3-((7R,8R,10S,13S,14S,17R)-17-hydroxy-7-(methoxycarbonyl)-10,13-dimethyl-3-oxo-2,3,6,7,8,10,12,13,14,15,16,17-dodecahydro-1H-cyclopenta[a]phenanthren-17-yl)propanoic acid, sodium salt