RPL-554 (Ensifentrine, LS-193855, RPL554) is a potent, orally available, dual PDE3/PDE4 inhibitor with IC50 of 0.4 nM and 1479 nM, respectively.
RPL-554 inhibits LPS-induced TNFα release from human monocytes with IC50 of 0.52 uM, and proliferation of human mononuclear cells to phytohemagglutinin (IC50=0.46 uM).
RPL-554 significantly inhibits eosinophil recruitment following antigen challenge in ovalbumin-sensitized guinea pigs (10mg/kg).
