Table 1

Summary of clinical perspectives on ketamine administrations for treatment-resistant mood disorders

Clinical efficacyKetamine administrations have been associated with rapid clinical improvement (within 24 h) in patients with treatment-resistant unipolar depression, bipolar depression, PTSD and those with acute suicidal ideation.
The effect of a single dose of ketamine appears to last up to 7 days in unipolar TRD and 3–4 days in bipolar depression.
Clinical factors associated with responseCommon clinical factors associated with poor response to traditional antidepressants (comorbid anxiety disorders, history of non-response to multiple antidepressants, chronic duration of depression) do not predict lower response to ketamine.
Severely depressed patients with cognitive dysfunction or anxiety may be a very good target for ketamine treatment in clinical practice.
Repeated administrationsRepeated doses of ketamine have been reported to be safe and to additionally prolong clinical response. Very limited data exists for more than 6–12 repeated ketamine administrations for mood disorders.
Response to a series of repeated ketamine administrations could be predicted after the first one or two infusions, it is generally not useful to continue ketamine administrations after non-response to initial treatments.
Alternative route of administration and dosesMost studies have tested IV ketamine administrations.
Intranasal ketamine has positive effects, comparable with IV ketamine, and is currently developed for patient self-administration.
The most commonly used dose of IV ketamine was 0.5 mg/kg, ongoing studies are testing doses in the range 0.1–1.0 mg/kg.
Safety considerationsIt is acceptable to administer ketamine in addition to ongoing antidepressant treatment.
Time-limited side effects of ketamine (experienced during the 40 min of ketamine administration and briefly afterwards) include short-lasting neuropsychiatric effects including dizziness, blurred vision, headache, nausea or vomiting, dry mouth, restlessness, and impairments in coordination and concentration, dissociation (abnormal reality perception), as well as increases in heart rate and blood pressure.
Additional monitoring should be warranted for patients with prior history of cardiovascular illnesses; previous history of psychosis may also be a relative contraindication for ketamine.
Long-term use of ketamine has been associated mild cognitive disturbances and urinary cystitis; no data exist in patients with mood disorders but such effects should be nevertheless monitored.
  • IV, intravenous; PTSD, post-traumatic stress disorder; TRD, treatment-resistant depression.