Development and validation of a stability-indicating assay method for simultaneous determination of perindopril and indapamide in combined dosage form by reversed-phase high-performance liquid chromatography.

An approach of forced degradation study was successfully applied for the development of a stability-indicating assay method for simultaneous determination of perindopril and indapamide in a formulation in the presence of its degradation products. The method showed adequate separation of perindopril and indapamide from their associated main impurities and degradation products. Separation was achieved on an XTerra RP18, 5 microm, 150 x 4.6 mm id column at 55 degrees C by using the mobile phase NaH2PO4 buffer (pH 2.0; 0.005 M)-acetonitrile (75 + 25, v/v) at a flow rate of 1 mL/min and UV detection at 215 nm. Comprehensive stress testing of perindopril and indapamide was carried out according to the International Conference on Harmonization (ICH) guideline Q1A (R2). The specificity of the method was determined by assessing interference from the placebo and by stress testing of the drug (forced degradation). The drug was subjected to acid hydrolysis, base hydrolysis, oxidation, dry heat, and photolysis to apply stress conditions. There were no other coeluting, interfering peaks from excipients, impurities, or degradation products due to variable stress conditions, and the method was specific for determination of perindopril and indapamide in the presence of degradation products. The method was validated in terms of linearity, precision, accuracy, specificity, robustness, and solution stability. The linearity of the proposed method was investigated in the range of 24-56 microg/mL (r2 = 0.9993) for perindopril and 7.5-17.5 microg/mL (r2 = 0.9992) for indapamide. Degradation products produced as a result of stress studies did not interfere with the detection of perindopril and indapamide, and the assay can thus be considered stability indicating.