Validated chromatographic methods for determination of hydrochlorothiazide and spironolactone in pharmaceutical formulation in presence of impurities and degradants.

Two specific, sensitive, and precise stability indicating chromatographic methods have been developed, optimized, and validated for Hydrochlorothiazide (HCT) and Spironolactone (SPR) determination in their mixtures and in presence of their impurities and degradation products. The first method was based on thin layer chromatographic (TLC) combined with densitometric determination of the separated spots. The separation was achieved using silica gel 60 F(254) TLC plates and ethyl acetate-chloroform-formic acid-triethyl amine (7:3:0.1:0.1, by volume) as a developing system. Good correlations were obtained between the integrated peak area of the studied drugs and their corresponding concentrations in different ranges. The second method was based on the high-performance liquid chromatography with ultraviolet detection, by which the proposed components were separated on a reversed phase C(18) analytical column using gradient elution system with deionized water-acetonitrile (97:3, v/v) for 8 min. Then acetonitrile was successively increased to 35% in the next 2 min, and kept constant in the following 10 min, finally 3% acetonitrile was regained again to stabilize the chromatographic system. The flow rate was maintained at 2 mL/min and the detection wavelength was at 230 nm. Linear regressions were obtained in the range of 4.0-50 μg/mL and 5.0-50 μg/mL for both HCT and SPR, respectively. Different parameters affecting the suggested methods were optimized for maximum separation of the cited components. System suitability parameters of the two developed methods were also tested. The suggested methods were validated in compliance with the ICH guidelines and were successfully applied for determination of HCT and SPR in their commercial tablets. Both methods were also statistically compared to each other and to the reported method with no significant difference in performance.