Optimization Of The Analysis Method For The Impurity Profile Of Penicillin Based On The Analytical Quality By Design Concept

Penicillins are a kind of antibiotic drugs widely used in clinic.As their structures are unstable,they are easy to produce a large number of impurities,which can reduce the efficacy of API and result in serious allergic reactions.Therefore,the establishment of the impurity profile of penicillins is instrumental to ensure the safety of them.To establish the impurity profile,the related substances of penicillins should be seperated first.However,the large number of impurities with different properties makes it difficult.At present,15 kinds of penicillins are present in the Chinese Pharmacopoeia.There are two shortcomings in the separation methods of them: 1.Penicillins have similar chemical structures,however,there are great differences in the analytical methods of their related substances in the Chinese Pharmacopoeia.The current situation of "thousands of drugs with thousands of methods" leads to great differences in the type and quantity of impurities.There is no unified standard,and there is no reference to each other,so the establishment of method is time-consuming.2.The methods in Chinese Pharmacopoeia are not effective in separating the related substances of some penicillins,and some of the related substances can not be separated.In order to solve the above two problems,a strategy of using a universal method to separate the substances of penicillins was proposed.If the related substances of many kinds of penicillins can be well separated by one analytical method,this method can be used as a universal method to establish the impurity profile of many kinds of penicillins.However,due to the structural differences of different penicillins,although most of the impurities can be well separated by the universal method,there are still some impurities that can not be separated totally.The universal method is still not the optimal separation method for each variety.It should be further optimized according to the differences of different varieties.Based on the previous work of our laboratory,it has been proved that the analytical method of related substances of penicillin sodium in the 2015 edition of Chinese Pharmacopoeia is universal for the separation of most kinds of penicillins.At present,the problem is to further optimize the universal method,get the optimal separation of different varieties,and summarize the commonness of optimizing the universal method,so as to improve the strategy of universal method for the separation of penicillins.The concept of Quality by Design(Qb D)has been widely used in the establishment and optimization of analysis methods,known as Analytical Quality by Design(AQb D).As an important part of AQb D,Design of Experiment(Do E)can evaluate multiple influence factors and the interaction of them at the same time,and according to statistic data,scientifically evaluate the risk of each stage of the experiment,we can get the design space(DS),to ensure the robustness of the method.It is the optimal choice and future trend of analysis method optimization.In this paper,based on the AQb D concept,oxacillin and chloroxacillin were selected as examples to optimize the universal method.According to the optimization process and results,the general process of optimizing the universal method for different varieties was discussed,and the commonness of the optimization process was summarized in order to provide reference for the optimization of other penicillin varieties.Finally,the optimized method can achieve better separation of the above three varieties compared with the methods in pharmacopoeia.More impurities can be separated,and the symmetry of the chromatographic peak is better.The methodology of the optimized method is verified,and it is proved that the methods have good robustness,precision,accuracy and repeatability.With the help of LC-MS,the structures of impurities are analyzed,which helps to track the impurity peak.Using the optimized method to analyze the real samples of the three kinds of penicillins,it was found that the impurities in the real samples can be well separated,and the product quality can be effectively controlled by this method.