Ketamine Frequency Treatment for Major Depressive Disorder

Randomized, parallel-group trial comparing two dosing regimens of ketamine (0.5 mg/kg IV): six infusions every other day over 12 days versus two active infusions (days 1 and 7) with four saline placebos.

Primary population: adults 30–65 with treatment-resistant major depressive disorder without psychosis; key exclusions include bipolar disorder, psychosis, imminent suicide risk, unstable medical disease, and recent substance abuse.