Aim. A rapid and reproducible HPLC method has been developed for the determination of amlodipine in experimental combined dosage forms containing amlodipine, bisoprolol and enalapril and for drug dissolution studies.
Materials and methods. The separation was done using a column Phenomenex Polar Synergi, 5 μm, 4.6×50 mm and a mobile phase of methanol:phosphate buffer solution (65:35, v/v), flow-rate of 1.0 mL/min. The injection volume was 100 μL and the ultraviolet detector was set at 240 nm.
Results. The method was validated as per ICH guidelines. Under these conditions, amlodipine was eluted at 1.89 min. Total run time was shorter than 2.5 min. The linearity of the method had a good correlation with concentration and peak area. The correlation coefficient of amlodipine was found to be not less than 0.9991, which indicates good linear relationship over concentration range 0.625 mg/mL–5.000 mg/mL (1.250 mg/mL–5.000 mg/mL at pH 4.5). The % RSD values in intra-day and inter-day precision study were found to be less than 0.267 for amlodipine, which indicate method was precise. Hence, the present developed method was said to be suitable for the analysis of drugs in their pharmaceutical dosage form. Also, in vitro dissolution of amlodipine containing tablets were performed to validate the suitability of the proposed method. The dissolution pattern complies with the FDA standards, indicating suitability of the proposed method for the dissolution study of amlodipine. It will allow conducting comparative studies in vitro to confirm the equivalence of tablets containing amlodipine.
Conclusion. A simple and sensetive HPLC method was developed for the estimation of amlodipine in tablets containing amlodipine, enalapril and bisoprolol. The proposed method was applied successfully for quality control assay of amlodipine in experimental tablets and in vitro dissolution studies. In vitro / in vivo correlation of amlodipine has been conducted.
Validated stability indicating RP-HPLC method for simultaneous determination and in vitro dissolution studies of thiocolchicoside and diclofenac potassium from tablet dosage form
