Staggered Transition to Epoprostenol from Treprostinil in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is characterizedby increased pulmonary artery pressure, pulmonary vascular resistance, and vascular remodeling. The disease is progressive, with increasing pulmonary vascular pres-sure and pathology associated with increased right heart failure, dyspnea, chest pain, fatigue, syncope, and overall declining functional status. PAH has been subclassified into several categories including PAH associated with dis-orders of the respiratory system or chronic hypoxemia, pulmonary venous hypertension due to conditions such as connective tissue disease, toxins, or chronic thromboem-bolic disease. Idiopathic PAH (IPAH) is extremely rare, occurring in about 2 persons per million individuals per year, either sporadically or on a familial basis. When the disease is poorly managed, the mortality rate is substantial. A National Institutes of Health registry measuring the nat-ural history of PAH over a 5-year period yielded a one-year survival rate of 68 % (mean 2.8 y, overall 30%).1,2 Therapeutic options for treatment of PAH were limited until the emergence of prostacyclin analogs, endothelin re-ceptor antagonists, and other promising drug therapies. The 2 prostacyclin analogs that have been extensively in-vestigated and approved for treatment of PAH are epo-prostenol and treprostinil. The second class approved for the treatment of PAH is the endothelin receptor antago-nists; bosentan is currently the only Food and Drug Ad-ministration–approved agent.3 Epoprostenol (prostacyclin), a naturally occurring pro-staglandin, is a potent vasodilator, as well as inhibitor o