Safety and efficacy of maintenance ketamine treatment in patients with treatment-refractory generalised anxiety and social anxiety disorders

Objective: In this maintenance treatment study, we sought to evaluate the effect on anxiety ratings, safety and tolerability of 3months of weekly ketamine in 20 patients with treatment-refractory DSM IV generalised anxiety disorder (GAD) and/or social anxiety disorder (SAD), and subsequent assessment of remission post-treatment. Methods: This was an uncontrolled open-label study in 20 patients who had been responders in an ascending dose ketamine study. The study was undertaken in a university clinic. Patients received one or two weekly ketamine doses of 1mg/kg injected subcutaneously for 3months. Data were collected from December 2015-June 2017. Results: There were 10 women (50%) and 10 men (50%); 15 patients (75%) met criteria for GAD and 18 (90%) for SAD. One hour after dosing, Fear Questionnaire ratings decreased by similar to 50%, as did Hamilton Anxiety ratings. Clinician Administered Dissociative States Scale mean scores declined over time, from 20 points at week1 to 8.8 points at week 14. Compared with pre-dose values, mean systolic and diastolic blood pressure increased by similar to 10mmHg at 30min. The most common adverse events were nausea, dizziness and blurred vision. Of the 20 patients, 18 reported improved social functioning and/or work functioning during maintenance treatment. Conclusions: Weekly ketamine dosing was safe and well tolerated, and post-dose dissociative symptoms tended to reduce after repeated dosing. Patients reported marked improvements in functionality and in their personal lives. Maintenance ketamine may be a therapeutic alternative for patients with treatment refractory GAD/SAD. Trial Registration: http://www.anzctr.org.au/ACTRN12615000617561