A summary of Southern California-related business litigation developments during the past week.

Shareholders Sue Drug Maker: Shareholders have filed a class-action suit against Medco Research Inc. and its officers, contending that it misled investors when it unsuccessfully attempted to find a new owner this year. The federal suit alleges that from March 12 to May 18, Medco’s stock dropped from an “artificially inflated” $20 a share to $13.75. The suit said the drop followed a stock selling spree by company officials, who had been asserting that several firms were interested in buying Medco. Although Oppenheimer & Co. was hired to help sell the company and a number of pharmaceutical firms were contacted about acquiring Medco, none expressed interest in it, the suit said. Meanwhile, it added, Medco officials artificially inflated the stock value by “misleading the market” into believing that Oppenheimer’s sales efforts would be successful. On May 17, Medco terminated its agreement with Oppenheimer. (Case No. 90-4689. Filed Aug. 30)