“Ketamine treatment was safe and well tolerated, and most patients reported marked improvement in work and social functioning,” wrote Paul Glue, M.D., a professor at the School of Medical Sciences at the University of Otago in New Zealand, and colleagues.
The researchers recruited patients with treatment-refractory generalized anxiety disorder (GAD) and/or social anxiety disorder (SAD) who had responded to ketamine in a previous study. Over a three-month period, the study participants were administered 1 mg/kg of ketamine by subcutaneous injection. Patients remained on current medication regimens and/or continued with ongoing psychotherapy over the course of the trial, but no new treatments were started or doses/visit schedules altered over the course of the trial.
In total, 20 patients received ketamine injections at least weekly (16 patients received one ketamine injection weekly, and four patients whose symptoms recurred at about four days received the injection twice weekly). The researchers assessed patient levels of anxiety using the Fear Questionnaire and the Hamilton Anxiety Scale before each ketamine injection, as well as one and two hours after they had received the injection. Dissociation was assessed using the Clinician Administered Dissociative States Scale.
One hour after receiving the ketamine injection, Fear Questionnaire ratings decreased by about 50%, as did Hamilton Anxiety ratings. The patients’ mean scores on the Clinician Administered Dissociative States Scale also declined over time, from 20 points at Week 1 to 8.8 points at Week 14. The most common nondissociative adverse events reported by the patients were nausea, dizziness, and blurred vision.
Of the 18 patients who completed the trial, all reported improved social and/or work functioning during the three months of maintenance treatment. Once maintenance treatment ended, five patients (25%) remained well over at least three months of follow-up. Eight patients reported partial re-emergence of anxiety symptoms, and five patients reported full re-emergence of anxiety symptoms within two weeks of their last ketamine dose.
The researchers concluded that maintenance ketamine may be a therapeutic alternative for patients with treatment-refractory GAD/SAD. “Their experience of ketamine treatment enabled them to make substantial changes to their lives (for example, employment, study, making friends, engaging socially, and travelling),” the authors wrote. “Reduced anxiety meant everyday tasks were less onerous. Most patients reported an increase in their ability to concentrate, leading to improvement in their functionality.”
Glue and another researcher for this study have contracts with Douglas Pharmaceuticals to develop novel ketamine formulations.
For related information on ketamine, see the Psychiatric News article “‘Cautious Optimism’ Marks Outlook for Ketamine, Mood Disorders.”