Extensive Study of Aspirin and Its Related Impurities Under Various Stressed Conditions in Low Dose Aspirin and Esomeprazole Magnesium Capsules

The objective of the present research work is to develop a isocratic reversed-phase liquid chromatographic (RP-HPLC) method for the determination of Aspirin in pharmaceutical pharmaceutical dosage forms for its related impurities in presence of esomeprazole. The chromatographic separation was achieved on a RP 18 column (100mm×4.6mm, 5 µm). The isocratic LC method employs mixture of buffer methanol and isopropyl alcohol in the ratio of (84:13:3 v/v) solutions as mobile phase. The buffer solution contains 6.8g of Potassium dihydrogen orthophosphate adjusted to pH 2.5 with orthophosphoric acid .The flow rate was 1.5 ml/min and the detection wavelength was 275 nm. In the developed HPLC method, the resolution between Aspirin and its potential impurity salicylic acid was found to be greater than 4.0. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation in presence of esomeprazole. Considerable degradation was found to occur in basic medium and mild degradation observed in acid hydrolysis stress conditions. Degradation product formed during acidic hydrolysis was salicylic acid. The stress samples were assayed against a qualified reference standard and the mass balance was found close to 99.5%. The developed RP-HPLC method was validated with respect to linearity, accuracy, precision and robustness.