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Background: The current investigation entails the characterization of seven degradation products (DPs) formed in different stress conditions of gilteritinib employing liquid chromatography-tandem mass spectrometry (LC-MS/MS). Methodology: This study developed a stability-indicating reversed-phase high-performance liquid chromatographic (HPLC) method for precisely determining gilteritinib in the presence of its process-related impurities in bulk drug and formulation samples. To explore the stability profile of gilteritinib, it was exposed to forced degradation experiments conducted under various conditions, including acidic, basic, oxidative, photolytic, and thermal stress. These experiments revealed the degradation of gilteritinib under basic, acidic, and photolytic conditions, forming seven distinct DPs. Result: The chromatographic resolution of gilteritinib and its impurities along with DPs was effectively achieved using a Waters Symmetry C18 (250 mm × 4.6 mm, 5 μm) column using equal volumes of solvent A and B (pH 4.5 phosphate buffer and acetonitrile in 25:75 (v/v) as solvent A, acetonitrile and methanol in 75: 25 (v/v) as solvent B) pumped isocratically at 0.7 mL/min and 230 nm wavelength. The method produces an accurate fit calibration curve in 25-175 μg/mL for gilteritinib and LOQ (0.025 μg/mL) – 0.175 μg/mL for its impurities with acceptable precision, accuracy, and recovery. Conclusion: The efficacy of this method was validated through LC-MS/MS, which allowed for the verification of the chemical structures of newly generated degradation products of gilteritinib. Hence, this method is appropriate for the resolution and evaluation of process-related impurities of gilteritinib and can also be applied for evaluating stress degradation products.

This study aimed to propose a straightforward and highly sensitive HPLC method for the evaluation of letermovir, coupled with an examination of the stress degradation nature of letermovir. Chromatographic separation analytes were attained using a Phenomenex Luna C18 column (250 mm x 4.6 mm; 5 μm id) maintained at 35 °C. The mobile phase comprises 0.1% phosphoric acid, methanol, and acetonitrile in 45:25:30 (v/v) facilitated isocratic elution at 0.8 mL/min with 234 nm wavelength. Under the proposed conditions, retention times were determined to be 9.58 min for letermovir and 11.10 min, 4.18 min, 6.30 min, and 13.26 min for impurities 1, 2, 3, and 4, respectively. The method achieved a sensitive detection limit of 0.009 with 0.05-0.2 μg/mL as the linear range for impurities. Other validation tests met acceptable criteria for letermovir and impurities. Additionally, stress degradation tests were conducted following ICH Q1A (R2) guidelines, subjecting the drug to various stress conditions. LC-MS/MS analysis identified five degradation products (DPs), of which DP 1, 4, and 5 were formed due to acid stress, whereas DP 2, 3 and 5 were formed due to peroxide, base and UV stress respectively. The possible structure of DPs was assessed by the interpretation and correlation of mass fragment data. The validation test produces satisfactory results supporting the suitability of the method for regular analysis of letermovir and its impurities. Moreover, the method is applicable for evaluating the degradation mechanism of letermovir. [ABSTRACT FROM AUTHOR]