Synonyms: Spiro[17H-dicyclopropa[1,2:6,7]cyclopenta[a]phenanthrene-17,2'(3'H)-furan]-3(1H)-one,21,21-difluoro-2,4',5',6,7,8,9,10,11,12,13,14,15,16,20,21-hexadecahydro-10,13-dimethyl-,[1S-(1a,2a,6a,7a,8a,9b,10a,13a,14b,17a)]-;Spiro[17H-dicyclopropa[1,2:6,7]cyclopenta[a]phenanthrene-17,2'(3'H)-furan]-3(1bH)-one, 6a,6a-difluoro-1a,2b,4',5',6b,6a,7b,8b,9a,10,11,12,13,14a,15,16-hexadecahydro-10b,13b-dimethyl-, (17R)- (8CI); 2',3'a-Tetrahydrofuran-2'-spiro-17-(6,7a-difluoromethylene)-1,2a-methylene-4-androsten-3-one; 6a,7a-(Difluoromethylene)-1a,2a-methylene-20-spirox-4-en-3-one; 6a,7a-Difluoromethylene-4',5'-dihydro-1a,2a-methylene-(17R)-spiro-[androst-4-ene-17,2'(3'H)-furan]-3-one; 6a,7a-Difluoromethylene-4',5'-dihydro-1a,2a-methylene-(17R)-spiro[androst-4-ene-17,2'(3H)-furan]-3-one;MK 316