Identification, Isolation and Characterization of Unknown Acid Degradation Product of Nevirapine

A Novel stability indicating RP-UPLC chromatographic method was developed for analysis of Nevirapine in pharmaceutical formulations. The developed RP-UPLC method is superior in technology to conventional RP-HPLC with respect to speed, resolution, solvent consumption and cost of analysis. Nevirapine was subjected to the stress conditions like acid, base, thermal, oxidative and photolytic degradation. Nevirapine was found to degrade significantly in acid and thermal degradation. In acid degradation relative retention time with 0.42 is found as unknown impurity. New impurity was identified, isolated using mass based auto purification system and characterized by 1H NMR (1D and 2D) and HRMS experiments. Isolated impurity was showing molecular weight of 244.10, molecular formula C12H12N4O2 and its name as 2-(3-Amino-4-methylpyridin-2-ylamino)nicotinic acid. The calibration graph was linear and the method showed less deviation in accuracy results. The test solution was found to be stable for 20 days when stored in the refrigerator between 2°C to 8°C. The developed RP-UPLC method was validated and meets the requirements delineated by the International Conference on Harmonization (ICH) guidelines. The intra-day and inter-day variation was less than 1%. The method was reproducible and selective for the estimation of Nevirapine. Because the method could effectively separate the drug from its degradation products, it can be employed as a stability-indicating method.

Identification, Isolation and Structure Confirmation of Forced Degradation Products of Sofosbuvir

A new stability indicating reverse phase chromatographic method was developed for the analysis of Heptisis C Drug Sofosbuvir. The developed UPLC method was superior in technology to conventional RP-HPLC with respect to resolution, speed, solvent consumption and analysis cost. Sofosbuvir was subjected to the thermal, hydrolytic, oxidative, and photolytic degradation, according to ICH guidelines. The drug depicted degradation in acidic, basic and oxidative conditions and it was stable to other stress conditions (thermal and photolytic). Identified degradation products were isolated using mass supported auto purification system and characterized by NMR techniques (1H NMR, D2O Exchange, 13C NMR, 31P NMR, 19F NMR, HSQC and HMBC) and HRMS experiments. Isolated acid degradation impurity was showing molecular weight of 416.08, molecular formula C16H18FN2O8P and its name as (R)-((2R, 3R, 4R, 5R)-5-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)-4-fluoro-3-hydroxy-4-methyltetrahydrofuran-2-yl)methyl phenyl hydrogen phosphate. Isolated base degradation impurity-A was showing molecular weight of 453.13, molecular formula C16H25FN3O9P and its name as (S)-isopropyl 2-((R)-(((2R, 3R, 4R, 5R)-5-(2, 4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)-4-fluoro-3-hydroxy-4-methyltetrahydrofuran-2-yl)methoxy)(hydroxy)phosphorylamino)propanoate. Isolated base degradation impurity-B was showing molecular weight of 411.08, molecular formula C13H19FN3O9 P and its name as (S)-2-((R)-(((2R, 3R, 4R, 5R)-5-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)-4-fluoro-3-hydroxy-4-methyltetrahydrofuran-2-yl)methox-y)(hydroxy)phos-phorylamino)propanoic acid. In oxidative degradation study, degradation was observed very less and with obtained quantity (less than 2 mg) recorded 1H NMR and HRMS analysis. From the spectral data degradation product was showing molecular weight of 527.15, molecular formula C22H27FN3O9P and its name as (S)-isopropyl 2-((S)-(((2R, 4S, 5R)-5-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)-4-fluoro-4-methyl-3-oxotetrahydrofuran-2-yl)methoxy)(phenoxy)phosphorylamino)propanoate. The developed chromatographic method was validated as per ICH guidelines and proved suitable for the stability testing and quality control of the drug Sofosbuvir