The safety of fasudil in terms of the systemic hemodynamics of patients with severe PAH, as well as its long-term efficacy, should be further investigated. As fasudil is short acting and needs continuous infusion, a long-active oral or inhaled form of Rho-kinase inhibitor is desirable. An oral form of fasudil has been developed and its efficacy and adequate safety profile for the treatment of stable effort angina in a multicenter phase II study has been reported.32 In the near future, it will be available for clinical use, providing a new class of drugs for PAH.