A new medical study has concluded that the drug giant Merck should have pulled its Vioxx painkiller drug from the market four years ago when researchers first revealed that the drug raised the risk of heart attacks. Merck didn’t pull the drug until 5 weeks ago. The US Food and Drug Administration recently published a study estimating that Vioxx could have caused about 28,000 heart attacks or deaths since it was approved in 1999.