Pregna-1,4-diene-3,20-dione, 6,9-difluoro-11-hydroxy-16-methyl-21-((1-oxopentyl)oxy)-, (6alpha,11beta,16alpha)-, mixt. with 1-(2-(2,4-dichlorophenyl)-2-((2,6-dichlorophenyl)methoxy)ethyl)-1H-imidazole mononitrate