Spironolactone-induced changes in digoxin kinetics.

Plasma clearance, volumes of distribution, and renal and extrarenal clearances of digoxin were calculated from plasma digoxin concentrations and urinary excretion of digoxin after intravenous injection of digoxin in 8 subjects. The investigation was repeated in the same subjects during long-term treatment with spironolactone. Increased plasma concentration of digoxin was detected during spironolactone treatment.