London, England (AHN)- Pharmecutical giant, Biovail has lost the patent infringement case for its hit antidepressant drug Wellbutrin XL. The ruling will allow generic copies of the drug to enter the market.

The U.S. court ruling caught the company unaware and resulted in in their stock's market value droppinga quarter.

An industry analyst claims that the news will now decrease any possibility of Biovail negotiating for a settlement with four generic drug companies to delay competition.

In a statement revealed by the company it said it's reevaluating its financial forecast for 2006 of revenue between $900-million and $1.07-billion and a share profit of $2.30 to $2.40.

"That's the most negative thing Biovail said in its press release," one unnamed analyst told Globe And Mail.

"It kind of implies that a generic could show up sooner than later," he said.

The drug is sold for Biovail by Britain's GlaxoSmithKline. Last year, 40 percent of the company's earnings came from Wellbutrin XL. Which translates to $1.2 billion in revenues.

"At this point, it appears that the likelihood of a generic Wellbutrin XL entering the market earlier than our current first-half 2008 [forecast] is substantially increased," UBS Securities analyst Jeff Elliott said in a new report.

He says a probable generic launch in the first half of 2007 could delete the $160-million of Biovail profit or $1 to $1.20 a share next year.