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

Medco Stockholder Suits Dismissed: A federal judge dismissed two shareholder lawsuits against Medco Research Inc. in Los Angeles, clearing company officials of allegations that they issued false and misleading statements about the potential sale of Medco last year. U.S. District Court Judge David Kenyon threw out the cases, which had contended that Medco, a developer of drugs aimed at treating heart diseases, had violated securities laws. The suits were filed in August after a drop in the company’s stock. A third shareholder action filed this month is pending against Medco, and the Securities and Exchange Commission has launched an informal inquiry into the company’s affairs. A Medco spokesman said the firm intends to “actively defend itself against the allegations” in the remaining suit. (Case Nos. 90-4602, 90-4689. Ruling issued Jan. 28)