Budesonide Impurity 07 Catalogue B501487 CAS 93861-51-9 M.W 446.53 M.F C25H34O7 Specifications FAQs [6β,11β,16α(S)]-16,17-[Butylidenebis(oxy)]-6,11,21-trihydroxy-pregna-1,4-diene-3,20-dione