(αS)-N-[(1S,3S,4S)-4-[[(2,6-DiMethylphenoxy)acetyl]aMino]-3-hydroxy-5-phenyl-1-(phenylMethyl)pentyl]tetrahydro-4-hydroxy-α-(1-Methylethyl)-2-oxo-1(2H)-pyriMidine-acetaMide Lopinavir Metabolite M3-M4 (Mixture of Diastereomers) Lopinavir Metabolite Lopinavir Impurity 23 1(2H)-Pyrimidineacetamide, N-[(1S,3S,4S)-4-[[2-(2,6-dimethylphenoxy)acetyl]amino]-3-hydroxy-5-phenyl-1-(phenylmethyl)pentyl]tetrahydro-4-hydroxy-α-(1-methylethyl)-2-oxo-, (αS)- Lopinavir 4-Hydroxy Analog Lopinavir M-3/M-4