Original Article

Development and validation of an HPLC method using an experimental design for analysis of amlodipine besylate and enalapril maleate in a fixed dose combination


  • Alptug KARAKUCUK
  • Zeynep Safak TEKSIN

Received Date: 05.05.2020 Accepted Date: 29.06.2020 Turk J Pharm Sci 0;0(0):0-0 [e-Pub]


The aim of this study was development and optimization a simple, cost-effective, and robust HPLC method with the experimental design approach in the assay and dissolution analysis of amlodipine besylate and enalapril maleate from a fixed-dose combination tablet.

Materials and Methods:

The chromatographic analysis was performed on a C18 column (4.6 x 250 mm id., particle size of 5 μm). The injection volume was 5 μL and detection wavelength was 215 nm. The Box-Benkhen design was used to test robustness of the method. Flow rate (1, 1.2, and 1.4 mL/min), column temperature (25oC, 30oC, and 35oC), methanol ratio of the mobile phase (5, 10, and 15%), and pH of the mobile phase (2.8, 3, and 3.2) were selected as independent variables. The validation of the method was carried out according to ICH guidelines. Dissolution of the tablets was performed by using USP apparatus 2 and analysed using the optimized HPLC method. Multivariate linear regression analysis and ANOVA was used in the statistical evaluation.


Linear models were fitted for all variables. The flow rate was the most significant factor affecting the API’s concentrations. The optimized method included following parameters: 25oC of column temperature, 10% of methanol ratio in the mobile phase, 2.95 of pH and 1.205 mL/min of flow rate. Retention times were 3.8 min and 7.9 min for enalapril and amlodipine, respectively. The method found to be linear in a range of 0.8-24 μg/mL (R2>0.999) and 1.6-48 μg/mL (R2>0.999) for amlodipine and enalapril, respectively. Both active substances were dissolved more than 85% within 10 minutes.


Experimental design was found a useful tool for determination and separation of enalapril maleate and amlodipine besylate in dosage forms. It was shown that the optimized method can be used for in vitro performance and quality control tests of fixed dose tablet combinations containing enalapril maleate and amlodipine besylate.

Keywords: Amlodipine, Enalapril, design of experiment (DOE), HPLC, fixed dose combination (FDC)