Inspire Pharmaceuticals Inc. tumbled59 percent in Nasdaq trading after the company said its cysticfibrosis drug failed to benefit patients in the final stages oftesting, undermining earlier results.

Inspire fell $4.93 to $3.47 at 4 p.m. New York time inNasdaq Stock Market composite trading. it was the biggestsingle-day decline for the Durham, North Carolina-based companysince January 2002.

Cystic fibrosis is an inherited disease that leads tobuildup of mucus in the lungs and pancreas, causing infections.Patients taking Inspire’s drug, called denufosol, for 48 weeksshowed no improvement in a measure of breathing called forcedexpiratory volume, the company said in a statement. The resultscontradict a mid-stage study in June 2008 that sparked a single-day gain of 35 percent for Inspire shares.

“Results were both disappointing and unexpected,” saidAdrian Adams, chief executive officer of Inspire, in aconference call with investors. “We plan to provide a moredetailed corporate update on plans going forward by the middleof February.”

The 466-patient trial also failed to achieve improvement insecondary goals, according to the statement. Analysis ofsubgroups of patients with varying characteristics failed toidentify any population whose symptoms improved after taking thedrug.

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