“4 Kd for progesterone was 3.2 X 10(-9)M. Ki (the inhibition constant for canrenone with respect to progesterone binding) was 300 X 10(-9)M. Reports in the literature suggest that, following spironolactone administration, canrenone may rise to concentrations sufficiently high to inhibit progesterone binding.”
“There was marked cooperativity in progesterone binding at high canrenone and low progesterone concentrations.”