Abstract: The experiment was aimed to establish a method for determining the content of praziquantel in praziquantel injection and investigate its stability.HPLC method was used to determine the content of praziquantel.HPLC analysis was carried out using a Diamonsil C18 column (150 mm×4.6 mm,5μm) with ultraviolet detector at a wavelength of 210 nm.The column temperature was 25℃.The mobile phase,a mixture of acetonitrile and water (60:40) with the flow rate of 1.0 mL/min.The injection volume was 20μL.Stability of praziquantel injection was studied by stress test,accelerated stability test and long-term stability test.Excellent line relationship was obtained in the range of 6.037 to 90.555μg/mL (R²=0.9993).The average recovery was 99.24% and RSD was 0.77%.The average content of praziquantel injection (percent of the labeled amount) was 100.3%.Praziquantel injection was stable to temperature (60℃) and unstable to light (4500 lx±500 lx) during 10 days in stress test.No obvious changes of the appearance and content of praziquantel injection were observed during 6 months in accelerated test and 24 months in long-term stability test.The results suggested that the established method was simple,sensitive and accurate with good repeatability,which could be used for quality control of praziquantel injection.It could be forecasted that praziquantel injection was stable and its period of validity was two years stored under room temperature (25℃) and away from light.

Key words: praziquantel injection; determination; stability; HPLC