Oral ketamine for the treatment of pain and treatment-resistant depression†

Oral esketamine in patients with treatment-resistant depression: a double-blind, randomized, placebo-controlled trial with open-label extension

About one-third of patients with depression do not achieve adequate response to current treatment options. Although intravenous and intranasal administrations of (es)ketamine have shown antidepressant properties, their accessibility and scalability are limited. We investigated the efficacy, safety, and tolerability of generic oral esketamine in patients with treatment-resistant depression (TRD) in a randomized placebo-controlled trial with open-label extension. This study consisted of 1) a six-week fixed low-dose treatment phase during which 111 participants received oral esketamine 30 mg or placebo three times a day; 2) a four-week wash-out phase; and 3) an optional six-week open-label individually titrated treatment phase during which participants received 0.5 to 3.0 mg/kg oral esketamine two times a week. The primary outcome measure was change in depressive symptom severity, assessed with the Hamilton Depression Rating Scale (HDRS17), from baseline to 6 weeks. Fixed low-dose oral esketamine when compared to placebo had no benefit on the HDRS17 total score (p = 0.626). Except for dizziness and sleep hallucinations scores, which were higher in the esketamine arm, we found no significant difference in safety and tolerability aspects. During the open-label individually titrated treatment phase, the mean HDRS17 score decreased from 21.0 (SD 5.09) to 15.1 (SD 7.27) (mean difference -6.0, 95% CI -7.71 to -4.29, p < 0.001). Our results suggest that fixed low-dose esketamine is not effective in TRD. In contrast, individually titrated higher doses of oral esketamine might have antidepressant properties.

Extended-release ketamine tablets for treatment-resistant depression: a randomized placebo-controlled phase 2 trial

Ketamine has rapid-onset antidepressant activity in patients with treatment-resistant major depression (TRD). The safety and tolerability of racemic ketamine may be improved if given orally, as an extended-release tablet (R-107), compared with other routes of administration. In this phase 2 multicenter clinical trial, male and female adult patients with TRD and Montgomery-Asberg Depression Rating Scale (MADRS) scores ≥20 received open-label R-107 tablets 120 mg per day for 5 days and were assessed on day 8 (enrichment phase). On day 8, responders (MADRS scores ≤12 and reduction ≥50%) were randomized on a 1:1:1:1:1 basis to receive double-blind R-107 doses of 30, 60, 120 or 180 mg, or placebo, twice weekly for a further 12 weeks. Nonresponders on day 8 exited the study. The primary endpoint was least square mean change in MADRS for each active treatment compared with placebo at 13 weeks, starting with the 180 mg dose, using a fixed sequence step-down closed test procedure. Between May 2019 and August 2021, 329 individuals were screened for eligibility, 231 entered the open-label enrichment phase (days 1-8) and 168 responders were randomized to double-blind treatment. The primary objective was met; the least square mean difference of MADRS score for the 180 mg tablet group and placebo was -6.1 (95% confidence interval 1.0 to 11.16, P = 0.019) at 13 weeks. Relapse rates during double-blind treatment showed a dose response from 70.6% for placebo to 42.9% for 180 mg. Tolerability was excellent, with no changes in blood pressure, minimal reports of sedation and minimal dissociation. The most common adverse events were headache, dizziness and anxiety. During the randomized phase of the study, most patient dosing occurred at home. R-107 tablets were effective, safe and well tolerated in a patient population with TRD, enriched for initial response to R-107 tablets. ClinicalTrials.gov registration: ACTRN12618001042235 .

Oral prolonged-release ketamine in treatment-resistant depression - A double-blind randomized placebo-controlled multicentre trial of KET01, a novel ketamine formulation - Clinical and safety results

INTRODUCTION

We investigated the antidepressant effects of a novel oral prolonged-release formulation of racemic ketamine (KET01) in patients suffering from treatment-resistant depression (TRD) as add-on therapy.

MATERIAL AND METHODS

Patients were randomized to an additional 160 mg/day or 240 mg/day KET01 or placebo for 14 days. The primary endpoint was change in Montgomery-Åsberg Depression Rating Scale (MADRS) scores from baseline to day 15. For treatment group comparisons, we used ANOVA with pairwise least squares mean difference tests in a mixed model repeated measures analysis.

RESULTS

Twenty-seven patients completed the double-blind protocol before trial premature termination due to poor recruitment during the COVID-19 pandemic. Mean (SD) MADRS scores on day 15 were 23 (10.32) in placebo, 25 (8.28) with 160 mg/day and 17 (10.32) with 240 mg/day KET01. MADRS change was numerically larger but statistically non-significant in the 240 mg/day KET01 group vs placebo on day 7 (-5.67; p = 00.106) and day 15 was (difference: 4.99; p = 00.15). In exploratory analysis, baseline leukocyte count correlated with response to KET01 (p = 00.01). Distribution of adverse event rates were comparable between the treatment arms. Safety analysis did not identify increased risk of suicidality, dissociation, hear rate, systolic and diastolic blood pressure associated with trial treatment.

DISCUSSION

Our results suggest that adjunctive oral administration of prolonged-release ketamine at a dose of 240 mg/day shows a positive, although statistically non-significant, trend towards antidepressant efficacy, however, the benefit could not be confirmed due to premature trial termination. Given its ease of use and low side effects, further trials are warranted to investigate this route of ketamine administration as a promising potential treatment of TRD.

Oral ketamine for depression: An updated systematic review

Objectives: Ketamine is a glutamate N-methyl-D-aspartate receptor antagonist that can be used to treat major depressive disorder by single or repeated infusions. However, the accessibility and scalability of oral ketamine make it preferred over intravenous ketamine. In this systematic review, we aim to evaluate the efficacy, tolerability, and safety of oral ketamine, esketamine and r-ketamine for unipolar and bipolar depression. Materials and methods: Electronic databases were searched from inception to September 2022 to identify relevant articles. Results: Twenty-two studies, including four randomized clinical trials (RCTs), one case series, six case reports, five open-label trials and six retrospective chart review studies involving 2336 patients with depression were included. All included studies reported significant improvement following ketamine administration. Ketamine was well tolerated without serious adverse events. However, RCTs had a high risk of bias due to analysis methods and adverse events monitoring. Ketamine dosage varied from 0.5 to 1.25 mg/kg. The frequency of administration was daily to monthly. Several important limitations were identified, most notably the small number of RCTs. Conclusions: Taken together, preliminary evidence suggests the potential for antidepressant effect of oral ketamine. However, further research with large sample size and long follow-up period is needed to better determine the antisuicidal effect and efficacy in treatment-resistant depression.

