LOS ANGELES --  A Sunset Strip dermatologist with a celebrity clientele pleaded not    guilty today in a Los Angeles courtroom to federal charges stemming from allegations that he injected patients with a fake Botox that can cause dangerous side-effects.

Dr. David Cary Hansen, 52, was indicted Dec. 17 on 10 federal counts of mail fraud and misbranding a drug and released the next day on $50,000 bond.

Prosecutors allege Hansen charged patients for costly Federal Drug Administration-approved Botox injections but gave them a less-expensive, unapproved form of botulinum toxin type A.

Botox is marketed and sold by Allergan Inc. for use in reducing facial wrinkles.

"These are overblown, exaggerated charges," Mark J. Werksman, Hansen's attorney, said outside court today. "He never intentionally ordered or used any misbranded or unapproved substances on any patient ever.

In December 2003 and July 2004, Hansen is alleged to have purchased at least a dozen vials of the unapproved form of botulinum toxin type A -- marked for research purposes only and not for human use -- from a company in Arizona.

High doses of botulinum toxin type A can cause respiratory paralysis, according to the indictment.

Hansen is accused of injecting patients with the non-approved substance at his Sunset Strip clinic in West Hollywood while advising them that he was injecting them with Botox, according to court documents.

Hansen charged $300 for treatment of one facial area, $450 for two facial areas and up from there, Assistant U.S. Attorney Janet C. Hudson said.

The cosmetic surgeon's clients included a number of Hollywood celebrities, but Hudson declined to give their names to protect their privacy.

According to the prosecution, the link to Hansen eventually came about after a South Florida osteopath with a suspended medical license injected himself and three others in 2004 with improperly diluted amounts of the raw toxin purchased from a Northern California laboratory.

All four were hospitalized in critical condition with botulism, after having received catastrophic amounts of the toxin, Hudson said.

A federal investigation found that the same Northern California laboratory also sold botulinum toxin type A in a formulation designed to imitate Allergan's Botox to a company in Tucson, Ariz., called Toxin Research International.

A search of business records in Tucson found Hansen's name on a list of some 200 doctors who allegedly purchased the fake, hazardous Botox imitation from the company, Hudson said.

U.S. Magistrate Judge Frederick F. Mumm today set a Feb. 2 trial-setting date before U.S. District Judge John F. Walter.

If convicted of all counts, Hansen faces a maximum sentence of 60 years in federal prison and fines of $600,000, officials said.