The application discloses novel polymorphic crystalline forms of 2-[4-Bromo-3-(3-chloro- 5-cyano-phenoxy)-2-fluoro-phenyl]-N-(2-chloro-4-propionylsulfamoyl-phenyl)-acetamide, sodium salt (Ib) with improved stability and physical properties which facilitate manufacturing, handling and formulating for treatment or prophylaxis of HIV mediated diseases, AIDS or ARC, in monotherapy or in combination therapy.
