AM-0902 is a potent, selective antagonist of TRPA1 in vivo. AM-0902 has moderate terminal elimination half-life (t1/2=0.6 h and 2.8 h for rat (0.5 mg/kg, iv), rat (30 mg/kg, oral)). A dose-dependent reduction of allyl isothiocyanate (AITC)-induced flinching is observed for AM-0902, with a significant reduction in flinching observed postdosing of 10 and 30 mg/kg. The unbound plasma concentrations (Cu) at 1 h for the 1, 3, 10, and 30 mg/kg doses are 0.051±0.024 (n=8), 0.19±0.11 (n=8), 0.58±0.35 (n=8), and 2.2±0.40 (n=8) μM, covering the in vitro rat TRPA1 45Ca2+ IC50 at 0.72, 2.7, 8.2, and 30.3 fold, respectively. A good exposure-response relationship is observed in this target coverage model. An unbound in vivo IC50 of 0.35 μM, which is in good agreement with the in vitro rat TRPA1 45Ca2+ IC50, and unbound in vivo IC90 of 1.7 μM are determined. It is noteworthy that at a dose of 30 mg/kg, AM-0902 engages TRPA1 at concentrations that exceed the in vivo IC90, making it a useful tool for exploration of in vivo models of acute pain[1].
