Kermit B. Gosnell — the West Philadelphia physician awaiting trial on murder charges for providing illegal late-term abortions resulting in the deaths of a woman and seven newborns — pleaded not guilty Thursday to federal charges that he operated a "pill mill," selling prescriptions for more than one million pills of powerful narcotics.

Gosnell, 71, appeared before U.S. Magistrate Judge Elizabeth T. Hey to be arraigned on an amended version of the December indictment charging him and three employees with selling prescriptions for the narcotic painkiller oxycodone and the generic version of the antianxiety drug Xanax. Gosnell, who appeared healthy after recently undergoing the implantation of a heart pacemaker while in federal custody, said nothing else during the brief appearance at the federal courthouse in Center City.

Gosnell and three workers at his Women's Medical Society Clinic at 3801 Lancaster Ave. were originally charged by a federal grand jury in December with operating the pill mill from 2008 to January 2010. The alleged scheme netted Gosnell at least $200,000, prosecutors said.

Four other former Gosnell workers were charged separately in the drug case. Three of the four have pleaded guilty and are expected to testify for the government when the case goes to trial.

That could be some time, however. U.S. District Judge Cynthia M. Rufe has marked the trial "complex," and a trial date has not been scheduled.

When federal and state investigators raided Gosnell's clinic in February 2010, it was part of the probe into the sale of prescription pharmaceuticals. Once inside, however, authorities were confronted by evidence that Gosnell's West Philadelphia clinic was performing illegal late-term abortions for poor women.

The clinic and Gosnell became the subject of an investigation by a Philadelphia grand jury, and in January 2011 Gosnell and nine employees were charged by the District Attorney's Office.

Gosnell faces the most serious charges, including third-degree murder in the 2009 death of a Virginia woman undergoing an abortion and seven counts of first-degree murder in the deaths of seven infants who were allegedly born live and viable but then killed by Gosnell. He faces the death penalty if a jury finds him guilty of the first-degree murder charges.

The trial has been set for March 14 before Common Pleas Court Judge Jeffrey P. Minehart.

Contact Joseph A. Slobodzian at 215-854-2985 or jslobodzian@phillynews.com, or follow on Twitter @JoeSlobo.