SKF 100398, also known as d(CH2)5Tyr(Et)VAVP, is a particular analog of arginine vasopressin (AVP). It acts as a specific antagonist, specifically targeting the antidiuretic effect caused by both exogenous and endogenous AVP.

SKF 100398 is a specific antagonist of the hydrosmotic effect of exogenous and endogenous AVP[1]. SKF 100398 (8 μg/kg; i.v.) abolishes the antidiuretic effect of AVP[1]. Animal Model: Male Sprague-Dawley rats (250-300 g)[1]Dosage: 8 μg/kg Administration: Intravenous injection Result: Completely blocked the antidiuretic effect of exogenous AVP (4 ng/kg body wt i.v.).