Spironolactone EP Impurity A

: Δ20-spironolactone; S-[(2′R)-3,5′-dioxo-5′H-spiro[androst-4-ene-17,2′-furan]-7α-yl] ethanethioate; (7α,17α)-7-(Acetylthio)-17-hydroxy-3-oxo-pregna-4,20-diene-21-carboxylic Acid γ-Lactone; Spiro[17H-cyclopenta[a]phenanthrene-17,2'(5'H)-furan] Pregna-4,20-diene-21-carboxylic Acid