[Pain Management in Palliative Care]

Patients in the palliative phase of a disease often suffer from pain, which leads to a significant reduction in quality of life. Since in most cases there is a progression rather than an improvement of the disease over time, pain therapy must also be dynamically adapted. Due to accompanying symptoms and the physical burden of the disease, treatment of pain is often difficult. In the palliative situation, pain should not only be understood as an excitation of nociceptors but is rather also an expression of mental stress. In this article, we would like to give an overview of the available drugs, application methods and alternative treatment options. Specifically, the article is divided into the following subsections: non-opioid analgesics, opioids, co-analgesics, patient-controlled analgesia procedures, neuraxial and peripheral regional anesthesia procedures, neurolysis, supportive therapies and palliative sedation. Thus, when treating palliative patients, the focus should not only be on the one symptom of pain, but, in the sense of the bio-psycho-social model, a multimodal oriented treatment of the patient with all his symptoms, also including his relatives, must be carried out.

Pathophysiology and Current Drug Treatments for Post-Stroke Depression: A Review

Post-stroke depression (PSD) is a biopsychosocial disorder that affects individuals who have suffered a stroke at any point. PSD has a 20 to 60 percent reported prevalence among stroke survivors. Its effects are usually adverse, can lead to disability, and may increase mortality if not managed or treated early. PSD is linked to several other medical conditions, including anxiety, hyper-locomotor activity, and poor functional recovery. Despite significant awareness of its adverse impacts, understanding the pathogenesis of PSD has proved challenging. The exact pathophysiology of PSD is unknown, yet its complexity has been definitively shown, involving mechanisms such as dysfunction of monoamine, the glutamatergic systems, the gut-brain axis, and neuroinflammation. The current effectiveness of PSD treatment is about 30-40 percent of all cases. In this review, we examined different pathophysiological mechanisms and current pharmacological and non-pharmacological approaches for the treatment of PSD.

The efficacy and safety of esketamine in the treatment of major depressive disorder with suicidal ideation: study protocol for a randomized controlled trial

BACKGROUND

Major depressive disorder (MDD) is a high risk factor for suicide, with up to 20% of MDD patients attempting suicide during their lifetime. Current treatments for MDD are slow onset of action, low efficiency, and the inability to control suicidal behaviors quickly and effectively. Intravenous ketamine has been shown to have a rapid but transient antidepressant effect, but there is still lack evidence on the efficacy and safety of intravenous esketamine in reducing suicidal ideation and depressive symptoms in MDD patients with suicidal ideation. We designed a study to investigate the effect of short-term repeated intravenous infusion of esketamine three times in MDD patients with suicidal ideation.

METHODS

This study features a randomized, double-blind, placebo-controlled trial (RCT) comparing short-term repeated intravenous infusions of esketamine with placebo as a supplement to conventional antidepressants with an intervention period of 6 days and one infusion every other day, followed by 4 weeks of follow-up. These methods support the examination of the efficacy, safety, tolerability, and mechanism of action of short-term repeated intravenous infusions of esketamine in MDD patients with suicidal ideation.

DISCUSSION

This is the first RCT to explore the efficacy and safety of short-term repeated infusion of esketamine on suicidal ideation and depressive symptoms in MDD patients with suicidal ideation. If proven effective and tolerated, it will provide evidence for rapid and effective treatment of suicidal ideation and depressive symptoms in MDD individuals with suicidal ideation.

TRIAL REGISTRATION

Chinese Clinical Trial Register, ChiCTR2000041232 . Registered 22 December 2020.

Efficacy of ketamine for comorbid depression and acute or chronic pain: A systematic review

Pain and depression frequently co-occur. Due to its antidepressant and analgesic properties, ketamine has been used for the management of treatment-resistant depression and pain. This systematic review examined the literature on the efficacy of sub-anesthetic doses of ketamine in individuals experiencing comorbid depression and chronic pain (CDCP), as well as comorbid depression and acute pain (CDAP). A secondary objective was to provide an assessment of dosage, route, and adverse effects of ketamine treatment for CDCP and CDAP. A literature search was conducted on MEDLINE, PsycINFO, and Embase databases, coupled with a manual screening of the bibliography sections of included articles. In addition, registered ongoing and planned trials were searched on Clinicaltrials.gov. The end date of the search was April 9th, 2022. Included studies assessed changes in depression and pain in patients receiving at least one sub-anesthetic dose of ketamine. Assessment of quality was conducted using the GRADE checklist. Of the 7 CDCP clinical trials, 3 reported a reduction in depression and pain, 3 reported a reduction in depression or pain only, and 1 reported no improvement in either comorbidity. Among the 7 CDAP clinical trials, 4 studies found improvements in depression and pain while the remaining 3 reported improvements in only one parameter. Ten of the 12 case studies and 2 of the 3 observational studies assessing CDCP and CDAP found improvements in pain and depression scores post-treatment with effects of variable duration. The planned methodologies of the registered clinical trials are in line with those of the published research. Preliminary evidence supports the efficacy of ketamine in treating CDCP and CDAP. However, the current review identified a small number of heterogeneous studies with mixed results, preventing comprehensive conclusions. More longitudinal placebo-controlled studies are needed to identify the effects of ketamine for patients with CDCP and CDAP.

Holding on or letting go? Patient experiences of control, context, and care in oral esketamine treatment for treatment-resistant depression: A qualitative study

BACKGROUND

Ketamine and its enantiomer esketamine represent promising new treatments for treatment-resistant depression (TRD). Esketamine induces acute, transient psychoactive effects. How patients perceive esketamine treatment, and which conditions facilitate optimal outcomes, remains poorly understood. Understanding patient perspectives on these phenomena is important to identify unmet needs, which can be used to improve (es)ketamine treatments.

AIMS

To explore the perspectives of TRD patients participating in "off label" oral esketamine treatment.

MATERIALS AND METHODS

In-depth interviews were conducted with 17 patients (11 women) after a six-week, twice-weekly esketamine treatment program, and subsequently after six months of at-home use. Interviews explored participants' perspectives, expectations, and experiences with esketamine treatment. Audio interviews were transcribed verbatim and analysed following an Interpretative Phenomenological Analysis (IPA) framework.

RESULTS

Key themes included overwhelming experiences; inadequate preparation; letting go of control; mood states influencing session experiences; presence and emotional support, and supportive settings. Patients' attempts to let go and give into vs. attempts to maintain control over occasionally overwhelming experiences was a central theme. Multiple factors influenced patients' ability to give into the experience and appeared to impact their mood and anxiety about future sessions, including level of preparation and education, physical and emotional support, and setting during the session.

CONCLUSION

Better preparation beforehand, an optimized treatment setting, and emotional and psychological support during (es)ketamine sessions can help patients to "let go" and may lead to better quality of care and outcomes. Recommendations to improve quality of patient care in (es)ketamine treatment are provided, including suggestions for the training of nurses and other support staff.

