Progesterone receptor affinity

Steroid Receptors. Steroid receptors such as estrogen, progesterone, and androgen receptors are overexpressed in breast, ovarian, and prostate cancers. Estrogen and progesterone receptors are present in about 65% of human breast cancers. The presence or absence of these receptors in cases of breast carcinoma assists the determination of the therapeutic strategy (hormonal or chemical) that is likely to be effective. The successful Tc complex must cross the membrane lipid bilayer of the cell, and thus, the size and lipophilicity of the complex must be balanced with receptorbinding affinity. 

Epierenone is a potassium-sparing diuretic. It is similar to spironolactone as an aldosterone antagonist, but has less affinity for androgen and progesterone receptors and may therefore have fewer adverse effects (1). 

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