Three doctors have been indicted on charges of selling $5 million worth of prescription drugs out of a South Philadelphia clinic that specialized on helping addicts.

Many who bought the medications at Alan Summers' clinic - called NASAPT, or the National Association for Substance Abuse-Prevention and Treatment - were drug dealers or addicts, according to federal prosecutors.

The federal grand jury indictment filed Wednesday in U.S. District Court in Philadelphia charges Summers, 78, of Ambler, and two of his employees, Azad Khan, 63, of Villanova, and Keyhosrow Parsia, 79, of Ridley Park, with distribution of controlled substances, conspiracy to distribute controlled substances, health-care fraud, and money laundering.

Prosecutors say the physicians sold prescriptions for Suboxone, a drug used to treat opiate addiction, and Klonopin, used to treat seizures and panic attacks, out of Summers' clinic at 2300 S. Broad St. between 2011 and 2014.

While they purported to operate a clinic providing substance abuse treatment to drug addicts, the doctors "sold prescriptions for controlled substances to drug dealers and drug addicts in exchange for cash payments and performed little or no medical or mental health treatment," the indictment says.

Nearly all of the 1,000 patients who passed through the clinic each month received the maximum doses of Suboxone and Klonopin, regardless of their health, the indictment says. The doctors did not perform the medical examinations required by law to legally prescribe the drugs, according to prosecutors.

An attorney for Summers said Summers was simply helping patients suffering from drug addiction. "The treatment was medically necessary and completely appropriate, and we hope to have an opportunity to show that when we get to court," Carrie Cinquanto said.

Khan, an internal medicine specialist, and Parsia, a psychiatrist, worked at the clinic in 2013 and 2014. They could not be reached Wednesday.

Summers and physicians at his clinic prescribed about 2.5 million Suboxone doses and 2.5 million doses of Klonopin, prosecutors say.

The indictment says Summers used part of the proceeds to pay the other two doctors to run the enterprise, Parsia received $153,193 and Khan $147,028, it says.