Ritonavir Impurity M

Ritonavir Impurity M is a structurally related synthetic byproduct arising from the incomplete alkylation step during Ritonavir manufacturing. It retains the core dipeptide scaffold of the parent drug but features an unmodified 3-hydroxy-4-phenylbutyric acid moiety, lacking the N-methyl substitution at the P2 position. This impurity exhibits a distinct UV absorption profile due to the exposed hydroxyl group, enabling differentiation via HPLC-UV. Its precise application includes serving as a reference standard for quantifying alkylation efficiency in process validation.