Intravenous epoprostenol improves exercise capacity and survival in patients 
with pulmonary arterial hypertension (PAH); however, chemical instability and a 
short half-life have caused limitations in its use. The chemically stable 
prostacyclin analogue treprostinil has a longer half-life, and improves 
hemodynamics and signs/symptoms of PAH. This study investigated the feasibility 
of transitioning patients with PAH from intravenous epoprostenol to intravenous 
treprostinil using a rapid switch protocol. Twelve PAH patients were enrolled in 
a 12 week prospective open label study. Patients were switched from intravenous 
epoprostenol to intravenous treprostinil (1:1 ng/kg/min) by a direct switch of 
the medication reservoir from epoprostenol to treprostinil. The dose of 
treprostinil was adjusted throughout the study to achieve a 2-fold increase of 
treprostinil compared with the baseline epoprostenol dose. Rapid transition to 
treprostinil was achieved without serious adverse events and, baseline clinical 
status was maintained over 12 weeks. The mean baseline epoprostenol dose was 28 
+/- 14 ng/kg/min. At week 12, the mean treprostinil dose was 62 +/- 30 
ng/kg/min. All patients reported less prostacyclin-related side effects with 
treprostinil and remained on treprostinil after study completion. Selected 
patients with PAH can be safely transitioned from intravenous epoprostenol to 
intravenous treprostinil using a rapid switch protocol.