Budesonide Impurity 09 Catalogue B501489 CAS 109423-03-2 M.W 446.53 M.F C25H34O7 Specifications FAQs (11β,16α)-11,21-Dihydroxy-16,17-[(2-hydroxybutylidene)bis(oxy)]pregna-1,4-diene-3,20-dione