Comparability of blinded remote and site-based assessments of response to adjunctive esketamine or placebo nasal spray in patients with treatment resistant depression

Functional unblinding due to treatment emergent adverse events (TEAEs) may occur with any investigational drug and poses a challenge for double-blind, placebo-controlled studies. This pilot study compared site-based Montgomery-Asberg Depression Rating Scale (MADRS) scores to remote, site-independent scores by blinded raters. Audio-digital recordings of site-based MADRS interviews were obtained from a subset of patients during a double-blind, placebo-controlled study of esketamine nasal spray or placebo spray in treatment resistant depression (Clinical Trials Registration: NCT01998958). Fourteen of 67 patients (21%) in the ITT population were randomly selected from 3 clinical trial sites. The site-based MADRS interviews were recorded at the baseline and 2 h post-dose assessments on the first intranasal dosing day. Site-independent raters scored the recordings and were blinded to treatment and all reported TEAEs, including any transient dissociative/perceptual symptoms. None of the 7 placebo-assigned patients achieved a treatment response or remission at the 2-h post-dose assessment. Four of the 7 esketamine-assigned patients (57.1%) achieved a treatment response at 2-h post-dose, and 3 patients (42.9%) achieved remission. Three esketamine-treated patients experienced transient dissociative symptoms. The remote site-independent raters essentially replicated the site-based MADRS scores and yielded a 92.9% predictive value for matching treatment response and remission rates. This small pilot study affirms that blinded remote ratings (without the likelihood of functional unblinding) are comparable to site-based ratings of efficacy of esketamine nasal spray. The audio-digital recording method offers a reasonable strategy for other studies that may also be vulnerable to functional unblinding due to distinctive TEAEs.

AMPA Receptor Activation-Independent Antidepressant Actions of Ketamine Metabolite (S)-Norketamine

BACKGROUND

Ketamine, an N-methyl-D-aspartate receptor antagonist, exerts robust antidepressant effects in patients with treatment-resistant depression. The precise mechanisms underlying ketamine's antidepressant actions remain unclear, although previous research suggests that alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) activation plays a role. We investigated whether (S)-norketamine and (R)-norketamine, the two main metabolites of (R,S)-ketamine, also play a significant role in ketamine's antidepressant effects and whether the effects are mediated by AMPAR.

METHODS

Cellular mechanisms of antidepressant action of norketamine enantiomers were examined in mice.

RESULTS

(S)-Norketamine had more potent antidepressant effects than (R)-norketamine in inflammation and chronic social defeat stress models. Furthermore, (S)-norketamine induced more beneficial effects on decreased dendritic spine density and synaptogenesis in the prefrontal cortex and hippocampus compared with (R)-norketamine. Unexpectedly, AMPAR antagonists did not block the antidepressant effects of (S)-norketamine. The electrophysiological data showed that, although (S)-norketamine inhibited N-methyl-D-aspartate receptor-mediated synaptic currents, (S)-norketamine did not enhance AMPAR-mediated neurotransmission in hippocampal neurons. Furthermore, (S)-norketamine improved reductions in brain-derived neurotrophic factor-tropomyosin receptor kinase B signaling in the prefrontal cortex of mice susceptible to chronic social defeat stress, whereas the tropomyosin receptor kinase B antagonist and a mechanistic target of rapamycin inhibitor blocked the antidepressant effects of (S)-norketamine. In contrast to (S)-ketamine, (S)-norketamine did not cause behavioral abnormalities, such as prepulse inhibition deficits, reward effects, loss of parvalbumin immunoreactivity in the medial prefrontal cortex, or baseline gamma-band oscillation increase.

CONCLUSIONS

Our data identified a novel AMPAR activation-independent mechanism underlying the antidepressant effects of (S)-norketamine. (S)-Norketamine and its prodrugs could be novel antidepressants without the detrimental side effects of (S)-ketamine.

Efficacy and Safety of Intranasal Esketamine for the Rapid Reduction of Symptoms of Depression and Suicidality in Patients at Imminent Risk for Suicide: Results of a Double-Blind, Randomized, Placebo-Controlled Study

OBJECTIVE

The authors compared the efficacy of standard-of-care treatment plus intranasal esketamine or placebo for rapid reduction of symptoms of major depression, including suicidality, among individuals at imminent suicide risk.

