YM218 free base is an orally active non-peptide vasopressin ( AVP ) receptor antagonist. YM218 free base has a high affinity for rat liver V1A receptors with a K i value of 0.50 nM; it has a lower affinity for rat pituitary V1B , kidney V2 , and uterine oxytocin receptors with K i values of 1510 nM, 72.2 nM, and 150 nM, respectively. YM218 free base can be used in the study of diabetes and kidney disease.