WASHINGTON (AP) — A Democratic senator is seeking marketing information, sales records and studies from manufacturers of the top-selling opioid products in the United States to determine whether drugmakers have contributed to an overuse of the pain killers. Some of the records she is asking for from the five companies include the sales rep expenses for entertaining physicians, payments made to health care advocacy groups, as well as marketing and business plans. More than 52,000 people died of a drug overdose in 2015, and roughly two-thirds of them had used prescription opioids like OxyContin or Vicodin or illegal drugs like heroin, according to the Centers for Disease Control and Prevention.