What is the efficacy of treprostinil for the treatment of pulmonary arterial hypertension (PAH)?

Updated: Apr 25, 2018
  • Author: Kristin E Schwab, MD; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Answer

Treprostinil is a stable prostacyclin analogue that can be administered parenterally (Remodulin), as a continuous subcutaneous infusion delivered by a minipump (Remodulin), as an inhaled therapy (Tyvaso), or as an oral tablet (Orenitram). Treprostinil elicits direct vasodilation of pulmonary and systemic arterial vessels and inhibits platelet aggregation. Vasodilation reduces right and left ventricular afterload and increases cardiac output and stroke volume. A multicentric randomized trial evaluating treprostinil versus placebo over 12 weeks in 470 patients documented that patients with PAH had increases in 6-minute walk distances (6MWDs), dyspnea, and hemodynamic measurements. [40] A subsequent multicenter retrospective study of 122 patients with PAH or chronic thromboembolic pulmonary hypertension (CTEPH) treated over a 3-year period demonstrated significant improvement in long-term survival rates. [41] A randomized controlled trial by McLaughlin et al demonstrated the addition of inhaled treprostinil improved exercise capacity and quality of life among 212 patients with PAH, who remained symptomatic despite therapy with bosentan or sildenafil. [42] In December 2013, the FDA approved treprostinil extended-release tablets (Orenitram) for pulmonary arterial hypertension. The primary efficacy study, FREEDOM-M, demonstrated patients taking titrated treprostinil orally twice daily improved median 6MWD by +23 meters (P = .013) compared with placebo. [43] Two other phase 3 studies (FREEDOM-C and FREEDOM-C2) did not demonstrate a benefit in exercise with median 6MWD at week 16 (11 meters [P = .072] and 10 meters [P = .089], respectively). [44, 45] Adverse effects depend on the mode of administration (ie, infusion site pain is the most common adverse effect with the subcutaneous form), but are otherwise similar to epoprostenol. Compared with epoprostenol, treprostinil has gained more widespread use, largely because of its longer half-life and thus better safety profile.


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