Overview PHIRST-1: Tadalafil in the Treatment of Pulmonary Arterial Hypertension Status: Completed Trial end date: 2007-08-01 Target enrollment: Participant gender: Summary The purpose of this study is to evaluate the safety and effectiveness of tadalafil for the treatment of pulmonary arterial hypertension. Phase: Phase 3 Details Lead Sponsor: Eli Lilly and CompanyCollaborator: ICOS CorporationTreatments: Tadalafil