Psychedelics for the treatment of depression, anxiety, and existential distress in patients with a terminal illness: a systematic review

BACKGROUND

Terminally ill patients may experience existential distress, depression, or anxiety, limiting quality of life in the final stage. Existing psychotherapeutic or pharmacological interventions have (time) limited efficacy. Psychedelic treatment may be a safe and effective alternative treatment option.

AIM

Systematically review studies on psychedelic treatment with and without psychotherapy for existential distress, depression, and anxiety in terminally ill patients.

METHODS

Medline, PsycINFO, and Embase were searched for original-data studies on the treatment of depression, anxiety, and existential distress with classical or a-typical psychedelics in patients with a terminal illness, using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

A total of 1850 records were screened, and 33 articles were included in this review: 14 studies on classical psychedelics (DPT, LSD, and psilocybin) and 19 studies on atypical psychedelics (MDMA and ketamine). Results of early pre-post studies are promising but have serious methodological flaws. Recent (controlled) trials with LSD, psilocybin, ketamine, and MDMA are of higher methodological quality and indicate positive effects on existential and spiritual well-being, quality of life, acceptance, and reduction of anxiety and depression with few adverse and no serious adverse effects.

CONCLUSIONS

Both classical and a-typical psychedelics are promising treatment options in patients with terminal illness. To draw final conclusions on effectiveness and safety of psychedelics, we need larger high-quality studies for classical psychedelics and MDMA. Ketamine studies should pay more attention to existential dimensions of well-being and the psychotherapeutic context of the treatment.

Repeated, low-dose oral esketamine in patients with treatment-resistant depression: pilot study

BACKGROUND

Intravenous infusion of ketamine can produce rapid and large symptom reduction in patients with treatment-resistant depression (TRD) but presents major obstacles to clinical applicability, especially in community settings. Oral esketamine may be a promising addition to our TRD treatment armamentarium.

AIMS

To explore the safety, tolerability and potential clinical effectiveness of a 3-week treatment with repeated, low-dose oral esketamine.

METHOD

Seven patients with chronic and severe TRD received 1.25 mg/kg generic oral esketamine daily, over 21 consecutive days. Scores on the Systematic Assessment for Treatment Emergent Events (SAFTEE), Community Assessment of Psychic Experiences (CAPE), Clinician Administered Dissociative States Scale (CADSS) and Hamilton Rating Scale for Depression (HRSD) instruments, as well as blood pressure and heart rate, were repeatedly assessed.

RESULTS

Treatment with oral esketamine was well-tolerated. No serious side-effects occurred, and none of the participants discontinued treatment prematurely. Psychotomimetic effects were the most frequently reported adverse events. Mean HDRS score decreased by 16.5%, from 23.6 to 19.7. Three participants showed reductions in HDRS scores above the minimum clinically important difference (eight-point change), of whom two showed partial response. No participants showed full response or remission.

CONCLUSIONS

These results strengthen the idea that oral esketamine is a safe and well-tolerated treatment for patients with chronic and severe TRD, but therapeutic effects were modest. Results were used to design a randomised controlled trial that is currently in progress.

Targeting inflammation in depression: Ketamine as an anti-inflammatory antidepressant in psychiatric emergency

Major depressive disorder (MDD) is a common psychiatric disorder with multifactorial aetiology and complex pathophysiology. Despite availability of various pharmacological and non-pharmacological therapeutic strategies, treatment resistant depression (TRD) remains a significant challenge with specific concern for those patients with severe depressive symptoms in particular suicidal ideations who require immediate and effective intervention. Inflammation has been widely studied for its association with MDD and treatment response. Ketamine known as a dissociative anaesthetic has a novel rapid-acting antidepressant effect at lower doses. Anti-inflammatory actions of ketamine appear to play a role in mechanisms underlying its antidepressant effects. Considering the rapid antidepressant action of ketamine, this review provides a brief overview of antidepressant properties of ketamine as well as its effects on peripheral and central inflammation to better understand the mechanisms underlying the therapeutic action of ketamine as an anti-inflammatory antidepressant target in psychiatric emergency. Development of effective medications, which act rapidly with dual effect on both inflammation and MDD would be of a significant clinical importance for a successful and personalised treatment of inflammatory-induced TRD and suicidal thoughts and behaviour.

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Anti-inflammatory actions of ketamine play a role in mechanisms underlying its antidepressant effects.

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Ketamine’s dual effect on inflammation and depression is particularly important in treatment of inflammatory-induced TRD and suicidal patients.

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Ketamine affects CNS receptors and pathways, neurotransmitter systems, synaptogenesis, and inflammatory responses.

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Ketamine remains a promising target for treatment of TRD and suicidal thoughts.

Ketamine for the Treatment of Chronic Pain: A Comprehensive Review

Background

Chronic pain significantly worsens the quality of life. Unlike neuropathic, musculoskeletal, postoperative pain, and cancer pain, chronic primary pain cannot be explained by an underlying disease or condition, making its treatment arduous.

Objectives

This manuscript intends to provide a comprehensive review of the use of ketamine as a treatment option for specific chronic pain conditions.

Study Design

A review article.

Setting

A review of the literature.

Methods

A search was done on PubMed for relevant articles.

Results

A comprehensive review of the current understanding of chronic pain and the treatment of specific chronic pain conditions with ketamine.

Limitations

Literature is scarce regarding the use of ketamine for the treatment of chronic pain.

Conclusion

First-line treatment for many chronic pain conditions includes NSAIDs, antidepressants, anticonvulsants, and opioids. However, these treatment methods are unsuccessful in a subset of patients. Ketamine has been explored in randomized controlled trials (RCTs) as an alternative treatment option, and it has been demonstrated to improve pain symptoms, patient satisfaction, and quality of life. Conditions highlighted in this review include neuropathic pain, fibromyalgia, complex regional pain syndrome (CRPS), phantom limb pain (PLP), cancer pain, and post-thoracotomy pain syndrome. This review will discuss conditions, such as neuropathic pain, fibromyalgia, complex regional pain syndrome, and more and ketamine's efficacy and its supplementary benefits in the chronic pain patient population. As the opioid crisis in the United States continues to persist, this review aims to understand better multimodal analgesia, which can improve how chronic pain is managed.

Should Ketamine Not Be Banned? A Scoping Review

OBJECTIVES

Although the importance of ketamine in clinical practice and in resource-poor settings and disaster zones, several attempts were made to reschedule it because of the issues around its misuse. Resisting future moves to reschedule ketamine is important for its continuous availability where needed. This scoping review addresses the question of whether ketamine should or should not be banned and the state of preparedness of low resource settings if ketamine petitions become successful in the future.

