Belumosudil Impurity NEW

High purity and precise structure verification：HPLC purity ≥99.0%, with the structure confirmed by 1H NMR, 13C NMR, HRMS, and infrared spectroscopy (IR), strictly complying with the quality specifications of FDA and EMA for impurity reference substances, ensuring the accuracy and reliability of analytical results.

Excellent chemical stability：Stable for up to 36 months when stored at -20°C in the dark; in an acetonitrile - water mixed solution system, the degradation rate is <1% after being placed at room temperature for 14 days, meeting the requirements of long-term quality monitoring and stability investigation.

Clear process relevance：As a characteristic impurity from condensation and methoxylation reactions in the synthesis of belumosudil hydrochloride, it can accurately identify process risks such as imbalanced raw material ratios and uncontrolled reaction conditions during the reaction process, providing key evidence for optimizing the synthesis route.

Pharmaceutical quality inspection：Used for LC-MS/MS detection of Impurity 38 in belumosudil hydrochloride APIs and formulations, strictly following ICH Q3A standards to control its content ≤0.1%, ensuring that Rho kinase inhibitor drugs meet quality standards.

Synthesis process optimization：During condensation or methoxylation reactions, by monitoring the content of this impurity (such as adjusting reaction temperature and catalyst type, reducing the impurity from 0.9% to 0.1%), reaction parameters can be optimized to effectively reduce by-product formation.

Development of detection methods：As a reference substance for methoxyquinazoline-containing impurities, it is used to establish specific detection methods, such as ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Accurate quantification is achieved using characteristic fragment ions (m/z 352.2→281.1), with a detection limit as low as LOD=0.01ng/mL.

Support for toxicological evaluation：Provides standard samples for evaluating the potential toxicity of this impurity, facilitating the conduct of in vitro cytotoxicity tests and in vivo pharmacokinetic studies, meeting the strict requirements of drug regulatory agencies for impurity safety assessment.

Innovation in detection technology：Currently, UPLC-MS/MS is the mainstream technology. Using a C18 column (1.7μm, 2.1×100mm) with 0.1% formic acid aqueous solution - acetonitrile for gradient elution, combined with the multiple reaction monitoring (MRM) mode, ultra-trace detection of this impurity can be achieved, with a limit of quantitation (LOQ) as low as 0.05ng/mL.

Analysis of formation mechanism：Studies have shown that this impurity mainly originates from the abnormal addition of 4-methoxyquinazoline intermediates and phenoxyacetamide during the condensation reaction. When the reaction temperature is too high or the catalyst activity is too strong, the impurity formation increases significantly. By introducing a weak base catalyst (such as potassium carbonate) and controlling the reaction temperature below 50°C, the impurity formation can be reduced by more than 80%.

Progress in safety evaluation：In vitro Ames tests showed that this impurity had no mutagenicity at concentrations ≤200μg/dish; however, in a 90-day long-term toxicity test in rats, mild abnormalities in liver function indicators were observed in the high-dose group (150mg/kg). Based on comprehensive toxicological data, the industry recommends setting the impurity limit at ≤0.07% to ensure the safety of clinical drug use