Simultaneous kinetic spectrophotometric determination of spironolactone and canrenone in urine using partial least-squares regression

Successive ratio subtraction as a novel manipulation of ratio spectra for quantitative determination of a mixture of furosemide, spironolactone and canrenone

Furosemide and spironolactone are commonly prescribed antihypertensive drugs. Canrenone is the main degradation product and main metabolite of spironolactone. Ratio subtraction and extended ratio subtraction spectrophotometric methods were previously applied for quantitation of only binary mixtures. An extension of the above mentioned methods; successive ratio subtraction, is introduced in the presented work for quantitative determination of ternary mixtures exemplified by furosemide, spironolactone and canrenone. Manipulating the ratio spectra of the ternary mixture allowed their determination at 273.6nm, 285nm and 240nm and in the concentration ranges of (2-16μgmL^-1), (4-32μgmL^-1) and (1-18μgmL^-1) for furosemide, spironolactone and canrenone, respectively. Method specificity was ensured by the application to laboratory prepared mixtures. The introduced method was ensured to be accurate and precise. Validation of the developed method was done with respect to ICH guidelines and its validity was further ensured by the application to the pharmaceutical formulation. Statistical comparison between the obtained results and those obtained from the reported HPLC method was achieved concerning student's t-test and F ratio test where no significant difference was observed.

Simultaneous identification and quantification of canrenone and 11-α-hydroxy-canrenone by LC-MS and HPLC-UVD

A procedure for simultaneous identification and quantification of canrenone and its biotransformed product 11-α-hydroxy-canrenone by high-performance liquid chromatography with ultraviolet detector (HPLC-UVD) and mass spectrometry (LC-MS) methods was proposed. The optimal determination variables on the HPLC-UVD or LC-MS coupled with a ZORBAX Eclipse XDB-C18 column (150 mm × 4.6 mm, 5 μm) were set as follows: detection wavelength of 280 nm, mobile phase of water and methanol gradient elution, temperature for the chromatographic column of 30°C, flow rate of mobile phase of 0.8 mL/min, sample injection volume of 5 μL, and elution time of 40 min. The MS conditions were set as follows: the flow rate of sheath gas, aux gas, and sweep gas were kept at 35 arb, 5 arb, and 0 arb, respectively. The temperature of capillary was held at 300°C, and capillary voltage was set at 30.00 V. Tube lens were performed at 100.00 V. The proposed method was validated by linearity (r² ≥ 0.9910), average recovery (94.93%, RSD1.21%), precision (RSD ≤ 1.31%), limit of detection, and limit of quantification (LOD 0.1~0.12 mg/L, LOQ 0.5~0.67 mg/L), which proved to be affordable for simultaneously determining canrenone and its bio-transformed product 11-α-hydroxy-canrenone.