In a news conference on Thursday, Montgomery County District Attorney Risa Vetri Ferman announced the arrest of 76-year-old Dr. Richard Ruth of Souderton.
Authorities say he wrote nearly 1,800 prescriptions for oxycodone over the course of a year, distributing some 240,000 pills.
Ferman said the practice targeted young adults in their 20s.
"Patients would come in and they would get minimal medical exams, really no medical treatment to speak of," Ferman said. "All they needed to bring was cash and they would get a prescription for one of the most powerful narcotics known to man."
Ferman went on to say that while police were executing the search warrant, patients were still coming in to the office - some stumbling - to fill their prescriptions.
"They had no idea what was going on," Ferman said. "They just needed their drugs."
Ruth is charged with prescription fraud, identity theft and insurance fraud.
Ferman pointed out that Ruth had been banned from writing prescriptions in 2005 for the same kind of activity, but got his license back in 2009.
Ruth's son, 43-year-old Michael Ruth, was also arrested on conspiracy and related charges.