Asimadoline is a potent κ-opioid receptor (KOR) agonist (IC50s = 5.6 and 1.2 nM for guinea pig and human receptors, respectively).1 It is 501- and 498-fold selective for κ-opioid over μ- and δ-opioid receptors, respectively. Asimadoline is spasmolytic in isolated rat duodenum (IC50 = 4.2 μM) and inhibits spontaneous contractions of isolated rat uterus (IC50 = 12.7 μM). In vivo, asimadoline reduces joint damage in a rat model of arthritis induced by complete Freund's adjuvant (CFA). Asimadoline (25 mg/kg) also reduces the abdominal withdrawal reflex in a model of visceral pain induced by colonic distension in wild-type, but not KOR-/-, mice.2
1.Camilleri, M.Asimadoline, a κ-opioid agonist, and visceral sensationNeurogastroenterol. Motil.20(9)971-979(2008) 2.Larsson, M.H., Bayati, A., Lindstr?m, E., et al.Involvement of kappa-opioid receptors in visceral nociception in miceNeurogastroenterol. Motil.20(10)1157-1164(2008)