ST. LOUIS • A California man admitted in federal court here Tuesday that he was a supplier of unapproved foreign chemotherapy drugs for U.S. patients in a case that has put dozens of doctors nationwide under scrutiny.

His voice breaking, James R. Newcomb, 61, of La Jolla, Calif., pleaded guilty to one felony count of conspiring to distribute adulterated prescription drugs. Newcomb owned and ran Ban Dune Marketing Inc., which distributed unapproved prescription medication from Jan. 1, 2008, to May 18, 2011, according to his plea.

"Mr. Newcomb very much regrets the situation he finds himself in," his attorney, Jim Martin, said later. There was no evidence that he ever wanted to harm anyone, Martin said, "and we don't believe that harm did come to anybody."

The company sent ads to doctors offering big discounts — an average of 40 percent — on expensive drugs while requesting that the doctors keep the price list "confidential."

In the fall of 2010, Newcomb and others began distributing chemotherapy drugs that had specific storage and handling requirements, but they failed to ensure that those needs were met, officials said.

Newcomb made roughly $179,000 from some of the prescription drug sales and admitted sending at least two shipments to a Missouri doctor, including one that arrived with a ruptured cold pack that turned it into a "gooey mess," officials said.

His indictment suggests that he considered —then rejected — including a thermometer that would track the temperature during the entire shipping period, saying he was afraid of opening a "Pandora's Box" and being forced to make refunds if doctors found the proper temperature was not maintained.

At sentencing May 25, Newcomb could face more than three years in prison, although his lawyer will argue for less time. Newcomb also will forfeit $1.4 million and a Land Rover seized during the investigation, prosecutors said.

He paid a $5,000 fine to California in February of 2008 because another business he owned was wholesaling prescription drugs without a state license.

Federal court documents here say that as many as 60 doctors bought unapproved chemotherapy drugs. Martin declined to comment when asked how many doctors were Newcomb's clients.

Last week, a St. Louis-area doctor pleaded guilty in the case to a misdemeanor charge of introducing misbranded prescription drugs into interstate commerce. Dr. Abid Nisar, 60, who has offices in Florissant, East St. Louis and Granite City, admitted buying $352,504 worth of drugs from Newcomb and co-defendant Sandra L. Behe, 44, also of La Jolla. Behe is also scheduled to plead guilty, her lawyer said last week.

Dr. Isabella Martire, 53, an oncologist in Laurel, Md., pleaded guilty in federal court in Maryland in August to the same charge as Nisar. She admitted buying almost $200,000 worth of unapproved, foreign prescription drugs from a United Kingdom drug wholesaler, saving $790,600, her plea says.