Updated from 9:25 a.m. EDT

Wyeth ( WYE) shares fell Wednesday after a $1 billion Texas jury award against drugmaker late Tuesday.

The Madison, N.J.-based company said it would appeal the decision, which found the company responsible for the death of a woman who took one of its diet drugs.

Cynthia Cappel-Coffey, 41, died last year of primary pulmonary hypertension, four years after she took the diet drug Pondimin. Pondimin is part of the drug mix known as fen-phen, a combination that used phentermine with another Wyeth drug called Redux.

The combination was found to affect users' health, causing damage to the heart and lungs, according to the Majority Counsel, which represents the estimated 100,000 claimants in the class-action suit. About 6 million Americans used fen-phen, it said.

The suit by Cappel-Coffey's estate, heard in Beaumont, Texas, is one of a small number of cases not covered by the class action legislation.

A lawyer for Wyeth said the verdict has a good chance of being appealed, because of a number of "significant legal errors."

"There is absolutely no basis in the record for the amounts awarded," said Bill Sims. "While we sympathize with the Coffey family's loss, the verdict was contrary to evidence presented and the judgment far exceeds Texas' own statutory cap on punitive damages."

Sims said Cappel-Coffee was morbidly obese and had a family medical history of heart trouble. He said she did not develop PPH symptoms until four years after she'd stopped taking the Wyeth drug.

Wyeth shares were off 48 cents, or 1.2%, to $38.79.