METHODS

A search was performed using PubMed and Google Scholar to identify articles published in the English language from March 2015 to August 2020. The articles were searched with a wide range of priori search terms related to the research questions. The selection of articles was based on relevance and eligibility.

RESULTS

Seventy-five articles were selected and grouped into 4 ethical themes. The search revealed that several articles addressed the importance of ketamine, pharmacology, misuse, supply, and consequences of a ketamine ban; however, none addressed how resource-poor countries should prepare for a future without the overreliance of ketamine.

CONCLUSION

Four ketamine petitions in about 10 years are an indication that another may resurface soon; therefore, it is important to continue to study the clinical importance of ketamine while discouraging its overreliance for clinical practice.

Comparison of Rapid Antidepressant and Antisuicidal Effects of Intramuscular Ketamine, Oral Ketamine, and Electroconvulsive Therapy in Patients With Major Depressive Disorder: A Pilot Study

PURPOSE/BACKGROUND

This study was devised to compare the antidepressant and antisuicidal effects of oral and intramuscular (IM) ketamine versus electroconvulsive therapy (ECT).

METHODS/PROCEDURES

In our pilot study, 45 patients with major depressive disorder (based on Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, criteria) in the age range of 18 to 70 years who were determined suitable candidates for ECT got randomly divided into 3 equal groups. Each group received one of these treatment modalities: 0.5 mg/kg of IM ketamine; 1 mg/kg of oral ketamine; and ECT in 6 to 9 sessions during 3 weeks. Depression and suicidal ideation scores were recorded using the Hamilton Depression Rating Scale and the Beck Scale for Suicidal Ideation, respectively, at baseline, 24 hours, 1 week, 2 weeks, and 3 weeks within the intervention. The measurements were repeated 1 week and 1 month after the end of the intervention as well. Vital signs and adverse effects were noted. Finally, satisfaction levels of patients for each method were recorded and compared between groups.

FINDINGS/RESULTS

The Hamilton Depression Rating Scale and the Beck Scale for Suicidal Ideation scores significantly improved in all groups compared with baseline with no significant differences between the 3 groups. The adverse effects for ketamine-consuming groups such as dissociative symptoms were brief and transient, whereas memory loss for the ECT group remained up to 1 month in some patients. Ketamine-receiving groups preferred it more than ECT.

IMPLICATIONS/CONCLUSIONS

Oral and IM ketamine probably have equal antidepressant in addition to more antisuicidal effects compared with ECT but had less cognitive adverse effects and higher preference by patients. Thereby, ketamine can be an alternative method in the treatment of patients with severe and/or suicidal MDD.

Harm related to recreational ketamine use and its relevance for the clinical use of ketamine. A systematic review and comparison study

BACKGROUNDS

Ketamine is a dissociative anesthetic that is currently considered for several new indications.

AIM

To deduce the safety of long-term ketamine treatment using the harm of heavy recreational (non-medical) ketamine use as a proxy for maximal possible harm of ketamine treatment.

METHODS

Systematic literature review according to PRISMA guidelines to identify controlled studies on ketamine-related harm in heavy recreational ketamine users. Results were compared with serious adverse events (SAEs) in patients treated with ketamine according to three systematic reviews considering dosing regimen and cumulative dose.

RESULTS

The systematic search yielded 25 studies. Heavy recreational ketamine use can escalate to ketamine dependency and was often dose-dependently associated with other SAEs, including cognitive and mental disorders, and gastrointestinal and urinary tract symptoms, which disappeared upon marked reduction of ketamine use. Heavy ketamine users have a much higher cumulative exposure to ketamine than ketamine treated patients (>90 times), which may explain why SAEs in the clinical context are mostly mild and reversible and why ketamine dependence was not reported in these patients.

CONCLUSION

Treatment of patients with ketamine is not associated with ketamine dependency or SAEs. However, caution is needed since data on long-term clinical ketamine use with a long-term follow-up is lacking.

The Role of Microglia in Perioperative Neuroinflammation and Neurocognitive Disorders

The aseptic trauma of peripheral surgery activates a systemic inflammatory response that results in neuro-inflammation; the microglia, the resident immunocompetent cells in the brain, are a key element of the neuroinflammatory response. In most settings microglia perform a surveillance role in the brain detecting and responding to “invaders” to maintain homeostasis. However, microglia have also been implicated in producing harm possibly by changing its phenotype from its beneficial, anti-inflammatory state (termed M2) into an injurious pro-inflammatory state (termed M1); it is likely that there are intermediates states between these polar phenotypes and some consider that a gradient exists with a number of intermediates, rather than a strict dichotomy between M1 and M2. In the pro-inflammatory phenotypes, microglia can disrupt synaptic plasticity such as long- term potentiation that can result in disorders of learning and memory of the type observed in Peri-operative Neurocognitive Disorders. Therefore, investigators have sought strategies to prevent microglia from provoking this adverse event in the perioperative period. In preclinical studies microglia can be depleted by removing trophic factors required for its maintenance; subsequent repopulation with a more beneficial microglial phenotype may result in memory enhancement, improved sensory motor function, as well as suppression of neuroinflammatory and oxidative stress pathways. Another approach consists of preventing microglial activation using the non-specific P38 MAP kinase blockers such as minocycline. Perhaps a more physiologic approach is the use of inhibitors of potassium (K⁺) channels that are required to convert the microglia into an active state. In this context the specific K⁺ channels that are implicated are termed Kv1.3 and KCa3.1 and high selective inhibitors for each have been developed. Data are accumulating demonstrating the utility of these K⁺ channel blockers in preventing Perioperative Neurocognitive Disorders.

Oral S-ketamine effective after deep brain stimulation in severe treatment-resistant depression and extensive comorbidities

This case report describes successful maintenance treatment with oral S-ketamine in a patient with severe depression, who previously was resistant to electroconvulsive therapy and deep brain stimulation, and who also had comorbid psychotic and obsessive compulsive symptoms.

Influence of formulation and route of administration on ketamine's safety and tolerability: systematic review

PURPOSE

Ketamine has rapid-onset antidepressant effects in patients with treatment-resistant depression. Common side effects include dissociation (a sense of detachment from reality) and increases in systolic and diastolic blood pressure. The objective of this structured review was to examine the effect of ketamine formulation and route of administration on its pharmacokinetics, safety and tolerability, to identify formulation characteristics and routes of administration that might minimise side effects.

METHODS

This was a structured review of published ketamine pharmacokinetics, safety and tolerability data for any ketamine formulation. The ratio of ketamine:norketamine was calculated from reported C_max values, as a measure of first pass metabolism. The effect of formulation and route of administration on safety was evaluated by measuring mean changes in systolic blood pressure and tolerability by changes in dissociation ratings. Data were correlated using Spearman's method.

