title: Rapid and longer-term antidepressant effects of repeated ketamine infusions in treatment-resistant major depression.
abstract: BACKGROUND
  Ketamine is reported to have rapid antidepressant effects; however, there is limited understanding of the time-course of ketamine effects beyond a single infusion. A previous report including 10 participants with treatment-resistant major depression (TRD) found that six ketamine infusions resulted in a sustained antidepressant effect. In the current report, we examined the pattern and durability of antidepressant effects of repeated ketamine infusions in a larger sample, inclusive of the original.
  
  
  METHODS
  Participants with TRD (n = 24) underwent a washout of antidepressant medication followed by a series of up to six IV infusions of ketamine (.5 mg/kg) administered open-label three times weekly over a 12-day period. Participants meeting response criteria were monitored for relapse for up to 83 days from the last infusion.
  
  
  RESULTS
  The overall response rate at study end was 70.8%. There was a large mean decrease in Montgomery-Åsberg Depression Rating Scale score at 2 hours after the first ketamine infusion (18.9 ± 6.6, p < .001), and this decrease was largely sustained for the duration of the infusion period. Response at study end was strongly predicted by response at 4 hours (94% sensitive, 71% specific). Among responders, median time to relapse after the last ketamine infusion was 18 days.
  
  
  CONCLUSIONS
  Ketamine was associated with a rapid antidepressant effect in TRD that was predictive of a sustained effect. Future controlled studies will be required to identify strategies to maintain an antidepressant response among patients who benefit from a course of ketamine.
authors: Mood and Anxiety Disorders Program, Department of Psychiatry, Mount Sinai School of Medicine, New York, NY 10029, USA. james.murrough@mssm.edu
authors: James W
authors: JW
authors: Murrough
authors: Andrew M
authors: AM
authors: Perez
authors: Sarah
authors: S
authors: Pillemer
authors: Jessica
authors: J
authors: Stern
authors: Michael K
authors: MK
authors: Parides
authors: Marije
authors: M
authors: aan het Rot
authors: Katherine A
authors: KA
authors: Collins
authors: Sanjay J
authors: SJ
authors: Mathew
authors: Dennis S
authors: DS
authors: Charney
authors: Dan V
authors: DV
authors: Iosifescu
mesh_terms: D000328:Adult; D000928:Antidepressive Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D061218:Depressive Disorder, Treatment-Resistant / Q000188:drug therapy*; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D007649:Ketamine / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged
chemical_list: D000928:Antidepressive Agents; D007649:Ketamine