Ketamine for treatment-resistant major depressive disorder: Double-blind active-controlled crossover study

BACKGROUND

The N-methyl-D-aspartate antagonist ketamine has rapid onset antidepressant activity in treatment-resistant depression (TRD).

AIMS

To evaluate mood rating, safety and tolerability data from patients with TRD treated with ketamine and the psychoactive control fentanyl, as part of a larger study to explore EEG biomarkers associated with mood response.

METHODS

We evaluated the efficacy and safety of intramuscular racemic ketamine in 25 patients with TRD, using a double-blind active-controlled randomized crossover design. Ketamine doses were 0.5 and 1 mg/kg, and the psychoactive control was fentanyl 50 mcg, given at weekly intervals.

RESULTS/OUTCOMES

Within 1 h of ketamine dosing, patients reported reduced depression and anxiety ratings, which persisted for up to 7 days. A dose-response profile for ketamine was noted for dissociative side effects, adverse events and changes in blood pressure; however, changes in mood ratings were broadly similar for both ketamine doses. Overall, 14/25 patients (56%) were responders (⩾50% reduction at 24 h compared with baseline) for either ketamine dose for the Hospital Anxiety and Depression Scale (HADS), and 18/25 (72%) were responders for the HADS-anxiety scale. After fentanyl, only 1/25 (HADS-depression) and 3/25 (HADS-anxiety) were responders. Ketamine was generally safe and well tolerated in this population.

CONCLUSIONS

Our findings add to the literature confirming ketamine's activity against depressive and anxiety symptoms in patients with TRD.

Ageing badly: indicators of old-age structure in Australia and New Zealand

INTRODUCTION Until 2050, Australia and New Zealand will experience continuing increase in the population aged >65 years. Studying differences in indicators of old-age structure between these countries can inform policymakers. AIM To calculate and analyse indicators of old-age structure for Australia and New Zealand. METHODS Five indicators of old-age structure were calculated: centenarian ratio (number of centenarians per 100,000 people), longevity index (proportion of people aged ≥90 and ≥65 years in the population), longevity level (proportion of 80+/60+ years population), ageing tendency (proportion of people aged ≥60 years in the population) and centenarity index (ratio between the centenarians and the total population ≥90 years). RESULTS All indicators of old-age structure demonstrated an advantageous ageing structure in Australia compared with New Zealand. In addition, the New Zealand Māori and Australian Aboriginal indicators of old-age structure demonstrated a significant disadvantage to these ethnic groups compared with the general population. DISCUSSION Public health policy needs to target ageing in New Zealand as a major goal in advancing the 'Ageing Well' policy advocated by the government.

Anxiolytic effects of acute and maintenance ketamine, as assessed by the Fear Questionnaire subscales and the Spielberger State Anxiety Rating Scale

BACKGROUND

Ketamine has rapid anxiolytic effects in treatment-resistant obsessive compulsive, post-traumatic stress, generalised anxiety and social anxiety disorders.

OBJECTIVES

This study aimed to assess changes following acute and maintenance ketamine therapy on the Fear Questionnaire (FQ) subscales and the Spielberger State Anxiety Inventory (SSAI).

METHODS

This secondary analysis used data from a mixed open-label and double-blinded placebo-controlled study. A total of 24 patients received short-term ascending subcutaneous doses of ketamine and were then eligible to enter a 3-month maintenance phase of 1 mg/kg ketamine dosed once or twice weekly. FQ and SSAI data were analysed using mixed models to identify between-dose differences and to describe trends during maintenance.

RESULTS

Acute ketamine dosing showed a rapid dose-related reduction in all three FQ subscales (agoraphobia, social phobia and blood-injury phobia) and in the SSAI. A progressive decrease in pre-dose rating-scale scores was evident during the 3 months of maintenance therapy.

