Ketamine Hydrochloride Dosing for Treatment-Resistant Depression

Patient Selection and Treatment Protocol

The American Psychiatric Association supports administering intravenous ketamine hydrochloride at 0.5 mg/kg infused over 40 minutes for treatment-resistant depression 1
Patients should have at least 2 failed adequate antidepressant trials, with a minimum duration of 4-6 weeks at therapeutic doses, to confirm treatment resistance 2, 3
Moderately severe depression, as measured by standardized rating scales, is a necessary condition for initiating ketamine therapy 2
For bipolar depression, concurrent mood stabilizer therapy, such as lithium or valproate, is recommended to mitigate manic switch risk 1

The primary regimen consists of 0.5 mg/kg IV infused over 40 minutes, with a frequency of twice weekly until remission or completion of 4-6 total infusions 1
Response assessment should evaluate for a ≥50% reduction in depressive symptoms at 24 hours post-infusion 1
Alternative schedules, such as three times per week for 2 weeks, have been studied 1
Lower doses, such as 0.2-0.25 mg/kg, may be appropriate for patients with acute suicidal ideation in emergency settings, administered over 1-2 minutes 1, 4, 5

Antisuicidal effects begin within 40 minutes post-infusion, with the largest effect sizes at this timepoint 1, 4
Antidepressant effects persist for 2-3 days after a single infusion 1
Significant improvements remain through day 7 when added to ongoing antidepressant treatment 1
Psychotomimetic effects, such as hallucinations and nightmares, occur in approximately 20% and 12% of patients, respectively, at a dose of 0.5 mg/kg 4, 5

Optimal maintenance frequency should be determined by monitoring for symptom return, typically occurring 2-7 days after a single infusion 1, 5
Esketamine requires REMS certification and mandatory 2-hour post-treatment monitoring 1, 4
Long-term efficacy and safety data remain limited, with most evidence from small sample sizes 1, 4
The antisuicidal effects may be partially independent of general antidepressant effects, though this requires further investigation 1, 4