Effectiveness and safety of repeat dose subcutaneous ketamine for treatment-resistant depression, and the impact of prior ketamine treatment: open label extension of the KADS study

The authors aimed to evaluate the effectiveness and safety of a 4-week course of subcutaneous racemic ketamine for treatment-resistant depression (TRD) and to determine if prior ketamine treatment affected subsequent responses. In their open-label extension study, they found that while a minority of participants experienced short-term clinical benefits, response rates declined significantly after treatment cessation, and prior ketamine exposure did not influence outcomes. Overall, the study reported no unexpected safety concerns, suggesting that while ketamine may provide temporary relief, its long-term effectiveness remains limited.