Determination of Spironolactone and Canrenone in Human Plasma by High-performance Liquid Chromatography with Mass Spectrometry Detection.

A new simple, sensitive and LC-MS/MS method for quantification of spironolactone and its metabolite, canrenone, in human plasma is proposed. The analytes were analysed on a C18 column at 48 0°C, by using a mobile phase of 58 % methanol, 42 % 10 mmol dm ammonim acetate in water and a flow rate of 1 mL/min. The detection of both analytes in plasma was performed as follows: ESI+, EIC (m/z 169;187;283;305) from m/z 341, after protein precipitation with methanol. Calibration curves were generated over the ranges 2.77-184.50 ng/mL for spironolactone and 2.69-179.20 ng/mL for canrenone by using a weighted (1/y) linear regression. The absolute values of within- and between-run precision and accuracy for both analytes ranged between 3.1 and 13.9 %, and the mean recovery was 99.7 %. The analytes demonstrated good stability in various conditions. The validated method has been applied to a bioequivalence study of 50 mg spironolactone tablets on healthy volunteers. [ABSTRACT FROM AUTHOR]