CONCLUSIONS

Ketamine demonstrated dose-related improvements in all FQ subscales and in the SSAI. Both scales appear to be suitable tools to assess the anxiolytic effects of ketamine in patients with treatment-resistant anxiety. Furthermore, ketamine appears to have broad, dose-related anti-phobic effects. These findings raise the possibility that ketamine may have therapeutic potential in the treatment of other phobic states, such as specific phobia.

Effects of ketamine in patients with treatment-refractory generalized anxiety and social anxiety disorders: Exploratory double-blind psychoactive-controlled replication study

BACKGROUND

We previously reported that ketamine has anxiolytic effects in patients with treatment-resistant generalized anxiety and social anxiety disorders.

AIMS

The purpose of this study was to replicate our earlier report about ketamine's anxiolytic activity, using a more robust study design.

METHODS

This was a double-blind, psychoactive-controlled ascending dose study in 12 patients with treatment-resistant generalized anxiety and social anxiety disorders who were not currently depressed. Ascending doses of ketamine (0.25, 0.5, 1 mg/kg) were administered at weekly intervals, and midazolam 0.01 mg/kg, the control, was randomly inserted into the ketamine dose sequence. Assessments included ratings of anxiety and dissociation, safety and tolerability, and blood samples for ketamine pharmacokinetics and BDNF concentrations.

RESULTS

Improvements in anxiety ratings occurred within an hour of ketamine dosing, and persisted for up to 1 week. A dose-response profile was noted for anxiolytic effects, dissociative side effects, and changes in blood pressure and heart rate after ketamine dosing. Midazolam had minor brief effects on anxiety ratings. Ketamine was safe and well tolerated. Ketamine pharmacokinetics were correlated with dissociation ratings. Serum BDNF concentrations declined over time and were similar for all treatments.

CONCLUSIONS

Ketamine may be a potential therapeutic option for patients with treatment-resistant generalized anxiety and social anxiety disorders.

Safety and efficacy of extended release ketamine tablets in patients with treatment-resistant depression and anxiety: open label pilot study

BACKGROUND

Ketamine's defining side effects are dissociation and increased blood pressure/heart rate. An oral formulation with delayed absorption could minimize these effects. We recently reported safety and tolerability data for an extended release ketamine tablet in healthy volunteers.

METHODS

To assess safety, tolerability, efficacy, and pharmacokinetics of an extended release oral ketamine tablet in patients with treatment-resistant depression/anxiety. This was a multiple dose open-label flexible dose uncontrolled study in seven patients with treatment-resistant depression/anxiety, who had all previously demonstrated mood improvement to subcutaneous ketamine. Assessments included ratings of anxiety, depression and dissociation, safety and tolerability, and blood samples for ketamine pharmacokinetics and brain-derived neurotrophic factor (BDNF) concentrations.

RESULTS

Improvements in anxiety and depression ratings occurred gradually over 96 h; all patients had >50% improvements in mood ratings. Ketamine was safe and well tolerated, with no changes in vital signs, and a single brief report of dissociation. Ketamine may induce its own metabolism, as the ratio of norketamine to ketamine increased out to 96 h. Serum BDNF concentrations did not change during the study.

CONCLUSION

Ketamine's safety/tolerability may be improved with an extended release oral formulation. Onset of mood improvement is slightly delayed compared with parenteral dosing. These data support the further development of extended release ketamine tablets for treatment of resistant depression and anxiety disorders.

Ketamine Effects on EEG during Therapy of Treatment-Resistant Generalized Anxiety and Social Anxiety

BACKGROUND

Ketamine is swiftly effective in a range of neurotic disorders that are resistant to conventional antidepressant and anxiolytic drugs. The neural basis for its therapeutic action is unknown. Here we report the effects of ketamine on the EEG of patients with treatment-resistant generalized anxiety and social anxiety disorders.

