Methylprednisolone EP Impurity A Catalogue G112641 CAS 91523-05-6 M.W 372.45 M.F C22H28O5 Specifications FAQs (6S,8S,9S,10R,13S,14S,17R)-17-hydroxy-17-(2-hydroxyacetyl)-6,10,13-trimethyl-7,8,9,10,12,13,14,15,16,17-decahydro-3H-cyclopenta[a]phenanthrene-3,11(6H)-dione