Augmentation Therapy With Serial Intravenous Ketamine Over 18 Months in a Patient With Treatment Resistant Depression.

Major depressive disorder is a severe illness that affects 3% to 7% of adults annually in the United States. About 30% of these individuals are refractory to multiple treatment trials. Recent reports have found a significant and almost immediate improvement in depressive symptoms after single or multiple ketamine intravenous infusions (IVIs) in such patients. We present the case of A.B., a patient with treatment-resistant depression (TRD) including to subgenual deep brain stimulation, who went into remission after augmentation with 6 ketamine IVIs (0.5 mg/kg) over a 3-week period. However, she had a reemergence of depressive symptoms 4 months later and received a second series of 3 ketamine IVIs over the course of a week. A.B. again went into remission and maintained this for the next 8 months. At this time, she experienced a reemergence of depressive symptoms and was treated with the third series of ketamine IVIs (3 infusions over the course of a week). Because A.B. has now been in remission for 6 months. A.B. has received a total of 12 ketamine IVIs over the course of 18 months. No significant adverse events have occurred. To our knowledge, this is the first case of long-term ketamine efficacy as augmentation therapy in TRD over the course of 18 months. There is a need for studies examining the long-term management of TRD with IV ketamine. Guidelines for maintenance ketamine IVIs in TRD also need to be developed.