In the past 18 months, the U.S. Food and Drug Administration approved macitentan, riociguat, and treprostinil as oral agents for the treatment of pulmonary arterial hypertension (PAH); riociguat also became the first agent approved for the treatment of chronic thromboembolic pulmonary hypertension (CTEPH). These new agents are welcome additional therapeutic options for PAH and CTEPH. However, their use can be complicated by potential drug interactions, adverse effects, dosing complexity, and cost. Macitentan, the newest endothelin receptor antagonist, showed significant benefits in a long-term event-driven trial of morbidity and mortality. Dosed once daily and with minimal liver toxicity, it has potential drug interactions with potent CYP 3A4 inhibitors and inducers, and can decrease hemoglobin levels. Riociguat is approved for PAH and clinically inoperable CTEPH to improve exercise capacity and functional status. Riociguat requires dose titration beginning with 1 mg up to 2.5 mg three times a day, as tolerated, and should be used with caution in patients with underlying risk factors for systemic hypotension. Oral treprostinil, approved to improve exercise capacity in PAH, is associated with gastrointestinal side effects and headaches that are often dose limiting. Doses can begin with 0.125 mg or 0.25 mg twice a day with gradual increases on up to a weekly basis, as tolerated. Thrice daily dosing and administration with a meal can improve tolerance. These newer agents represent advances, but their specific roles in relation to pre-existing therapies are undergoing further evaluation. Therefore, close collaboration with clinicians at centers with therapeutic expertise is highly recommended to optimize patient outcomes.
Keywords: chronic thromboembolic pulmonary hypertension; macitentan; oral treprostinil; riociguat.