FORCED DEGRADATION STUDY OF POST-SHELF LIFE AND MARKETED TABLETS OF AMLODIPINE BY RP-HPLC

The stability of pharmaceutical products plays an important role from the economical point of view. There are not many studies that report about the stability of drugs past their expiration dates. The objective of the current study was to determine tablet content and perform dissolution test of expired tablets of amlodipine besylate and tablets where expiry date has not exceeded and to develop simple, accurate, sensitive and stability indicating RP-HPLC method for the determination of per cent drug remained of Amlodipine besylate in the presence of its degradation products in bulk drug, expired tablets and tablets whose expiry date has not been exceeded. Drug was subjected to all stress conditions such as hydrolysis (acidic and alkaline), oxidation (3% H2O2 v/v), photolysis, thermal degradation and humidity study. Content determination was performed using spectrophotometric and RP-HPLC method; the per cent of dissolved substance from tablets during dissolution test was performed using spectrophotometric method and detection was made at 239 nm. All stressed samples were successfully analysed on C18 column using mobile phase phosphate buffer pH 3.5 (50mM): methanol: acetonitrile in the ratio of 30:60:10 v/v/v. A flow rate was maintained at 1.5 ml/min and detection was made at 240 nm. The proposed methods were validated with regard to linearity, sensitivity, and intermediate accuracy and precision. No discrepancies between the results of determination and the declared values range for all the analysed tablets were observed. The results of performed study might suggest that storage of analysed batches of tablets over time period exceeding the expiry date given by the manufacturer did not influence their contents.