RESULTS

A total of 41 treatment arms were identified from 21 publications, and included formulation development studies in healthy volunteers, and studies in clinical populations (patients undergoing anaesthesia, or being treated for pain or depression). Ketamine:norketamine ratios were strongly positively correlated with change in dissociation ratings (r = 0.89) and change in blood pressure (r = 0.96), and strongly negatively correlated with ketamine T_max (r = - 0.87; p < 0.00001 for all). Ketamine T_max strongly positively correlated with a change in dissociation ratings (r = - 0.96) and change in blood pressure (r = - 0.99; p < 0.00001 for all).

CONCLUSION

Ketamine formulations that maximize first pass metabolism and delay T_max will be better tolerated and safer than formulations which lack those characteristics.

Ifenprodil rapidly ameliorates depressive-like behaviors, activates mTOR signaling and modulates proinflammatory cytokines in the hippocampus of CUMS rats

RATIONALE

The rapid-onset and long-lasting antidepressant properties of ketamine have prompted investigations into a variety of agents that target N-methyl-D-aspartate receptors (NMDARs) for the treatment of major depressive disorder (MDD). According to the literature, ifenprodil (a GluN2B-containing NMDAR antagonist) can potentiate the antidepressant-like effects of certain antidepressant drugs in mice. Here, we report that a single injection of ifenprodil (3 mg/kg, intraperitoneally (i.p.)) was sufficient to provoke rapid antidepressant-like effects in chronic unpredictable mild stress (CUMS) rats. Moreover, ifenprodil activated mTOR signaling and reversed the CUMS-induced elevation of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in the hippocampus after acute administration. Unfortunately, in our study, ifenprodil had no influence on corticosterone levels in the plasma. Our data indicate that ifenprodil per se might exert antidepressant-like effects by modulating neuroplasticity and inflammatory processes rather than the typical hormonal factors affected by stressors.

OBJECTIVES

To explore the potential rapid antidepressant-like effects and mechanisms of ifenprodil, a GluN2B subunit-selective NMDAR antagonist.

METHODS

Male Sprague-Dawley rats were used in 3 separate experiments. In experiment 1, we used the forced swim test (FST) and sucrose preference test (SPT) to identify the rapid antidepressant-like effects of ifenprodil in chronic unpredictable mild stress (CUMS) rats after acute administration. In experiment 2, we assessed neurochemical changes involved in synaptic plasticity within the hippocampus of CUMS rats. In experiment 3, we assessed the levels of corticosterone in the plasma and proinflammatory cytokines in the hippocampus in CUMS rats after ifenprodil treatment.

RESULTS

Ifenprodil rapidly ameliorated depressive-like behaviors in the FST and SPT, activated mTOR signaling, dephosphorylated eukaryotic elongation factor 2, enhanced BDNF expression, and promoted the synthesis of the synaptic protein GluA1 synthesis after acute administration. Moreover, ifenprodil reversed the CUMS-induced elevation of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in the hippocampus after acute administration. Unfortunately, ifenprodil had no influence on corticosterone levels in the plasma in our study.

CONCLUSIONS

Our data indicate that ifenprodil per se might exert antidepressant-like effects through its effects on neuroplasticity and inflammatory processes rather than the typical hormonal factors affected by stressors.

Next-Step Treatment Considerations for Patients With Treatment-Resistant Depression That Responds to Low-Dose Intravenous Ketamine

Numerous short-term randomized trials support the acute-phase efficacy of low-dose intravenous (IV) ketamine for patients with treatment-resistant unipolar or bipolar depression. Ketamine's antidepressive effects generally have limited duration, highlighting the need for maintenance treatment after an acute-phase response. It is increasingly likely that psychiatrists will be called upon to manage the care of patients with treatment-resistant unipolar or bipolar depression who have responded acutely to ketamine and to recommend or initiate next-step treatments. However, there is a paucity of controlled evidence to guide best practices for managing treatment of patients with treatment-resistant unipolar or bipolar depression who have had a positive initial response to ketamine. This article reviews the available evidence supporting specific strategies for extending and maintaining acute antidepressive responses to low-dose IV ketamine in patients with treatment-resistant unipolar or bipolar depression and provides some preliminary considerations for clinical practice.

Ketamine for depression clinical issues

Major depressive disorder (MDD) is a debilitating illness with significant morbidity and mortality, leading to attempted and completed suicides. It affects interpersonal relationships and also contributes to decreased productivity, causing financial burden to individuals and society. Patients often fail to respond to various antidepressant medication trials resulting in treatment-resistant depression (TRD). Current antidepressant medications work by modulating the monoaminergic systems and takes several weeks to establish a clinical response. Ketamine has been used extensively as an anesthetic agent since the 1970s, and more recent research has shown its rapid and robust effectiveness in TRD the subject of this review. Ketamine is a racemic mixture comprised of two enantiomers (R)-ketamine and (S)-ketamine and acts as an NMDA receptor antagonist. Most research studies have explored its antidepressant and antisuicidal effects by using it as an intravenous infusion or via the intranasal route due to increased bioavailability. Recently an intranasal esketamine spray was approved by the United States Food and Drug Administration (FDA) for TRD as an adjunct to standard antidepressant treatment in a supervised setting. Regarding its safety profile, multiple research studies have established the short-term safety and efficacy of ketamine in TRD. The cardiorespiratory and neuropsychiatric adverse events observed in these studies were mostly transient. However, ketamine is a scheduled agent with abuse potential, making its long-term use challenging and mandating further research.

Development of the Ketamine Side Effect Tool (KSET)

BACKGROUND

Currently, no specific, systematic assessment tool for the monitoring and reporting of ketamine-related side effects exists. Our aim was to develop a comprehensive Ketamine Side Effect Tool (KSET) to capture acute and longer-term side effects associated with repeated ketamine treatments.

METHODS

Informed by systematic review data and clinical research, we drafted a list of the most commonly reported side effects. Face and content validation were obtained via feedback from collaborators with expertise in psychiatry and anaesthetics, clinical trial piloting and a modified Delphi Technique involving ten international experts.

RESULTS

The final version consisted of four forms that collect information at time points: screening, baseline, immediately after a single treatment, and longer-term follow-up. Instructions were developed to guide users and promote consistent utilisation.

LIMITATIONS

Further evaluation of feasibility, construct validity and reliability is required, and is planned across multiple international sites.

CONCLUSIONS

The structured Ketamine Side Effect Tool (KSET) was developed, with confirmation of content and face validity via a Delphi consensus process. This tool is timely, given the paucity of data regarding ketamine's safety, tolerability and abuse potential over the longer term, and its recent adoption internationally as a clinical treatment for depression. Although based on data from depression studies, the KSET has potential applicability for ketamine (or derivatives) used in other medical disorders, including chronic pain. We recommend its utilisation for both research and clinical scenarios, including data registries.

