Study On Quality Control Methods Of Terbutaline Sulfate

Terbutaline sulfate is a selective fast-acting ?2-adrenoceptor agonists,which is used in the treatment of bronchial asthma and other lung diseases associated with bronchospasm.It can also be used to prevent preterm labor and fetal asphyxia.It is a promising drug with high selectivity,less side effects and has been widely used at home and aboard.In view of the shortcomings of current quality control methods of terbutaline sulfate,the key factors which affect the safety and effectiveness were studied in this study,including residual solvent,process impurities and degradation products,and the content.It provides new methods and references for the quality evaluation and control of terbutaline sulfate.In the present study,a headspace gas chromatography(GC)method for the simultaneous determination of 10 residual solvents including methanol,ethanol,acetone,methyl tert-butyl ether,ethyl acetate,tetrahydrofuran,benzene,acetic acid,toluene and benzyl chloride in terbutaline sulfate has been developed based on a comprehensive analysis of the solvents used in the synthesis of terbutaline sulfate.Also,a rapid ultra high performance liquid chromatography coupled with hybrid triple quadrupole time-of-flight mass spectrometry(UHPLC-Q-TOF-MS/MS)method has been established for the identification of process impurities and degradation products of terbutaline sulfate.Besides,a high performance liquid chromatography(HPLC)method has been developed and validated for the assay of terbutaline sulfate.Part one Simultaneous determination of 10 residual solvents interbutaline sulfate by headspace gas chromatographyObjective: To develop a headspace GC method for the simultaneous determination of 10 residual solvents in terbutaline sulfate,including methanol,ethanol,acetone,methyl tert-butyl ether,ethyl acetate,tetrahydrofuran,benzene,acetic acid,toluene and benzyl chloride.Methods: Separation was performed on a DB-624 UI capillary column(30 m×0.32 mm,1.80 ?m)using temperature programming,the column temperature was maintained at 40 °C for 3 min,then raised at a rate of 10 °C per minute to 90 °C and hold for 1 min,and finally raised at a rate of 40 °C per minute to 200 °C and hold for 5 min.The GC conditions for all analysis were as follows: the inlet temperature was 200 °C and split ratio was 5:1;Flame ionization detection(FID)was used as detector with a temperature of 250 °C;the carrier gas was nitrogen at a velocity of 1.0 mL/min.The sample oven,loop and transfer line temperatures were 90,100 and 110°C,respectively.The vial equilibration and pressurization times were 30 and 1 min,respectively.The sample injection time was 1 min.Results: 10 residual solvents were separated completely.All of the 10 residual solvents showed good linear relationships within the experimental concentrations and all correlation coefficients were no less than 0.9990;the average recoveries were in the range of 95.7-102.4%.The precision,repeatability,stability were good.The contents of methanol,ethanol and acetone in 3 samples were 0.035-0.043%,0.033-0.034% and 0.00059%-0.00062%,respectively.While the contents of methyl tert-butyl ether,ethyl acetate,tetrahydrofuran,benzene,acetic acid,toluene and benzyl chloride were all below the detection limits.Conclusions: The established method is simple,accurate and sensitive.It can be used for the determination of the residual solvents in terbutaline sulfate.Part two Identification of process impurities and degradation products from terbutaline sulfate by UHPLC-Q-TOF-MS/MSObjective: To identify process impurities and degradation products of terbutaline sulfate by the rapid ultra high performance liquid chromatography coupled with hybrid triple quadrupole time-of-flight mass spectrometry(UHPLC-Q-TOF-MS/MS)method.Methods: Firstly,the fragmentation pathway of terbutaline sulfate was studied.Terbutaline sulfate was subjected to long-term storage and stress degradation conditions of hydrolysis(acidic,neutral and alkaline),oxidation,thermal,humidity and photolysis.All the degraded samples were analyzed by UHPLC-Q-TOF-MS/MS.The separation was achieved on a phenomenex luna C18(2.0 mm×150 mm,3 ?m)column using mobile phase composed of ammonium formate buffer(10 mmol/L,pH 3.2)and methanol in gradient elution mode.The mobile phase flow rate was set at 0.3 mL/min and the injection volume was 5 ?L.Q-TOF-MS/MS experiments were conducted with Duo-SprayTM sources in the positive electrospray ionization(ESI)mode.A full scan was employed in MS1.Dynamic background subtract(DBS)was used to trigger the IDA function in the experiment.For the IDA criteria,the 12 most intense candidate ions of per cycle that exceed 100 cps were selected to a production scan.The accurate mass of the degradation products and their fragments were obtained.Then,the structures of the various degradation products were elucidated using the information from mass spectrometric fragmentation and accurate mass data.Results: A total of 17 compounds including 14 novel degradation products were characterized.Amongst these,the 3 known impurities were process impurities,as well as degradation products.Conclusions: Terbutaline sulfate is susceptible to oxidative,alkaline hydrolytic and alkaline photolytic conditions and the most susceptible positions for degradation in the molecule are the secondary amine function,benzyl alcohol group and phenylethyl group.The most probable mechanisms for the formation of degradation products have been proposed for the first timePart three Improvement of the assay method for terbutaline sulfateObjective: To improve high performance liquid chromatography(HPLC)method for the assay of terbutaline sulfate.Methods: The separation was achieved on a Agilent Zorbax SB-C18(4.6 mm×150 mm,5 ?m)column using mobile phase composed of ammonium formate buffer(30 mmol/L,pH 3.0)and methanol in isocratic elution mode at a flow rate of 1.0 mL/min.The detection wavelength was 276 nm,the injection volume was 10 ?L,and the column temperature was room temperature.Results: The calibration curve was linear within the range of 0.01-0.40 mg/mL(r=1.000);the average recoveries was 99.2%,with RSD of 0.8%(n=6).The precision,repeatability,stability,limit of detection(LOD)and limit of quantification(LOQ)were fine.The contents of terbutaline sulfate in 3 samples were 100.5%,98.9% and 99.2%,respectively.Conclusions: Compared with potentiometric titration and ion-pair high performance liquid chromatography,the improved HPLC method is simpler,faster and more economical.The changes of the main impurities in the sample also can be observed from the chromatograms.It can be used for the determination of terbutaline sulfate.