Objective To establish a ultrahigh-performance liquid chromatography-orbitrap high-resolution mass spectrometry(UHPLC-Orbitrap HRMS)method for the determination of the genotoxic impurity N-nitroso propranolol(NPPN)in propranolol hydrochloride sustained-release tablets.Methods The test sample was ultrasonically extracted using methanol as the solvent,then centrifuged and filtered before injection analysis.Chromatographic separation was performed using a 2.7 μm particle size C18 UHPLC column with a mobile phase of 0.1％formic acid(A)in water and 0.1％formic acid(B)in acetonitrile,using gradient elution.Mass spectrometry was conducted with an HESI ion source in positive ion parallel reaction monitoring(PRM)scan mode,monitoring the NPPN fragment ion at m/z 72.080 8,and quantification was performed using the standard curve method.Results The calibration curve was in good linearity in the range of 0.51-20.30 ng·mL-1 with excellent correlation coefficient(r)of 0.9999.The recoveries of NPPN at three levels(low,medium,and high)were in the range of 95.4％～98.3％,while the RSDs were from 2.5％to 4.2％.The limit of detection(LOD)was 0.20 ng·mL-1 while the limit of quantitfication(LOQ)was 0.51 ng·mL-1.This analytical method was used to determine NPPN in six batches of propranolol hydrochloride sustained release tablet samples.NPPN was detected in all six samples,among which the detection amount of 3 batches have exceeded the acceptable limit.Conclusion This method is sensitive,accurate,and fast,making it useful for pharmaceutical companies in controlling production processes and providing robust technical support for regulatory authorities.

Objective To establish a ultrahigh-performance liquid chromatography-orbitrap high-resolution mass spectrometry(UHPLC-Orbitrap HRMS)method for the determination of the genotoxic impurity N-nitroso propranolol(NPPN)in propranolol hydrochloride sustained-release tablets.Methods The test sample was ultrasonically extracted using methanol as the solvent,then centrifuged and filtered before injection analysis.Chromatographic separation was performed using a 2.7 μm particle size C18 UHPLC column with a mobile phase of 0.1％formic acid(A)in water and 0.1％formic acid(B)in acetonitrile,using gradient elution.Mass spectrometry was conducted with an HESI ion source in positive ion parallel reaction monitoring(PRM)scan mode,monitoring the NPPN fragment ion at m/z 72.080 8,and quantification was performed using the standard curve method.Results The calibration curve was in good linearity in the range of 0.51-20.30 ng·mL-1 with excellent correlation coefficient(r)of 0.9999.The recoveries of NPPN at three levels(low,medium,and high)were in the range of 95.4％～98.3％,while the RSDs were from 2.5％to 4.2％.The limit of detection(LOD)was 0.20 ng·mL-1 while the limit of quantitfication(LOQ)was 0.51 ng·mL-1.This analytical method was used to determine NPPN in six batches of propranolol hydrochloride sustained release tablet samples.NPPN was detected in all six samples,among which the detection amount of 3 batches have exceeded the acceptable limit.Conclusion This method is sensitive,accurate,and fast,making it useful for pharmaceutical companies in controlling production processes and providing robust technical support for regulatory authorities.

Objective To investigate the effect of CYP3A5 and MDR1 gene polymorphisms on blood concentration of tacrolimus and creatinine level in uremic patients during the early phase after kidney transplantation in real clinical practice. Methods 131 patients who underwent kidney transplantation for the first time with triple immunotherapy based on tacrolimus in single-center from 2013 to 2017 were enrolled for retrospective study. Tacrolimus daily dose, blood concentration, blood concentration-to-dose ratio, and serum level were compared according to the various genotypes of CYP3A5 and MDR1 polymorphisms in renal transplantation recipients, respectively. Results The dosage of tacrolimus in CYP3A5*3/*3 (GG) kidney transplantation recipients within 4 weeks after kidney transplantation was lower than those of CYP3A5*1/*1 (AA) and CYP3A5*1/*3 (AG). The serum creatinine levels of patients whose tacrolimus concentration in the range of 10-13 ng/ml were close to the normal value. Conclusion CYP3A5 gene polymorphism affects the blood concentrations of tacrolimus in renal transplant recipients. No association has been found between the blood concentrations of tacrolimus and MDR1 gene polymorphism. Tacrolimus concentration in the range of 10-13 ng/ml might contribute to restore the early kidney graft function.