Objective To investigate the stability of adefovir dipivoxil tablet and determine the expiry date.Methods Ac-cording to the Collection of Preclinical Guidelines for new Drugs,under market packing circumstances,the quality indexes of adefovir dipivoxil tablet such as shape and properties and content determination,were periodically checked in the storage time of 12 months.Results All the indexes conformed to regulations of its quality standard.Conclusion Adefovir dipivoxil tablet has high and stable quality after it is kept for 12 months in room temperature,so the shelf life of the tablet is defined as 12 months.

Objective To develop an high performance liquid chromatography method for the determination of adefovir dipivoxil in adefovir dipivoxil tablets.Methods The chromatographic equipment includeds pump HP1100,inspection instrument HP1100,chemical analytical station HP,and a mobile phase composed of acetonitrile-water(40 ∶ 60) solution with 1% triethylamine and 50 mmol/L potassium dihydrogen phosphate(adjusted to pH 3.0 by phosphoric acid).The flow rate was 1.0 ml/min and monitered at 260 nm.The column temperature was room temperature.Results The calibration curves of adefovir dipivoxil showed a good linear relation over the range of 4.04-50.50 μg/ml(r=0.9999).The average recovery of adefovir dipivoxil was 99.77% and RSD was 0.24%.Conclusion This method is simple,accurate and with good reproducibility.It can be used for the determination of adefovir dipivoxil in adefovir dipivoxil tablets.