Aims: Major depressive disorder (MDD) has devastating effects on patient's quality of life (QOL). It seems that the use of ketamine in the treatment of MDD is an easy and less invasive technique compared with invasive methods, such as electroconvulsive therapy (ECT). As there were few studies in this regard, especially in Yazd province, the current study aimed to evaluate the therapeutic effect of repeated injected ketamine on patients with MDD  and resistant to treatment.
Methods: This hospital-based open-label prospective study was conducted from September 2017 to May 2019 at Comprehensive Psychiatric Center, Taft,Yazd, Iran. In this pre-and post- trial, 18 patients with a diagnosis of MDD were recruited. The patients were diagnosed with MDD based on Diagnostic and Statistical Manual of Mental Disorders (5e) text revision Adapted from American Psychiatric Association (DSM 5). The patients aged between 18 to 70 years. Patients were eligible to participate in this study if they did not have history  of physical or mental comorbidity. After completing Hamilton Depression Rating Scale  (HDRS), the patients received 0.5 mg/kg ketamine infusion over 40 minutes with vital signs monitoring. After 2.5 hours of infusion, the HDRS was re-completed. The patients, who responded to treatment (≥50% reduction in HDRS score), received the treatment on days 3, 5, 7, 9, and 11 after the start of the study. Patients were re-evaluated after receiving the last dose of ketamine.
Results: After the first ketamine infusion, 13 of 18 (72%) patients responded to treatment. A significant decrease was seen between the mean depression score before (21.6 ± 8.5) and 2.5 hours after the first injection (9.7 ± 4.8) in responded patient (p<0.001). In addition, a significant decrease was seen in all of 13 patients who continued ketamine until the 11^th day (6.3 ± 4.0) (p<0.001).
Conclusion: Findings suggested that ketamine injection was efficacious in reducing the severity of depression in patients with MDD. Due to the decrease in the average of HDRS score and the absence of significant side effects, it seems that repeated ketamine infusion therapy can be offered as a new therapy protocol for TRD.