Development and validation of a liquid chromatographic method for purity control of clopidogrel-acetylsalicylic acid in combined oral dosage forms.

A reversed phase liquid chromatographic method with UV detection for the simultaneous determination of clopidogrel and acetylsalicylic acid and their related substances in combined oral formulations was developed and validated. Good separation was achieved on a Luna C18 column (150 mm × 4.6 mm, 3 μm) using gradient elution at a flow rate of 1 mL/min and a column temperature of 35 °C. UV detection was performed at 220 nm. The validation was performed according to the ICH guidelines. The method proved to be specific, sensitive (LOQ=0.975 μg/mL and 0.0384 μg/mL for clopidogrel and acetylsalicylic acid, respectively), linear in the concentration range from LOQ to 325 μg/mL for clopidogrel and from LOQ to 650 μg/mL for acetylsalicylic acid, precise (RSD values for intermediate precision <1%) and accurate with mean recovery values of 100.7% and 100.2% for clopidogrel and acetylsalicylic acid, respectively. Moreover, the solution stability and method robustness were examined. The method gives satisfactory separation of impurities of clopidogrel and acetylsalicylic acid and so it is suitable for quantification of the related substances as well as for the assay of the actives.