Potent and selective non-peptide vasopressin V1A receptor antagonist; devoid of agonist activity. Displays high affinity and efficacy at both rat (Ki = 1.6 nM) and human (Ki = 1.1 - 6.3 nM) V1A receptors. Potently antagonizes arginine vasopressin-induced effects in vitro (IC50 = 3.7 nM for inhibition of human platelet aggregation) and is orally active in vivo. Purity 99%. MW (observed): 620.5