Study On The Detection Of Related Substance In Levocetirizine Dihydrochloride

The method of Cetirizine Hydrochloride have been registered in USP,BP,EP and Chp,but Levocetirizine Dihydrochloride is only using in USP.According to the detection method of Cetirizine and Levocetirizine Dihydrochloride,The requirements can not met the requirements in the domestic ordinary silica gel column chromatography.It has been reported that the Levocetirizine Dihydrochloride is refined from the cetirizine in the last synthesis step.They have the same raw materials and the possible related substances.The paper is to establish the method of the related substances of Levocetirizine Dihydrochloride using the impurities of Cetirizine EP RS for the Chinese currently widely used chromatographic column and chromatographic conditions to achieve separation at the same time requirements,the classification of impurities.It has been studied that the mobile phase of different acidity,organic phase ratio,column durability,flow rate,column temperature,mobile phase by the radient elution program to determine the changes of the impurities under different conditions,and the method of Levocetirizine Dihydrochloride and 9 impurities is be established,the new method uses 0.7%phosphoric acid solution and acetonitrile,C18 chromatographic column to carry out gradient elution of the 10 substances,and the degree of separation of each material is good.The oxidation,0.1mol/Lhydrochloric acid,0.1mol/Lsodium hydroxide,high temperature with 60 ?,and UV light damage tests have been carried out.The type and quantity of impurities of the levocetirizine hydrochloride placed 20h did not increase when the temperature was 60 ?;Increasing 6%when it was destroyed by alkali for 6h;he peak of unknown impurity by acid damage for 3h impurity have changed to levocetirizine hydrochloride again after 6h;and 1%hydrogen peroxide oxidation of 3min and UV after 30min levocetirizine hydrochloride degradation peak reached 50%,which is mainly oxidation of unknown impurities,UV damage is mainly F,G,B,impurity C and 4-CBH increasing,levocetirizine hydrochloride complete degradation after 4h,unknown impurities near the peak of dissolution in the process of increasing.The methodology been validated detective the Levocetirizine Dihydrochloride and the results meet the requirements The limits of cetirizine hydrochloride were determined.