It is well established that the endothelin, nitric oxide and prostacyclin 
pathways play an important role in the development of pulmonary arterial 
hypertension (PAH). Indeed, the therapeutic options currently available for the 
management of PAH all act on one of these mechanistic pathways. However, this is 
an exciting time for both clinicians and scientists, as increased understanding 
of the mechanisms involved in the pathogenesis and progression of PAH has 
resulted in the development of a number of novel therapeutic options. This 
article highlights how the introduction of new compounds such as macitentan, 
riociguat and selexipag, which act on the endothelin, nitric oxide and 
prostacyclin pathways, respectively, have the potential to further improve the 
prognosis for patients with PAH.