Merck & Company Incorporated failed to warn doctors about the risks of its withdrawn pain medicine Vioxx, a federal jury in New Orleans determined on Thursday. The jury said adequate compensation would be $50 million to retired Federal Bureau of Investigation agent Gerald Barnett, who suffered a heart attack in 2002 after taking Vioxx for 31 months for pain caused by a car accident. Merck “knowingly misrepresented or failed to disclose” information about the drug to Barnett's doctors, the jury said. The same jury will deliberate later in the day on possible punitive damages. The panel ruled against Merck on two of three central questions. It said the pharmaceutical giant was negligent in failing to adequately warn doctors about the risks of Vioxx and that such negligence was a legal cause of injury. Merck has now lost four cases and won five in its defense of Vioxx. Barnett's lawsuit is among more than 16,000 Vioxx-related lawsuits against Merck in U.S. state and federal courts. Shares of Merck fell 63 cents, or 1.5 percent, to $40.56 on the New York Stock Exchange in late morning trade.