Two multibillion-dollar pharmaceutical companies faced off in federal court in Pittsburgh yesterday in a battle over the right to sell one of the world's leading cardiovascular medications.

	RELATED STORY Pfizer cutting U.S. sales force by 20 percent

The showdown between New York-based Pfizer Inc., the world's largest drug company, and Canonsburg-based Mylan Laboratories Inc., the region's biggest drug maker, dates to a lawsuit filed four years ago over Norvasc, a drug Pfizer has been selling for 14 years.

In the lawsuit, filed in 2002, Pfizer alleges Mylan infringed on its patent for the popular blood pressure medication.

Two months earlier, Mylan had filed an application with the U.S. Food and Drug Administration to get approval to sell a generic version of Norvasc, which earlier this year was ranked as the fourth best-selling drug in the world.

The patent for the medication, which Pfizer initially received in 1987 and recently was extended six months, expires in September, so whoever wins the case will only win the right to sell the drug for less than a year.

It's a short time frame, but in terms of financial return, the implications are huge. In the first nine months of this year, Norvasc had worldwide sales of $3.54 billion -- or more than $390 million per month.

To put that in perspective, Mylan had total sales for all of its 160-plus products last fiscal year of $1.25 billion.

Pfizer's annual sales were $52 billion.

But Bryant Haskins, a spokesman for Pfizer, said there's more than money at stake.

"There's principle here," he said. "Patents are critical to our business, and we protect them. We take our intellectual property as our lifeblood.

"That's what provides us the capability to develop new, life-saving products going forward."

A bench trial on the matter began yesterday before U.S. District Judge Terrence F. McVerry. It is expected to last about seven days.

Mylan has admitted to infringing on Pfizer's patent, but claims the patent is invalid and unenforceable. That is what Mylan's lawyers will attempt to prove this week as they present their case.

The first witness called by the company yesterday was Dr. James I. Wells, a co-inventor of Norvasc.

He spent most of the day on the stand, and was called a hostile witness by Mylan.

Mylan attorney Steven M. Lieberman hounded Dr. Wells with questions, finally getting him to admit that the patent application submitted for Norvasc contained an incorrect formula.

"Is the patent wrong when it described what you tested?" Mr. Lieberman asked.

"Those numbers do not match up," Dr. Wells responded.

"I want to know is the patent wrong?" the lawyer asked again.

"In a way, yes," Dr. Wells answered.

He tried to explain that the patent application wasn't filed until years after he had completed his work on the project.

"It was three years later when I read both documents, and it made sense at the time," Dr. Wells said. "It's perfectly explainable. It's not very clever, but that's the facts."

Mylan, which has brought a handful of similar patent challenges in its 46-year history, earned a partial victory in October, when Judge McVerry threw out a separate patent infringement claim by Pfizer because the patent had expired July 31, making it moot.

Mylan won approval to make its generic version of Norvasc -- amlodipine besylate -- from the FDA in October 2005. The company, however, has not yet started marketing the drug, because if it loses the lawsuit, it could face substantial financial penalties.

Patrick Fitzgerald, a spokesman for Mylan, said he could not say what price his company would put on amlodipine besylate.

The 5-milligram version of Norvasc sells at www.drugstore.com for $45.99 for 30 tablets.

"One product isn't necessarily going to be the key for a generic drug company," Mr. Fitzgerald said. "We're likely to face significant competition for that product."

Mylan has exclusive rights to the generic version of Norvasc for six months because it was the first company to file on all strengths of the medication.

"Sometimes, the sheer brand success can be misleading," he said.

Pfizer has already won two similar patent infringement cases involving Norvasc this year: A federal judge in Illinois decided against Apotex Inc. in January. Then, a federal judge in North Carolina decided against Synthon Laboratories in August. Both companies have appealed those decisions.