Ascending-Dose Study of Controlled-Release Ketamine Tablets in Healthy Volunteers: Pharmacokinetics, Pharmacodynamics, Safety, and Tolerability

Parenteral ketamine has fast-onset antidepressant and antianxiety effects; however, it causes dissociation, hypertension, and tachycardia shortly after dosing. Ketamine's antidepressant effects may be due to active metabolites rather than to ketamine itself. We hypothesized that oral controlled-release ketamine tablets would improve safety and tolerability compared with injected ketamine by reducing peak ketamine exposures compared with dosing by injection. In this randomized, placebo-controlled ascending-dose study, ketamine doses of 60, 120, or 240 mg or matching placebo (single dose followed by every-12-hours dosing for 5 doses) were given to 24 healthy volunteers. Pharmacokinetics, pharmacodynamics (brain-derived neurotropic factor), adverse events, and vital signs were assessed up to 72 hours. Drug release occurred over ∼10 hours, with most drug substance present as norketamine (∼90%). Area under the concentration-time curve and peak concentration were dose proportional. Elimination half-life was prolonged (7-9 hours) compared with published data from immediate-release oral formulations. There were no changes in blood pressure or heart rate after any dose. Mild dissociation was reported after 240 mg but not lower doses; mean dissociation ratings in this group were minimal (1-2/76). There were no clinically significant changes in ECGs or safety laboratory tests at any time. Compared with injected ketamine, oral controlled-release ketamine tablets did not increase blood pressure or heart rate, and only at doses of 240 mg was dissociation of mild intensity reported. Reducing and delaying ketamine peak concentration by oral dosing with controlled-release ketamine tablets improve this drug's tolerability for patients with depression/anxiety.

Oral esketamine for treatment-resistant depression: rationale and design of a randomized controlled trial

BACKGROUND

There is an urgent need to develop additional treatment strategies for patients with treatment-resistant depression (TRD). The rapid but short-lived antidepressant effects of intravenous (IV) ketamine as a racemic mixture have been shown repeatedly in this population, but there is still a paucity of data on the efficacy and safety of (a) different routes of administration, and (b) ketamine's enantiomers esketamine and arketamine. Given practical advantages of oral over IV administration and pharmacodynamic arguments for better antidepressant efficacy of esketamine over arketamine, we designed a study to investigate repeated administration of oral esketamine in patients with TRD.

METHODS

This study features a triple-blind randomized placebo-controlled trial (RCT) comparing daily oral esketamine versus placebo as add-on to regular antidepressant medications for a period of 6 weeks, succeeded by a follow-up of 4 weeks. The methods support examination of the efficacy, safety, tolerability, mechanisms of action, and economic impact of oral esketamine in patients with TRD.

DISCUSSION

This is the first RCT investigating repeated oral esketamine administration in patients with TRD. If shown to be effective and tolerated, oral esketamine administration poses important advantages over IV administration.

TRIAL REGISTRATION

Dutch Trial Register, NTR6161. Registered 21 October 2016.

Stereoselective Ketamine Metabolism by Genetic Variants of Cytochrome P450 CYP2B6 and Cytochrome P450 Oxidoreductase

WHAT WE ALREADY KNOW ABOUT THIS TOPIC

WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Human ketamine N-demethylation to norketamine in vitro at therapeutic concentrations is catalyzed predominantly by the cytochrome P4502B6 isoform (CYP2B6). The CYP2B6 gene is highly polymorphic. CYP2B6.6, the protein encoded by the common variant allele CYP2B6*6, exhibits diminished ketamine metabolism in vitro compared with wild-type CYP2B6.1. The gene for cytochrome P450 oxidoreductase (POR), an obligatory P450 coenzyme, is also polymorphic. This investigation evaluated ketamine metabolism by genetic variants of human CYP2B6 and POR.

METHODS

CYP2B6 (and variants), POR (and variants), and cytochrome b5 (wild-type) were coexpressed in a cell system. All CYP2B6 variants were expressed with wild-type POR and b5. All POR variants were expressed with wild-type CYP2B6.1 and b5. Metabolism of R- and S-ketamine enantiomers, and racemic RS-ketamine to norketamine enantiomers, was determined using stereoselective high-pressure liquid chromatography-mass spectrometry. Michaelis-Menten kinetic parameters were determined.

RESULTS

For ketamine enantiomers and racemate, metabolism (intrinsic clearance) was generally wild-type CYP2B6.1 > CYP2B6.4 > CYP2B6.26, CYP2B6.19, CYP2B6.17, CYP2B6.6 > CYP2B6.5, CYP2B6.7 > CYP2B6.9. CYP2B6.16 and CYP2B6.18 were essentially inactive. Activity of several CYP2B6 variants was less than half that of CYP2B6.1. CYP2B6.9 was 15 to 35% that of CYP2B6.1. The order of metabolism was wild-type POR.1 > POR.28, P228L > POR.5. CYP2B6 variants had more influence than POR variants on ketamine metabolism. Neither CYP2B6 nor POR variants affected the stereoselectivity of ketamine metabolism (S > R).

CONCLUSIONS

Genetic variants of CYP2B6 and P450 oxidoreductase have diminished ketamine N-demethylation activity, without affecting the stereoselectivity of metabolism. These results suggest candidate genetic polymorphisms of CYP2B6 and P450 oxidoreductase for clinical evaluation to assess consequences for ketamine pharmacokinetics, elimination, bioactivation, and therapeutic effects.

[Ketamine in the therapy of chronic pain and depression]

Although ketamine has been known and clinically applied for a long time, questions still arise around the many possible indications in which the anesthetic and analgesic substance could be used. In particular, these questions relate to new indications in which ketamine is used in low subanesthetic doses.The mechanism of action at the NMDA receptor clearly distinguishes ketamine from all other analgesics. Possible applications include the prevention of chronic postoperative pain as well as the treatment of neuropathic pain. With the treatment of refractory depression completely new therapeutic areas for ketamine could be established.

