Two separate Phase III successes in pulmonary hypertension could put pressure on Glaxo Wellcome's Flolan epoprostenol prostacyclin, the only marketed drug for the disorder. Actelion Ltd. last week released significant Phase III data on bosentan, following on last month's announcement by United Therapeutics Inc. that its Phase III trial of Uniprost was statistically significant. Given decent efficacy data, either new compound would be preferable to Flolan, given Flolan's short half-life of six minutes and delivery via catheter.

Pulmonary hypertension results from lowered prostacyclin, a potent vasodilator, and elevated endothelin, a vasoconstrictor. Patients