METHOD

In a double-blind, multicenter, proof-of-concept study, 68 participants were randomly assigned to receive esketamine (84 mg) or placebo twice weekly for 4 weeks, in addition to comprehensive standard-of-care treatment. The primary efficacy endpoint was change in score from baseline to 4 hours after initial dose on the Montgomery-Åsberg Depression Rating Scale (MADRS). Clinician global judgment of suicide risk (from the Suicide Ideation and Behavior Assessment Tool) was also assessed. Secondary endpoints included these measures at 24 hours and double-blind endpoint at day 25.

RESULTS

A significantly greater improvement in MADRS score was observed in the esketamine group compared with the placebo group at 4 hours (least-square mean difference=-5.3, SE=2.10; effect size=0.61) and at ∼24 hours (least-square mean difference=-7.2, SE=2.85; effect size=0.65), but not at day 25 (least-square mean difference=-4.5, SE=3.14; effect size=0.35). Significantly greater improvement was also observed in the esketamine group on the MADRS suicidal thoughts item score at 4 hours (effect size=0.67), but not at 24 hours (effect size=0.35) or at day 25 (effect size=0.29). Between-group reductions in clinician global judgment of suicide risk scores were not statistically different at any time point. The most common adverse events among participants in the esketamine group were nausea, dizziness, dissociation, unpleasant taste, and headache.

CONCLUSIONS

These preliminary findings indicate that intranasal esketamine compared with placebo, given in addition to comprehensive standard-of-care treatment, may result in significantly rapid improvement in depressive symptoms, including some measures of suicidal ideation, among depressed patients at imminent risk for suicide.

Sedation with propofol during ERCP: is the combination with esketamine more effective and safer than with alfentanil? Study protocol for a randomized controlled trial

Background

Endoscopic retrograde cholangiopancreatography (ERCP) is a gastrointestinal procedure that requires a relatively motionless patient during the intervention. Deep sedation by intravenous propofol combined with an opioid has recently become the preferred sedation technique. However, when high doses of propofol are used, side effects, namely respiratory depression, may occur. Esketamine has hypnotic, analgesic, and sympathomimetic effects. Our assumption is that a combination of propofol with esketamine reduces the dosage of individual drugs, thereby minimizing sedation side effects while keeping the same satisfaction level of patients and endoscopists.

Methods/design

The study will be performed as a randomized controlled multicenter trial. Patients undergoing ERCP, ≥ 18 years old, with American Society of Anesthesiologists (ASA) classification I–III will be randomized after written informed consent to group K (propofol/esketamine) or to group A (propofol/alfentanil). The primary outcome, reflecting effectiveness of sedation, is the total dose of propofol. Secondary outcome parameters are patients’ and endoscopists’ satisfaction with the procedure and the number of sedation-related pulmonary and cardiovascular events. Data on sedation-related events are collected by recording of oxygen saturation (SpO₂), respiratory rate (RR), end-tidal CO₂ (etCO₂), heart rate (HR), arrhythmias (electrocardiogram (ECG)), and non-invasive blood pressure (NIBP) measurements. Satisfaction parameters are collected by means of questionnaires before and after the procedure and on the following day.

Discussion

Esketamine is known for its effective anesthetic and analgesic effects maintaining spontaneous breathing and airway reflexes. Due to an increase in sympathetic tone, hypotension and cardiac depression is less common. Unfortunately esketamine is also known for its psychotomimetic effects. We aim to demonstrate that the combination of esketamine with propofol for sedation in patients subjected to ERCP interventions is nevertheless superior to a combination of propofol with an opioid.

Trial registration

Nederland’s Trial Register, NTR5486. Registered on 17 September 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2197-8) contains supplementary material, which is available to authorized users.

Reduction of dopamine D2/3 receptor binding in the striatum after a single administration of esketamine, but not R-ketamine: a PET study in conscious monkeys

R-ketamine appears to be a potent, long-lasting and safer antidepressant, relative to esketamine (S-ketamine), since it might be free of psychotomimetic side effects. Using [¹¹C]raclopride and positron emission tomography (PET), we investigated whether esketamine and R-ketamine can affect dopamine D_2/3 receptor binding in the conscious monkey brain. A single infusion of esketamine (0.5 mg/kg), but not R-ketamine (0.5 mg/kg), caused a reduction of binding availability of dopamine D_2/3 receptor in the monkey striatum. This study suggests that unlike to R-ketamine, esketamine can cause dopamine release in the striatum, and that its release might be associated with psychotomimetic effects of esketamine.

