A Blow to Efforts to Close In on Rivals.

Discusses how the recall of the arthritis drug Vioxx by Merck & Co. has come at a bad time for the pharmaceutical company. Way that this will affect their competition in the pharmaceutical industry; Suggestion that the withdrawal of the drug and concerns about Merck's ability to find successor drugs to its aging top sellers could push the company into a merger, Analysis of Merck's stocks; Lawsuits against the company by individuals who took Vioxx and suffered cardiovascular injuries; Plans for the company's future.