Stability-Indicating RP-HPLC Method for the Simultaneous Estimation of Spironolactone and Furosemide in Bulk and Combined Pharmaceutical Formulations

Research Article

Abstract

Development and validation of a rapid, precise, and stability-indicating reversed-phase high-performance liquid chromatographic method enables the simultaneous estimation of spironolactone and furosemide in bulk forms and commercial solid oral dosage units. Chromatographic resolution is successfully achieved on a reversed-phase C18 column (250 mm×4.6 mm, 5 μm) utilizing an optimized isocratic mobile phase consisting of methanol and 0.1% aqueous acetic acid (60:40 v/v). The mobile phase is maintained at a standardized flow rate of 0.7 mL/min, with spectrophotometric detection at an isosbestic wavelength of 254 nm. Under these optimized parameters, furosemide and spironolactone resolve cleanly with baseline separation at retention windows of approximately 4.7 minutes and 6.3 minutes, respectively. Validation of the developed method performed in accordance with International Council for Harmonisation Q2(R1) regulatory guidelines confirm robust linearity across working concentration boundaries of 10- 50 μg/mL for furosemide and 25-125 μg/mL for spironolactone. Mean analytical recoveries range from 99.08%- 100.21% showing exceptional system accuracy devoid of chemical interference from common diagnostic tablet excipients. Forced degradation studies conducted under hydrolytic, oxidative, photolytic, and thermal stressors verify the stability-indicating capacity of the assay, as all generated degraded products resolve from the intact active therapeutic molecules. The validated method is highly reproducible and suitable for implementation within routine industrial quality control protocols and long-term shelf-life stability evaluations.