Two Case Studies of Patients with Major Depressive Disorder Given Low-Dose (Subanesthetic) Ketamine Infusions

Physicians who care for pain also must manage comorbid depression, which if not treated, may affect the outcome of pain treatment. When treating patients suffering from complex regional pain syndrome (CRPS) with a low-dose (subanesthetic) ketamine infusion [1–3], it was observed that some patients made a significant recovery from associated depression. This recovery was not formally documented, as the primary concern was the treatment of the patient's pain. Needless to say, it was not possible to quantify to what degree depression recovery was secondary to the patient's recovery from CRPS. Based on this result, it was thought that a low-dose (subanesthetic) infusion of ketamine was worth a trial in patients who were suffering from treatment-resistant depression without other physical or psychiatric illness. Approval for this trial was obtained from the hospital research and ethics committee. Ketamine was infused intravenously to patients commencing at 15–20 mg/h (0.1–0.2 mg/kg/h) and the dose increased until a maximum tolerated dose was achieved. This dose was assumed to be a therapeutic dose and was maintained for 5 days. Patients were able to eat, drink, watch television, or read. They could feel inebriated and/or unsteady when walking. If hallucinations occurred, the dose was to be reduced. The patient's normal medications were continued as it was feared that stopping them may result in a severe depressive episode. Before and following each treatment with ketamine, at patient clinic visits, the Beck Depression Inventory (BDI) and the Hamilton Depression Rating Score (HAMD-17) were obtained. The first two patients are described in detail: Patient A is a 39-year-old, 101 kg woman with an 18-month history of depression. Her illness resulted in her …