Conivaptan is an arginine vasopressin (AVP) receptor antagonist with affinity for AVP receptor subtypes V~1A~ and V~2~. The antidiuretic action of AVP is mediated through activation of the V~2~ receptor, which functions to regulate water and electrolyte balance at the level of the collecting ducts in the kidney. Antagonism of the V~2~ receptor by conivaptan promotes the excretion of free water (without loss of serum electrolytes) resulting in net fluid loss, increased urine output, decreased urine osmolality, and subsequent restoration of normal serum sodium levels. Blockade of vascular V~1A~ receptors may cause splanchnic vasodilation, and thus hypotension or variceal bleeding in patients with cirrhosis (especially those with portal hypertension).