fell more than 36% Monday after the company announced disappointing tests results for a drug designed to treat pain caused by peripheral vascular disease.
A recently completed U.S. trial of Beraprost failed to confirm the efficacy found in an earlier European trial, the company said. United Therapeutics was expected to release the Beraprost results at the upcoming scientific meeting of the American Heart Association, starting Nov. 11.
United Therapeutics dropped $5.97, or 36%, to $10.39 in trading Monday morning.
Beraprost was being developed initially to treat patients suffering from intermittent claudication, or pain that results from a narrowing of arteries in the arms and legs. Based on the failed U.S. test, the company said it will stop developing Beraprost for this indication, but will go ahead with efforts to investigate use in pulmonary arterial hypertension.
"We are completely surprised by the discrepancy between the results achieved in this study and the significant results achieved by the European study," said Michael Wade, United Therapeutics' associate director of research and development.
United Therapeutics is awaiting a Food and Drug Administration decision on another drug, Remodulin, for the treatment of pulmonary arterial hypertension. Company executives have said they expect to receive an approvable letter from the FDA in the next week.