Simultaneous Determination of Amlodipine and Olmesartan Using HPLC with Fluorescence Detection

sensitive, simple and rapid RP-HPLC method with fluorescence detection has been developed to simultaneously quantify amlodipine besylate (AML) and olmesartan medoxomil (OLM) in their combined pharmaceutical preparation. The method development was divided into three phases. In the first phase, a Plackett-Burman design (PBD) was used to screen five independent factors. The objective of the second phase was to optimize the method performance using a single factor design to obtain the best chromatographic performance for a short run time. Optimum separation was obtained using Lichrospher RP-18 (250 mm × 4.6 mm × 5 μm) column in the isocratic mode using a mobile phase of methanol and 5mM sodium dihydrogen phosphate buffer pH 2.5 (60:40, v/v). The flow rate was maintained at 1.2 mL/min and the detection was performed with a fluorescence detector set at 417 nm (λ emission ) after excitation at 254 nm (λ excitation ). The third phase was method validation according to ICH guidelines. The method was valid in a concentration range of 175 – 325 ng/mL for AML and 250 – 1750 ng/mL for OLM. The proposed method was successfully applied for analysis of the binary mixture of two drugs in their combined pharmaceutical formulation.