title: Response to a bolus of conivaptan in patients with acute hyponatremia after brain injury.
abstract: OBJECTIVE
  The aim of the study was to analyze the response to the vasopressin-receptor antagonist conivaptan in a large cohort of brain-injured patients with acute hyponatremia.
  
  
  METHODS
  The natremic response (rise in serum sodium) to an initial bolus of conivaptan was retrospectively evaluated in 124 patients over a 3-year period in our neurosciences intensive care unit. Variables associated with this response were identified using linear regression.
  
  
  RESULTS
  Median pretreatment sodium was 132 mEq/L, and duration of hyponatremia before dose was 1 day. Median natremic response was +4 mEq/L (interquartile range, 2-7 mEq/L), measured a median of 9 hours (interquartile range, 6-12 hours) after conivaptan administration. This was associated with significant urine output (median, 2.6 L over 12 hours), with degree of aquaresis associated with natremic response (regression coefficient, B = 1.8 change in sodium per liter; 95% confidence interval, 1.3-2.4; P < .001). Seventy-four patients (60%) responded with a rise of at least 4 mEq/L. Response was predicted by higher baseline urine output (B = 0.018 per mL; 0.004-0.032; P = .01) and lack of oral fluid intake (B = 2.06; 0.44-3.68; P = .01) but not tonicity of intravenous fluids or creatinine clearance.
  
  
  CONCLUSIONS
  Conivaptan given as a bolus can effectively treat acute hyponatremia in brain-injured patients.
authors.affiliation: Department of Clinical Pharmacy, Neurology/Neurosurgery Intensive Care Unit, Barnes-Jewish Hospital, Saint Louis, MO, USA.
authors.forename: Theresa
authors.initials: T
authors.lastname: Human
authors.forename: Adaeze
authors.initials: A
authors.lastname: Onuoha
authors.forename: Michael
authors.initials: M
authors.lastname: Diringer
authors.forename: Rajat
authors.initials: R
authors.lastname: Dhar
mesh_terms: D061605:Administration, Intravenous; D000328:Adult; D000368:Aged; D065092:Antidiuretic Hormone Receptor Antagonists; D001552:Benzazepines / Q000008:administration & dosage / Q000627:therapeutic use*; D001930:Brain Injuries / Q000150:complications*; D003404:Creatinine / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007010:Hyponatremia / Q000188:drug therapy* / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012964:Sodium / Q000627:therapeutic use
chemical_list: D065092:Antidiuretic Hormone Receptor Antagonists; D001552:Benzazepines; C106389:conivaptan; D012964:Sodium; D003404:Creatinine