ME-0328 is a potent and selective PARP-3 inhibitor (IC₅₀ = 0.89 µM). ME-0328 inhibits PARP-1, PARP-2 and other ARDTs (ADP ribosyltransferases) at much higher concentrations (IC₅₀ = 6.3, 10.8 and >30 µM, respectively).