METHODS

Twelve patients with refractory DSM-IV generalized anxiety disorder and/or social anxiety disorder provided EEG during 10 minutes of relaxation before and 2 hours after receiving double-blind drug administration. Three ascending ketamine dose levels (0.25, 0.5, and 1 mg/kg) and midazolam (0.01 mg/kg) were given at 1-week intervals to each patient, with the midazolam counterbalanced in dosing position across patients. Anxiety was assessed pre- and postdose with the Fear Questionnaire and HAM-A.

RESULTS

Ketamine dose-dependently improved Fear Questionnaire but not HAM-A scores, decreased EEG power most at low (delta) frequency, and increased it most at high (gamma) frequency. Only the decrease in medium-low (theta) frequency at right frontal sites predicted the effect of ketamine on the Fear Questionnaire. Ketamine produced no improvement in Higuchi's fractal dimension at any dose or systematic changes in frontal alpha asymmetry.

CONCLUSIONS

Ketamine may achieve its effects on treatment-resistant generalized anxiety disorder and social anxiety disorder through related mechanisms to the common reduction by conventional anxiolytic drugs in right frontal theta. However, in the current study midazolam did not have such an effect, and it remains to be determined whether, unlike conventional anxiolytics, ketamine changes right frontal theta when it is effective in treatment-resistant depression.

Ketamine's dose-related effects on anxiety symptoms in patients with treatment refractory anxiety disorders

The N-methyl-D-aspartate receptor antagonist ketamine has rapid onset activity in treatment-resistant depression, post-traumatic stress disorder and obsessive compulsive disorder. Due to similarities in brain network activity in depression and anxiety disorders, we hypothesized that ketamine might also be active in other refractory anxiety disorders. We evaluated the efficacy and safety of ketamine in 12 patients with refractory generalized anxiety disorder and/or social anxiety disorder who were not currently depressed, using an ascending single dose study design (0.25, 0.5, 1 mg/kg administered subcutaneously) at weekly intervals. Within 1 h of dosing, patients reported reduced anxiety, which persisted for up to seven days. A dose-response profile was noted for anxiolytic effects, dissociative side effects, and changes in blood pressure and heart rate, with minor changes at 0.25 mg/kg, and progressively greater and more durable changes at the higher doses. Ten of 12 patients were treatment responders at 0.5-1 mg/kg. Ketamine was safe and well tolerated in this population. Ketamine may be a potential therapeutic alternative for patients with refractory generalized anxiety disorder/social anxiety disorder. Along with its demonstrated effectiveness in patients with treatment-resistant depression, obsessive compulsive disorder and post-traumatic stress disorder, these data raise the intriguing possibility that ketamine may have broad efficacy in disorders characterized by negative emotional states, and that these disorders may share a common precipitating neurobiology.

Effect of ketamine dose on self-rated dissociation in patients with treatment refractory anxiety disorders

Patients receiving ketamine for refractory depression and anxiety report dissociative symptoms in the first 60 min post-dose. The most commonly used instrument to assess this is the Clinician-Administered Dissociative States Scale (CADSS), developed based on the assessment of patients with dissociative symptoms. Its psychometric properties for ketamine-induced dissociation have not been reported. We evaluated these from a study using 0.25-1 mg/kg ketamine and midazolam (as an active control) in 18 patients with treatment-resistant anxiety. Dissociation ratings were increased by ketamine in a dose-dependent manner. In contrast, midazolam showed no effect on ratings of dissociation. For individual CADSS items, the magnitude of change and the ketamine dose at which changes were observed were not homogenous. The Cronbach alpha for the total scale was high (0.937), with acceptable item-rest correlations for almost all individual items. Purposefully removing items to maximise alpha did not lead to meaningful improvements. Acceptable internal consistency was still observed after removing items which lacked evidence of responsiveness at lower doses. The high Cronbach alpha values identified in this study suggests that the CADSS is an internally consistent instrument for evaluating ketamine-induced dissociation in clinical trials in anxiety, although it does not capture symptoms such as thought disorder.