Treprostinil (marketed under the trade names Remodulin for infusion) is a vasodilator that is used for the treatment of pulmonary arterial hypertension. Pulmonary arterial hypertension (PAH) is a disease in which blood pressure is abnormally high in the arteries between the heart and lungs. PAH is characterized by symptoms of shortness of breath during physical exertion. The condition can ultimately lead to heart failure. Treprostinil is a potent oral antiplatelet agent. The major pharmacologic actions of treprostinil are direct vasodilation of pulmonary and systemic arterial vascular beds and inhibition of platelet aggregation. In animals, the vasodilatory effects reduce right and left ventricular afterload and increase cardiac output and stroke volume. Other studies have shown that treprostinil causes a dose-related negative inotropic and lusitropic effect. No major effects on cardiac conduction have been observed. Treprostinil had high affinity for the Prostaglandin D2 receptor (DP1), Prostaglandin E2 receptor EP2 subtype (EP2) and Prostaglandin D2 receptor (IP) receptors (Ki 4.4, 3.6 and 32 nM, respectively), low affinity for EP1 and EP4 receptors and even lower affinity for EP3, Prostaglandin F (FP) and thromboxane (TP) receptors. Treprostinil has demonstrated a unique effect on PPAR gamma, a transcription factor important in vascular pathogenesis as a mediator of proliferation, inflammation and apoptosis. Through a complementary, yet cyclic AMP-independent pathway, treprostinil activates PPARs, another mechanism that contributes to the anti-growth benefits of the prostacyclin class.

Epoprostenol (marketed as FLOLAN, VELETRI) is a prostaglandin that is a powerful vasodilator and inhibits platelet aggregation. Epoprostenol (PGI2, PGX, prostacyclin), a metabolite of arachidonic acid, is a naturally occurring prostaglandin with potent vasodilatory activity and inhibitory activity of platelet aggregation. FLOLAN (epoprostenol sodium) for Injection is a sterile sodium salt formulated for intravenous (IV) administration. Epoprostenol has two major pharmacological actions: (1) direct vasodilation of pulmonary and systemic arterial vascular beds, and (2) inhibition of platelet aggregation. In animals, the vasodilatory effects reduce right and left ventricular afterload and increase cardiac output and stroke volume. The effect of epoprostenol on heart rate in animals varies with dose. At low doses, there is vagally mediated brudycardia, but at higher doses, epoprostenol causes reflex tachycardia in response to direct vasodilation and hypotension. No major effects on cardiac conduction have been observed. Additional pharmacologic effects of epoprostenol in animals include bronchodilation, inhibition of gastric acid secretion, and decreased gastric emptying. No available chemical assay is sufficiently sensitive and specific to assess the in vivo human pharmacokinetics of epoprostenol. FLOLAN is indicated for the long-term intravenous treatment of primary pulmonary hypertension and pulmonary hypertension associated with the scleroderma spectrum of disease in NYHA Class III and Class IV patients who do not respond adequately to conventional therapy.