Determination of Related Substances in Candesartan Cilexetil and Amlodipine Tablets by HPLC

OBJECTIVE To establish an HPLC method for determining the related substances and decomposition products in Candesartan Cilexetil and Amlodipine tablets. METHODS An Inertsil ODS-SP C₁₈ column was used with the mobile phase of 0.035 mol·L^-1 sodium dihydrogen phosphate (pH 3.0)-acetonitrile-methanol by gradient elution at the detection wavelength of 238 nm. RESULTS The impurities were well separated from candesartan cilexetil and amlodipine. Candesartan cilexetil impurity B is the biggest one. The total content of related substance were <0.5%. CONCLUSION The method is simple, selective, accurate and reproducible. It is suitable for determination of related compounds in Candesartan Cilexetil and Amlodipine tblets.