title: A vasopressin receptor antagonist (VPA-985) improves serum sodium concentration in patients with hyponatremia: a multicenter, randomized, placebo-controlled trial.
abstract: Hyponatremia in advanced cirrhosis and ascites or congestive heart failure (CHF) is the result of an inappropriate increase in vasopressin secretion, which acts through activation of specific V(2) receptors in the distal renal nephron to increase water reabsorption. This study investigates the efficacy and safety of 3 different doses of the V(2) receptor antagonist, VPA-985, in correcting hyponatremia over a 7-day inpatient study period. Forty-four hospitalized patients (33 patients with cirrhosis, 6 with CHF, and 5 with syndrome of inappropriate antidiuretic hormone (SIADH) were studied on a constant sodium intake, with VPA doses of 25, 125, and 250 mg twice daily or placebo. Serum sodium measurements were repeated after every daily dose, and the next dose withheld for excessive serum sodium rises. Fluid intake was adjusted according to previous 24-hour urinary outputs. Adverse events were based on clinical signs of dehydration or encephalopathy. VPA-985 produced a significant overall aquaretic response compared with placebo, with significant dose related increases in free water clearance (P <.05) and serum sodium (P <.05), without significant changes in orthostatic blood pressure or serum creatinine levels. Five patients (50%) on 250 mg twice daily had to have medication withheld on multiple occasions. End-of-study plasma vasopressin levels increased significantly in the 2 larger dose groups. In conclusion, VPA-985 appears effective and safe in appropriate doses in correcting abnormal renal water handling and hyponatremia in conditions associated with water retention. Higher doses of VPA-985 may produce significant dehydration and will require close monitoring with their use.
authors.affiliation: Department of Medicine, Toronto General Hospital, University of Toronto, Canada. florence.wong@utoronto.ca
authors.forename: Florence
authors.initials: F
authors.lastname: Wong
authors.forename: Andres T
authors.initials: AT
authors.lastname: Blei
authors.forename: Laurence M
authors.initials: LM
authors.lastname: Blendis
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Thuluvath
mesh_terms: D000450:Aldosterone / Q000097:blood; D065092:Antidiuretic Hormone Receptor Antagonists; D001201:Ascites / Q000150:complications; D001381:Azepines / Q000008:administration & dosage* / Q000009:adverse effects; D001549:Benzamides / Q000008:administration & dosage* / Q000009:adverse effects; D004487:Edema / Q000097:blood / Q000188:drug therapy / Q000209:etiology; D005260:Female; D006333:Heart Failure / Q000150:complications; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007010:Hyponatremia / Q000097:blood / Q000188:drug therapy* / Q000209:etiology; D007177:Inappropriate ADH Syndrome / Q000097:blood / Q000188:drug therapy / Q000209:etiology; D008103:Liver Cirrhosis / Q000150:complications; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood; D011758:Pyrroles; D012083:Renin / Q000097:blood; D012964:Sodium / Q000097:blood*; D013894:Thirst / Q000187:drug effects; D016896:Treatment Outcome; D014882:Water-Electrolyte Balance / Q000187:drug effects; D001569:Benzodiazepines
chemical_list: D000450:Aldosterone; D065092:Antidiuretic Hormone Receptor Antagonists; D001381:Azepines; D001549:Benzamides; D009638:Norepinephrine; D011758:Pyrroles; D012083:Renin; D012964:Sodium; C409452:lixivaptan; D001569:Benzodiazepines