title: Therapeutic effect of conivaptan bolus dosing in hyponatremic neurosurgical patients.
abstract: OBJECTIVE
  To determine the natremic response of a single 20-mg bolus dose of conivaptan, an arginine vasopressin antagonist, in hyponatremic neurosurgical patients with the syndrome of inappropriate antidiuretic hormone secretion (SIADH).
  
  
  METHODS
  Retrospective medical record review.
  
  
  METHODS
  Neurosurgical intensive care unit of a tertiary care referral hospital.
  
  
  METHODS
  Thirty-two hyponatremic patients with SIADH who were admitted to the neurosurgical intensive care unit and received a single 20-mg bolus dose of conivaptan between January and December 2011.
  
  
  RESULTS
  Each patient's natremic response over 48 hours was determined. The primary end point was an increase in serum sodium level of 4 mEq/L or greater over the first 24 hours. The mean ± SD baseline serum sodium level was 129.8 ± 3.4 mEq/L, which increased to 133.1 ± 3.2 mEq/L at 6 hours after administration of the bolus dose of conivaptan. The serum sodium level at 24 hours was 134.2 ± 3.2 mEq/L, indicating a 24-hour natremic response of 4.3 ± 2.6 mEq/L (range 1-13 mEq/L) from baseline (p<0.001). Eighteen patients (56%) met the primary end point. The mean ± SD fluid balance over the first 24 hours was -783 ± 440 ml. The mean ± SD change in serum sodium level from 24 to 48 hours was 0.5 ± 1.3 mEq/L. No adverse effects or injection-site reactions were noted. The patients who failed to reach the primary end point were treated with repeated doses of conivaptan plus other agents.
  
  
  CONCLUSIONS
  We recommend a single 20-mg dose of conivaptan as the preferred initial approach to treating patients with SIADH who are in the neurosurgical intensive care unit. The 24-hour natremic response should then dictate whether additional doses of conivaptan or other therapeutic interventions are required. We believe that such an approach is safe and will result in a controlled and predictable increase in the serum sodium concentration.
authors: Division of Pulmonary and Critical Care Medicine, Eastern Virginia Medical School, Norfolk, Virginia 23507, USA. marikpe@evms.edu
authors: Paul E
authors: PE
authors: Marik
authors: Racquel
authors: R
authors: Rivera
mesh_terms: D000368:Aged; D065092:Antidiuretic Hormone Receptor Antagonists; D001552:Benzazepines / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007010:Hyponatremia / Q000188:drug therapy* / Q000601:surgery*; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000009:adverse effects; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D065092:Antidiuretic Hormone Receptor Antagonists; D001552:Benzazepines; C106389:conivaptan