The effects of intranasal esketamine (84 mg) and oral mirtazapine (30 mg) on on-road driving performance: a double-blind, placebo-controlled study

RATIONALE

The purpose of this study is to evaluate the single dose effect of intranasal esketamine (84 mg) compared to placebo on on-road driving performance. Mirtazapine (oral, 30 mg) was used as a positive control, as this antidepressant drug is known to negatively affect driving performance.

METHODS

Twenty-six healthy volunteers aged 21 to 60 years were enrolled in this study. In the evening, 8 h after treatment administration, participants conducted the standardized 100-km on-road driving test. Primary outcome measure was the standard deviation of lateral position (SDLP), i.e., the weaving of the car. Mean lateral position, mean speed, and standard deviation of speed were secondary outcome measures. For SDLP, non-inferiority analyses were conducted, using +2.4 cm (relative to placebo) as a predefined non-inferiority margin for clinical relevant impairment.

RESULTS

Twenty-four participants completed the study. No significant SDLP difference was found between esketamine and placebo (p = 0.7638), whereas the SDLP after mirtazapine was significantly higher when compared to placebo (p = 0.0001). The upper limit of the two-sided 95% confidence interval (CI) of the mean difference between esketamine and placebo was +0.86 cm, i.e., <+2.4 cm, thus demonstrating that esketamine was non-inferior to placebo. Non-inferiority could not be concluded for mirtazapine (+3.15 cm SDLP relative to placebo). No significant differences in mean speed, standard deviation of speed, and mean lateral position were observed between the active treatments and placebo.

CONCLUSIONS

No significant difference in driving performance was observed 8 h after administering intranasal esketamine (84 mg) or placebo. In contrast, oral mirtazapine (30 mg) significantly impaired on road driving performance.

Intravenous Esketamine in Adult Treatment-Resistant Depression: A Double-Blind, Double-Randomization, Placebo-Controlled Study

BACKGROUND

The purpose of this study was to assess the efficacy and safety and to explore the dose response of esketamine intravenous (IV) infusion in patients with treatment-resistant depression (TRD).

METHODS

This multicenter, randomized, placebo-controlled trial was conducted in 30 patients with TRD. Patients were randomly assigned 1:1:1 to receive an IV infusion of .20 mg/kg or .40 mg/kg esketamine or placebo over 40 minutes on day 1. The primary end point was change in Montgomery-Åsberg Depression Rating Scale total score from day 1 (baseline) to day 2. Nonresponders who received placebo on day 1 were randomly assigned again 1:1 to IV esketamine .20 mg/kg or .40 mg/kg on day 4. Secondary efficacy and safety measures were also evaluated.

RESULTS

Of the enrolled patients, 97% (29 of 30) completed the study. The least squares mean changes (SE) from baseline to day 2 in Montgomery-Åsberg Depression Rating Scale total score for the esketamine .20 mg/kg and .40 mg/kg dose groups were -16.8 (3.00) and -16.9 (2.61), respectively, and showed significant improvement (one-sided p = .001 for both groups) compared with placebo (-3.8 [2.97]). Esketamine showed a rapid (within 2 hours) and robust antidepressant effect. Treatment-emergent adverse events were dose dependent. The most common treatment-emergent adverse events were headache, nausea, and dissociation; the last-mentioned was transient and did not persist beyond 4 hours from the start of the esketamine infusion.

CONCLUSIONS

A rapid onset of robust antidepressant effects was observed in patients with TRD after a 40-minute IV infusion of either .20 mg/kg or .40 mg/kg of esketamine. The lower dose may allow for better tolerability while maintaining efficacy.

Loss of parvalbumin-immunoreactivity in mouse brain regions after repeated intermittent administration of esketamine, but not R-ketamine

Clinical use of the rapid antidepressant drug ketamine is limited, due to psychotomimetic side effects. R-ketamine appears to be a potent, long-lasting and safer antidepressant, relative to S-ketamine (esketamine), since it is free of psychotomimetic side effects. Repeated, intermittent administration of esketamine (10mg/kg, once per week for 8-weeks), but not R-ketamine, caused loss of parvalbumin (PV)-immunoreactivity in the medial prefrontal cortex and hippocampus of mouse brains, regions associated with psychosis. This study suggests that repeated intermittent use of R-ketamine is safer than esketamine in the treatment of depression.