Potent inhibitor of MEK1/2. Inhibits isolated enzyme at a concentration of 8 nM and inhibits MEK activity in synovial fibroblasts at concentrations of 30 - 100 nM. Highly selective for MEK; IC50 values are > 1, > 4, > 4 and > 10 μM for ERK, c-Src, cdks and PI 3-kinase γ respectively. Antihyperalgesic; blocks static allodynia in the streptozocin model of neuropathic pain following i.t. administration. Purity 98%. MW (observed): 476.23