Development of Capillary Electrophoresis Technique for Simultaneous Measurement of Amlodipine and Atorvastatin from Their Combination Drug Formulations

Abstract A simple, accurate, precise, and sensitive capillary electrophoresis (CE) technique coupled to a diode array detector (DAD) has been developed for the separation and simultaneous determination of amlodipine (AM) and atorvastatin (AT) from their combination formulations. The proposed method utilized fused silica capillary (50 cm × 75 µm ID) and background electrolyte (BGE) composed of phosphate buffer (pH 6.5, 25 mM)-methanol, (80:20, v/v). The separation was achieved at 15 KV applied voltage and 25°C. Losartan was chosen as the internal standard to guarantee a high level of quantitative performance. The two drugs were subjected to thermal, photolytic, hydrolytic, and oxidative stress conditions and the stressed samples were analyzed by the proposed method. The method has shown adequate separation for AM and AT from its main degradation products (UK-55-410) & (PD 0162910-00), respectively, which demonstrated the specificity of the assay. The described method was linear over the range of 1 – 50 µg/mL (r = 0.9998) for both drugs (2.4 × 10−6 − 1.2 × 10−4 M for AM and 1.8 × 10−6 −8.6 × 10−5 M for AT). Intra- and inter-day RSD (n = 6) was ≤2.2%. The limits of detection for AM and AT were 0.5 µg/mL. The percentage recoveries (n = 6) of the two drugs from their tablet formulations were 99.97 ± 1.84 and 100.96 ± 1.12, respectively. Degradation products produced as a result of stress studies did not interfere with the detection of AM and AT and the assay can thus be considered stability indicating.