 NXN-188 can bind to both 5-HT1D and 5-HT1B receptors with potency similar to sumatriptan; it also selectively binds to nNOS with a level of nNOS inhibition similar to L-NMMA. NXN-188 is devoid of any relevant eNOS inhibition in in vitro cloned human enzyme assays or ex vivo in human coronary arteries and is expected to be effective in treating migraine by inhibition of the nNOS enzyme without vasoconstrictive effects associated with non-selective compounds such as L-NMMA. 