Study On Impurity Of New Type Of Thrombin Inhibior Dabigatran Etexilate Mesylate

Dabigatran capsule,a new thrombin inhibitor,was developed by Boehringer Ingelheim in Germany.It was first listed in Germany and the UK in 2008,and was approved by FDA in 2010.It is used to prevent deep vein thrombosis and pulmonary embolism after artificial joint replacement.Compared with warfarin,which is a traditional oral anticoagulant,it does not need routine monitoring of INR(International standardized ratio)and has a lower risk of bleeding due to adverse reactions.Dabigatran ester has broken warfarin’s monopoly on oral anticoagulant market for 50 years.It is the first brand-new oral anticoagulant drug on the market in 50 years.Its market prospect is incalculable.In this study,impurities in a synthetic route of dapigatron mesylate were investigated.The analytical methods of impurities were developed by using routine technologies,such as high performance liquid chromatography and gas chromatography.The impurities were controlled comprehensively from four aspects:organic impurities,inorganic impurities,residual solvents and gene toxic impurities,so as to ensure the safety of the drug.The full text consists of six chapters.The main contents are as follows:The first chapter introduces the background and significance of the investigation.It includes a brief introduction of venous thrombosis and pulmonary embolism,the research progress of anticoagulants,the mechanism and clinical research.In addition,the synthesis path involved in impurity research,the analytical method used in impurity detection,and the significance and content of this project.The second chapter concerns the establishment of the method for the determination of related substances of dabigatran etexilate mesylate by high performance liquid chromatography.By adjusting the elution gradient of mobile phase,choosing the appropriate solvent and sample volume,the main peaks of impurities amiprid-C6,imidazole-OH,A～F and dabigatran etexilate can be completely separated.At the same time,the detection wavelength can be selected to make the impurities detection sensitive.The methodological validation showed that the main peaks of amidine-C6,imidazole-OH,A～F and dabigatran etexilate had good linear relationship,high sensitivity and precision,and the recovery was between 95.0% and 105.0%,which met the requirements;the test solution and the control solution of the related substances were stable within 24 hours;the method has good durability by changing column temperature,detection wavelength,flow rate and p H of mobile phase A,and using different brands of chromatographic columns.Finally,three batches of dapigatron mesylate samples were tested.The contents of amidine-C6,imidazole-OH and A～F were within the required limits.The third chapter is to establish a method for the determination of residual solvents of dabigatran etexilate mesylate by gas chromatography,so that ethyl acetate,n-heptane,acetone and toluene can be completely separated.Then the method was validated.The blank solvent N,N-dimethylacetamide had no effect on the detection of residual solvents.The linear relationship between ethyl acetate,n-heptane,acetone and toluene was good,and the sensitivity and precision were high.The recovery rate was between95.0% and 105.0%,which met the requirements.After that,three batches of dapigatron mesylate samples were analyzed by this method.No ethyl acetate,n-heptane,acetone and toluene were detected in the three batches.In the forth chapter,the method for analyzing inorganic impurities of dabigatran etexilate mesylate was established.Inorganic impurities were controlled by burning residue and heavy metals.Three batches of dapigatron mesylate samples were tested,heavy metals were less than 0.001% and the burning residue was less than 0.1%.The fifth chapter is to establish a method for the detection of genotoxic impurities of dabigatran etexilate mesylate such as methyl mesylate,ethyl mesylate and isopropyl mesylate.Due to the long-term drug use and high daily dose(300 mg),according to the TTC control strategy of gene toxicity impurity(<1.5 μg/day),the limit of gene toxicity impurity content in the prepared samples of dabigaryl mesylate is very low(methyl mesylate,ethyl mesylate and ethyl propyl mesylate are all less than 0.00003%).The conventional FID(hydrogen flame ionization detector)for gas chromatography method can not achieve the detection sensitivity required.Therefore,the derivatization method was used to derive methyl mesylate,ethyl mesylate and isopropyl mesylate into iodomethane,iodoethane and isopropyl iodide by adding excessive potassium iodide and ECD(electronic capture detection)detection was used.Firstly,methods were developed to optimize the headspace equilibrium temperature and time by choosing appropriate carrier gas flow rate,shunt ratio and dissolving solvent,so that the sensitivity of derivatives of gene toxic impurities could reach the highest level and the resolution could meet the requirements.The methodological validation showed that the linear relationship between methyl mesylate,ethyl mesylate and isopropyl mesylate was good,the sensitivity was high and the precision was good.The recovery rate was between 85.0% and 105.0%,and the recovery rate was good.Three batches of dabicarbonate mesylate samples were detected by this method.The contents of methyl mesylate in three batches were 0.00001%、0.000006%、0.00001%,respectively.The contents of ethyl mesylate were 0.000003%、0.000002%、0.000011% respectively.Isopropyl mesylate was not detected.The sixth chapter is a summary.The impurities produced by a synthetic route of dapigallate mesylate were studied,including organic impurities,inorganic impurities,residual solvents and gene toxic impurities.At present,there is no pharmacopoeia for the determination of impurities in dapigatron mesylate.Only some literatures have reported the detection methods of related substances separately,but they are different from the impurities produced by the synthetic route in this study.In this work,the impurities produced are controlled comprehensively,the appropriate detection methods are developed and validated by methodology.The methods are accurate and reliable.This investigation provides an impurity control method for synthesis pathway,which can also be used as a reference for other synthetic pathways.