ML-204 selectively blocks transient receptor potential canonical 4 (TRPC4) channels (IC50s = 0.96 and 2.6 μM in fluorescent and electrophysiological assays, respectively). It exhibits 19-fold selectivity against TRPC6 and 9-fold selectivity against TRPC5 and does not affect TRPV1, TRPV3, TRPA1, or TRPM8 channels at concentrations up to 22 μM.