Pasteur Mérieux MSD has been renamed Aventis Pasteur MSD following the merger of Rhône-Poulenc SA and Hoechst AG. Pasteur Mérieux MSD is a joint venture between Pasteur Mérieux Connaught, part of Rhône-Polenc, and Merck & Co Inc. The change of name was effective in the United Kingdom from February 7.