ABSTRACT
Since the stability of the pharmaceuticals plays a crucial role in efficacy and safety while using them in the treatment of disorders, the evaluation of purity and impurity profiling of pharmaceuticals is of utmost importance using efficient analytical techniques. The present study explains the identification, isolation, and characterization of stress degradation products of the anti-human immunovirus drug Darunavir. The degradation study was performed to evaluate the stability profile of Darunavir in different stress conditions like hydrolytic, oxidative, thermal, and photolytic conditions as per the ICH guidelines. Degradation products were identified using ultra-performance liquid chromatography coupled with mass spectrometry, isolated using semi-preparative high-performance liquid chromatography, and structural characterization by HRMS and 1H, 13C NMR (1D, 2D). Darunavir is relatively stable in oxidative, thermal, and photolytic conditions; however, considerable degradation was observed in acid and base hydrolysis. A total of five degradation products were identified and isolated in acid and base degradation. DP-1, DP -2, & DP-3 were observed in acid conditions, whereas in base conditions, along with DP-2, two more DPs, i.e., DP-4 & DP-5, were identified. Among the five DPs, two degradation products, namely DP-1: N-(4-(N-(3-amino-2-hydroxy-4-phenylbutyl)-N-isobutylsulfamoyl) phenyl) acetimidamide. & DP-3: hexahydrofuro[2,3-b]furan-3-yl(4-((4-acetimidamido-N-isobutylphenyl)sulfonamido)-3-hydroxy-1-phenylbutan-2-yl)carbamate, are novel, remaining degradation products DP-2: 4-amino-N-(3-amino-2-hydroxy-4-phenylbutyl)-N-isobutylbenzenesulfonamide, DP-4: 4-amino-N-(((5S)-4-benzyl-2-oxooxazolidin-5-yl) methyl) -N-isobutyl benzenesulfonamide and DP-5: methyl ((3S)-4-((4-amino-N-isobutylphenyl) sulfonamido)-3-hydroxy-1-phenylbutan-2-yl) carbamate are already reported tentatively using a single analytical technique coupled with mass analysis without any evidence from NMR and IR data. Hence, the present study focused on using High-Resolution Mass, 1D, and 2D 1H, 13C NMR data for concrete confirmation of structures for degradation products. Supplementary Information: The online version contains supplementary material available at 10.1007/s10337-022-04226-z.
ABSTRACT
RATIONALE: Losartan potassium (losartan) is the most frequently utilized antihypertensive medication in the world. However, partial oxidation of losartan produces toxic by-products that could be harmful to living organisms. Therefore, it is necessary to degrade the losartan and identify the potential toxic oxidative degradation products to minimize their formation during manufacturing, formulation, storage, and packing conditions. METHODS: Oxidative degradation experiments of losartan were performed according to ICH guidelines. The degradation products were detected using ultra-high-performance liquid chromatography-mass spectrometry analysis, isolated by using preparative HPLC, and identified by using high-resolution mass spectrometry and nuclear magnetic resonance spectroscopic techniques. RESULTS: The degradation products (DP-1, DP-2, and DP-3) were identified as (((2'-(2H-tetrazol-5-yl)-[1,1'-biphenyl]-4-yl)methyl)amino)-2-oxoethylpentanoate, 5-(4'-((2 butyl-4-chloro-5-(hydroxymethyl)-1H-imidazol-1-yl)methyl)-[1,1'-biphenyl]-2-yl)-1H tetrazol-1-ol, and 5-(4'-((2-butyl-4-chloro-5-(hydroxymethyl)-1H-imidazol-1 yl)methyl)-[1,1'-biphenyl]-2-yl)-2H-tetrazol-2-ol, respectively. CONCLUSIONS: Forced degradation of losartan potassium API under oxidative condition indicates the formation of two major novel oxidative degradation products (DP-2 and DP-3) and one minor known degradation product (DP-1).Preparative HPLC used for the isolation of the resultant DPs and their structures were successfully established using UHPLC-MS, 1H NMR, 13C NMR, HSQC, HMBC, and HRMS spectroscopic techniques.
