BYK204165 is a potent and selective PARP1 inhibitor. BYK204165 inhibits cell-free recombinant human PARP-1 (hPARP-1) with a pIC₅₀ of 7.35 (pK_i=7.05), and murine PARP-2 (mPARP-2) with a pIC₅₀ of 5.38, respectively. BYK204165 displays 100-fold selectivity for PARP-1^[1]. IC50 & Target: pIC50: 7.35 (hPARP-1), 5.38 (mPARP-2)^[1] In Vitro: In kinetic experiments with human PARP-1, BYK204165 exhibits potent and competitive inhibition of enzyme activity, yielding a pK_i value of 7.05^[1].
BYK204165 exhibits low potency of PARP inhibition in C4I cells (pIC₅₀ of 5.75)^[1]. In Vivo: BYK204165 is not investigated in vivo because of its short half-time (t_1/2) of 23 min measured at rat microsomes in vitro^[1].