aR)-8-[2,2-(Dimethyl-d6)-1-oxobutoxy]-1,2,6,7,8,8a-hexahydro-β,δ-dihydroxy-2,6-dimethyl-1-naphthaleneheptanoic Acid Ammonium Salt; Simvastatin-d6 Acid Ammonium Salt; Simvastatin-d6 Ammonium Salt; Simvastatin-d6 Carboxylic Acid Ammonium Salt