Introduction: Trace amount of impurity may influence the efficacy and safety of the pharmaceuticals, which requires comprehensive analysis of the impurities generated during the manufacturing, transportation and storage. Characterization and quantification of structurally related peptide impurities is a crucial task in pharmaceutical development, these impurities include amino acid sequences related to, but different from, that of the active ingredient, as a result of insertion, deletion, oxidation, or D-amino acid racemization to the amino acid sequence. Semaglutide is rDNA origin, glucagon-like peptide-1 (GLP-1) agonist, approved for the treatment of type II diabetes mellitus (Rybelsus and Ozempic) and weight management (Wegovy) in overweight adults with certain conditions. Under the guideline issued by Food and Drug Administration (FDA), ANDAs for Certain Highly Purified Synthetic Peptide Drug Products That Refer to Listed Drugs of rDNA Origin Guidance for Industry, we are exploring a synthetic Semaglutide that is intended to be a “duplicate” of the approved rDNA origin Semaglutide. Thus, we should identify each peptide-related impurity that is 0.10 percent of the drug substance or greater for Semaglutide covered by this guidance. Among others, low-level D-amino acid degradation impurities are always the most challenging ones for characterization. Herein, we report an accurate, straightforward, and low limit of detection method for the characterization of low-level D-amino acid degradation impurities in synthetic Semaglutide as well as other potential low-level degradants.
Methods: During the formulation-accelerated stability study, multiple unknown isomeric degradants were found both in generic Semaglutide and originator. Using reverse-phase high-performance liquid chromatography (RP-HPLC) to separate the degradants, followed by tandem mass spectrometry to
determine the mass value of the degradants existed in both formulations. After target D-amino acid degradant off-line collection, the sample went through lyophilization, deuterated hydrochloric acid (D-HCl) hydrolyzation, chiral derivatization with low level D/L type amino acid shifting suppression substrates, RP-HPLC tandem mass spectrometry analysis of different amino acids comparing with D/L amino acids standards, the whole process ended with data analysis and conclusion being made.
Results: Through this study we have successfully characterized D-Ser, D-His and D-Asp Semaglutide degradants. The novelty of this research is applying specific substrates during the D-HCl hydrolyzation of the collected degradants, which can suppress the D/L amino acid shifting at nanogram per milliliter concentration. Along