IRL 1620 is an N-succinylated endothelin-1 analogue which acts as a highly selective ETB endothelin receptor agonist, with Ki values of 0.016 and 1900 nM at ETB and ETA receptors respectively. IRL 1620 can also discriminate between two subpopulations of ETB receptors, and in vivo IRL 1620 can significantly reduce neurological and motor deficit as well as infarct volume in a pediatric rat model of cerebral ischemia.
