Active isomer of medetomidine, a potent, highly selective α2-adrenoceptor agonist (Ki values are 1.08 and 1750 nM for α2- and α1-adrenoceptors respectively). Displays greater selectivity over α1-adrenoceptors than clonidine and UK 14,304 (1620-, 220- and 300-fold respectively). Active in vivo; displays hypotensive, bradycardic, sedative, anxiolytic, hypothermic and analgesic effects. Racemate also available.. Purity 99%. MW (observed): 236.74