Ornipressin (acetate)

Ornipressin is an agonist of the vasopressin V_1A receptor and a synthetic peptide derivative of argipressin containing an arginine-to-ornithine substitution at position eight.¹ It selectively induces reporter gene expression in HEK293 cells expressing vasopressin V_1A and V₂ receptors (EC₅₀s = 0.69 and 0.45 nM, respectively, for the human receptors) over cells expressing vasopressin V_1B receptors.² It is selective for vasopressin V_1A and V₂ receptors over the vasopressin V_1B receptor and oxytocin receptor (EC₅₀s = 7.5 and 71 nM, respectively, for the human receptors). Ornipressin increases arterial blood pressure in rats when administered at a dose of 0.1 nmol/kg.