Halogen Substitution Influences Ketamine Metabolism by Cytochrome P450 2B6: In Vitro and Computational Approaches

Ketamine is analgesic at anesthetic and subanesthetic doses, and it has been used recently to treat depression. Biotransformation mediates ketamine effects, influencing both systemic elimination and bioactivation. CYP2B6 is the major catalyst of hepatic ketamine N-demethylation and metabolism at clinically relevant concentrations. Numerous CYP2B6 substrates contain halogens. CYP2B6 readily forms halogen-protein (particularly Cl-π) bonds, which influence substrate selectivity and active site orientation. Ketamine is chlorinated, but little is known about the metabolism of halogenated analogs. This investigation evaluated halogen substitution effects on CYP2B6-catalyzed ketamine analogs N-demethylation in vitro and modeled interactions with CYP2B6 using various computational approaches. Ortho phenyl ring halogen substituent changes caused substantial (18-fold) differences in Km, on the order of Br (bromoketamine, 10 μM) < Cl < F < H (deschloroketamine, 184 μM). In contrast, Vmax varied minimally (83-103 pmol/min/pmol CYP). Thus, apparent substrate binding affinity was the major consequence of halogen substitution and the major determinant of N-demethylation. Docking poses of ketamine and analogs were similar, sharing a π-stack with F297. Libdock scores were deschloroketamine < bromoketamine < ketamine < fluoroketamine. A Bayesian log Km model generated with Assay Central had a ROC of 0.86. The probability of activity at 15 μM for ketamine and analogs was predicted with this model. Deschloroketamine scores corresponded to the experimental Km, but the model was unable to predict activity with fluoroketamine. The binding pocket of CYP2B6 also suggested a hydrophobic component to substrate docking, on the basis of a strong linear correlation ( R2 = 0.92) between lipophilicity ( Alog P) and metabolism (log Km) of ketamine and analogs. This property may be the simplest design criteria to use when considering similar compounds and CYP2B6 affinity.

Repeated oral ketamine for out-patient treatment of resistant depression: randomised, double-blind, placebo-controlled, proof-of-concept study

BACKGROUND

Ketamine has been demonstrated to improve depressive symptoms.AimsEvaluation of efficacy, safety and feasibility of repeated oral ketamine for out-patients with treatment-resistant depression (TRD).

METHOD

In a randomised, double-blind, placebo-controlled, proof-of-concept trial, 41 participants received either 1 mg/kg oral ketamine or placebo thrice weekly for 21 days (ClinicalTrials.gov Identifier: NCT02037503). Evaluation was performed at baseline, 40 and 240 min post administration and on days 3, 7, 14 and 21. The main outcome measure was change in Montgomery-Åsberg Depression Rating Scale (MADRS).

RESULTS

Twenty-two participants were randomised to the ketamine group, and 19 to the control, with 82.5% (n = 33) completing the study. In the ketamine group, a decrease in depressive symptoms was evident at all time points, whereas in the control group a decrease was evident only 40 min post administration. The reduction in MADRS score on day 21 was 12.75 in the ketamine group versus 2.49 points with placebo (P &lt; 0.001). Six participants in the ketamine group (27.3%) achieved remission compared with none of the controls (P &lt; 0.05). The number needed to treat for remission was 3.7. Side-effects were mild and transient.

CONCLUSIONS

Repeated oral ketamine produced rapid and persistent amelioration of depressive symptoms in out-patients with TRD, and was well tolerated. These results suggest that add-on oral ketamine may hold significant promise in the care of patients suffering from TRD in the community.Declaration of interestNone.

Does oral administration of ketamine accelerate response to treatment in major depressive disorder? Results of a double-blind controlled trial

BACKGROUND

Major depressive disorder (MDD) exerts a high health and financial burden on society. The conventional pharmacotherapies for MDD are partially effective and the response to medication often starts with some delay. There are recent reports of antidepressant effects for oral ketamine.

METHODS

We employed a double-blind controlled trial to examine the time course of the therapeutic effect of ketamine when combined with the conventional administration of sertraline. A total of 81 patients participated in the study and were scored with the Hamilton Depression Rating Scale (HDRS) at baseline and at 2, 4 and 6 weeks after the start of the trial RESULTS: General linear model repeated measures demonstrated significant effect for time × treatment interaction on the HDRS scores, with significant difference at all time points post treatment. Early improvement was significantly greater in the ketamine group (85.4%) compared to the placebo group (42.5%). We did not observe any side effects for ketamine administration.

LIMITATIONS

Our follow up was limited to 6 weeks post initiation of treatment and cannot reveal the potential long-term adverse effects of oral ketamine and the sustainability of its benefit.

CONCLUSION

Altogether, our results suggest that oral ketamine may be considered as suitable adjuvant to sertraline in relieving depressive symptoms.

Consensus Guidelines on the Use of Intravenous Ketamine Infusions for Chronic Pain From the American Society of Regional Anesthesia and Pain Medicine, the American Academy of Pain Medicine, and the American Society of Anesthesiologists

BACKGROUND

Over the past 2 decades, the use of intravenous ketamine infusions as a treatment for chronic pain has increased dramatically, with wide variation in patient selection, dosing, and monitoring. This has led to a chorus of calls from various sources for the development of consensus guidelines.

METHODS

In November 2016, the charge for developing consensus guidelines was approved by the boards of directors of the American Society of Regional Anesthesia and Pain Medicine and, shortly thereafter, the American Academy of Pain Medicine. In late 2017, the completed document was sent to the American Society of Anesthesiologists' Committees on Pain Medicine and Standards and Practice Parameters, after which additional modifications were made. Panel members were selected by the committee chair and both boards of directors based on their expertise in evaluating clinical trials, past research experience, and clinical experience in developing protocols and treating patients with ketamine. Questions were developed and refined by the committee, and the groups responsible for addressing each question consisted of modules composed of 3 to 5 panel members in addition to the committee chair. Once a preliminary consensus was achieved, sections were sent to the entire panel, and further revisions were made. In addition to consensus guidelines, a comprehensive narrative review was performed, which formed part of the basis for guidelines.

RESULTS

Guidelines were prepared for the following areas: indications; contraindications; whether there was evidence for a dose-response relationship, or a minimum or therapeutic dose range; whether oral ketamine or another N-methyl-D-aspartate receptor antagonist was a reasonable treatment option as a follow-up to infusions; preinfusion testing requirements; settings and personnel necessary to administer and monitor treatment; the use of preemptive and rescue medications to address adverse effects; and what constitutes a positive treatment response. The group was able to reach consensus on all questions.

CONCLUSIONS

Evidence supports the use of ketamine for chronic pain, but the level of evidence varies by condition and dose range. Most studies evaluating the efficacy of ketamine were small and uncontrolled and were either unblinded or ineffectively blinded. Adverse effects were few and the rate of serious adverse effects was similar to placebo in most studies, with higher dosages and more frequent infusions associated with greater risks. Larger studies, evaluating a wider variety of conditions, are needed to better quantify efficacy, improve patient selection, refine the therapeutic dose range, determine the effectiveness of nonintravenous ketamine alternatives, and develop a greater understanding of the long-term risks of repeated treatments.

