Methylprednisolone EP Impurity C Catalogue G112643 CAS 61919-52-6 M.W 314.42 M.F C20H26O3 Specifications FAQs (6S,8S,9S,10R,11S,13S,14S)-11-hydroxy-6,10,13-trimethyl-7,8,9,10,11,12,13,14,15,16-decahydro-3H-cyclopenta[a]phenanthrene-3,17(6H)-dione