Inhaled treprostinil and pulmonary arterial hypertension.

Multiple conditions result in development of pulmonary hypertension. Pulmonary arterial hypertension (PAH) is the subclassification of pulmonary hypertension, in which known or unknown underlying conditions lead to similar intrinsic alterations in the pulmonary vasculature. PAH is a progressive condition characterized by restricted blood flow through the pulmonary circulation leading to poor survival in the absence of effective therapy. Over the last two decades, new therapeutic agents have substantially improved the course and prognosis for PAH patients. Three available classes of drugs, ie, prostacyclins, endothelin receptor antagonists, and phosphodiesterase-5 inhibitors provide multiple options for treatment of PAH. Endothelin receptor antagonists and phosphodiesterase-5 inhibitors are administered orally, whereas prostacyclin therapies are delivered by continuous intravenous or subcutaneous infusion, or as aerosols by nebulization. Because of the risks and inconveniences associated with administration, prostacyclins are typically reserved for patients with more advanced disease or progression despite oral therapy. Inhaled administration may be a safer and easier route for prostacyclin administration. Treprostinil is a prostacyclin analog that has been demonstrated to be effective when administered by continuous subcutaneous or intravenous infusion, and more recently by nebulization.