DSM Sues Sepracor And Tanabe

The Stamicarbon subsidiary of the Netherlands chemical group DSM haslaunched a legal action against Sepracor and Tanabe Seiyaku over a patent awarded to the two companies in November 1996. The patent covers the preparation of esters used to make the calcium antagonist diltiazem. A US Patent and Trademark Office board ruled last year that although the firm had the earliest patent application, filed in 1988, the application "did not disclose the best way of making and carrying out the invention."