LAS VEGAS (AP) – A doctor and his wife were arrested Thursday on charges their medical practice injected patients with an unapproved botulism toxin instead of the anti-wrinkle drug Botox, authorities said.

Dr. Stephen Lee Seldon, 52, and his wife, Deborah Martinez Seldon, 39, each pleaded not guilty in federal court in Las Vegas to 14 counts of mail fraud and one count of adulterating a drug held for sale, acting U.S. Attorney for Nevada Steven Myhre said.

Beginning in October 2003, Stephen Lee Seldon purchased the cheaper Botox alternative, known as botulinum toxin type A, without alerting patients at A New You Medical Aesthetics, his Las Vegas practice managed by his wife, according to an indictment unsealed Thursday.

The indictment said the couple purchased more than $86,000 of the drug by mail from Tucson, Ariz.-based Toxin Research International Inc., which labeled it for “Research purposes only, not for human use.”

Myhre said the Seldons falsified patient waivers to cover up the use of the unauthorized substance, and falsely advertised they were using Botox in magazine ads.

“The Seldons maintain they never injected patients with anything that was not approved by the FDA,” Deborah Seldon’s lawyer, Donn Ianuzi, said.

Stephen Seldon had not yet retained a lawyer.

If convicted, the Seldons face up to 20 years in prison and a $250,000 fine on each mail fraud count, and up to one year in prison and a $100,000 fine on the drug adulterating charge. They were released on a personal recognizance bond.

Myhre said the case against the Seldons grew out of an investigation of Toxin Research International and its principal owners, Chad Livdahl and Zahra Karim. In 2005, Livdahl and Karim were convicted of conspiracy and mail fraud in the U.S. District Court in the Southern District of Florida for selling almost $2 million of the Botox substitute to doctors.