Biotechnology Switzerland's Actelion yesterday saw its shares plunge 16.2% to 45.90 Swiss francs, its lowest level for four years, after the company announced the initial results of BUILD-3, a clinical study evaluating the safety and efficacy of its lead product bosentan (sold as Tracleer) in patients suffering from idiopathic pulmonary fibrosis (IPF). While there was a consistent trend in favor of bosentan, the primary endpoint, reduction in morbidity/mortality, was not met (p=0.21). However, the company noted, the well characterized safety profile of bosentan was confirmed. 2 March 2010