Can we increase the speed and efficacy of antidepressant treatments? Part II. Glutamatergic and RNA interference strategies

In the second part we focus on two treatment strategies that may overcome the main limitations of current antidepressant drugs. First, we review the experimental and clinical evidence supporting the use of glutamatergic drugs as fast-acting antidepressants. Secondly, we review the involvement of microRNAs (miRNAs) in the pathophysiology of major depressive disorder (MDD) and the use of small RNAs (e.g.., small interfering RNAs or siRNAs) to knockdown genes in monoaminergic and non-monoaminergic neurons and induce antidepressant-like responses in experimental animals. The development of glutamatergic agents is a promising venue for antidepressant drug development, given the antidepressant properties of the non-competitive NMDA receptor antagonist ketamine. Its unique properties appear to result from the activation of AMPA receptors by a metabolite [(2S,6S;2R,6R)-hydroxynorketamine (HNK)] and mTOR signaling. These effects increase synaptogenesis in prefrontal cortical pyramidal neurons and enhance serotonergic neurotransmission via descending inputs to the raphe nuclei. This view is supported by the cancellation of ketamine's antidepressant-like effects by inhibition of serotonin synthesis. We also review existing evidence supporting the involvement of miRNAs in MDD and the preclinical use of RNA interference (RNAi) strategies to target genes involved in antidepressant response. Many miRNAs have been associated to MDD, some of which e.g., miR-135 targets genes involved in antidepressant actions. Likewise, SSRI-conjugated siRNA evokes faster and/or more effective antidepressant-like responses. Intranasal application of sertraline-conjugated siRNAs directed to 5-HT_1A receptors and SERT evoked much faster changes of pre- and postsynaptic antidepressant markers than those produced by fluoxetine.

Perioperative pain management: an update for obstetrician-gynecologists

The opioid epidemic in the United States is unprecedented and continues to worsen. Many opioid abusers obtain their pills through legitimate prescriptions, directly or indirectly, from a medical provider. While practitioners have a responsibility to treat pain, it is now becoming clear that aggressive opioid prescription practices contribute to an epidemic of abuse. The medical community has to balance the unintended consequences of opioid misuse and abuse with the need to provide adequate pain control. Additionally, providers are being held accountable by the legal system and professional organizations for their prescribing practices. Responsible use of opioids is paramount and pain control does not supersede safety. Effective and safe pain management requires that providers perform risk assessments, understand medication risks, avoid excessive reliance on opioids, and adequately monitor and educate patients. Obstetricians and gynecologists are uniquely positioned to influence pain management practices as primary care providers and surgeons who regularly manage both acute and chronic pain conditions. Therefore, the objective of this publication was to familiarize obstetricians and gynecologists with contemporary concepts in pain management and summarize recent guidelines in a manner that is applicable to our specialty. We focus on perioperative pain management, which is the time period immediately before, during, and after surgery. Topics reviewed include proper risk assessment to evaluate a patient's potential for poor pain control or development of chronic pain or misuse of opioids; multimodal pain management with nonpharmacological, nonopioid alternatives, safe opioid-use strategies; education and documentation; and special considerations for women, veterans, and lactation concerns.

Impact of oral ketamine augmentation on hospital admissions in treatment-resistant depression and PTSD: a retrospective study

RATIONALE

Depressive episodes are the leading cause of mental health-related hospital admissions in Australia, and 44% of those admitted have a previous history of hospitalisations for depression (Admitted patient mental health-related care: (Australian Institute of Health and Welfare Aust Hospital Stat 2011-12, 2013). Despite numerous available antidepressant treatments, many patients do not respond to conventional therapy, having what is called 'treatment resistance' (Fava Biol Psychiatry 53:649-659, 2003). In recent years, ketamine has risen to prominence as an effective, rapidly acting antidepressant (Ketamine: a light in the darkness: Paleos and Ross 28-33, 2013). However, customary intravenous (IV) and intramuscular (IM) routes of administration and relapse rates after cessation remain barriers to more widely adopted usage.

OBJECTIVES

This study represents the largest retrospective review of patients receiving long-term oral ketamine for treatment-resistant depression and post-traumatic stress disorder (PTSD). Our purpose was to examine the safety and efficacy of oral ketamine therapy in an outpatient setting as measured by changes in hospitalisation for psychiatric episodes.

METHODS

Hospital records of 37 patients who received oral ketamine treatment were reviewed to compare the number and duration of psychiatric hospital admissions before and after treatment. Records were also screened for adverse medical events and changes in ketamine dosage over time.

RESULTS

Following treatment, inpatient hospital days were reduced by 70%, and hospital admissions were reduced by 65%. The dose of ketamine patients required was stable over time with no evidence of tolerance building. There were no serious adverse events and no long-term negative effects associated with ketamine.

CONCLUSIONS

Oral ketamine offers a promising pharmacologic adjunct to depression treatment. It may offer a more approachable alternative to IV or IM ketamine. The results warrant further investigation into the safety and efficacy of oral ketamine for psychiatric treatment.

Ketamine treatment for depression: opportunities for clinical innovation and ethical foresight

We present a review and analysis of the ethical considerations in off-label ketamine use for severe, treatment-resistant depression. The analysis of ethical considerations is contextualised in an overview of the evidence for ketamine use in depression, and a review of the drug's safety profile. We find that, based on current evidence, ketamine use for severe, treatment-resistant depression does not violate ethical principles; however, clinicians and professional bodies must take steps to ensure that guidelines for good practice are enacted, that all experimental and trial data are made available through national registries, and that the risk potential of ketamine treatment continues to be monitored and modelled. We conclude with a set of key recommendations for oversight bodies that would support safe, effective, and ethical use of ketamine in depression.

Targeting glutamate signalling in depression: progress and prospects

Major depressive disorder (MDD) is severely disabling, and current treatments have limited efficacy. The glutamate N-methyl-D-aspartate receptor (NMDAR) antagonist ketamine was recently repurposed as a rapidly acting antidepressant, catalysing the vigorous investigation of glutamate-signalling modulators as novel therapeutic agents for depressive disorders. In this Review, we discuss the progress made in the development of such modulators for the treatment of depression, and examine recent preclinical and translational studies that have investigated the mechanisms of action of glutamate-targeting antidepressants. Fundamental questions remain regarding the future prospects of this line of drug development, including questions concerning safety and tolerability, efficacy, dose-response relationships and therapeutic mechanisms.

Administration of ketamine for unipolar and bipolar depression

OBJECTIVE

Clinical trials demonstrated that ketamine exhibits rapid antidepressant efficacy when administered in subanaesthetic dosages. We reviewed currently available literature investigating efficacy, response rates and safety profile.

METHODS

Twelve studies investigating unipolar, seven on bipolar depression were included after search in medline, scopus and web of science.

RESULTS

Randomized, placebo-controlled or open-label trials reported antidepressant response rates after 24 h on primary outcome measures at 61%. The average reduction of Hamilton Depression Rating Scale (HAM-D) was 10.9 points, Beck Depression Inventory (BDI) 15.7 points and Montgomery-Asberg Depression Rating Scale (MADRS) 20.8 points. Ketamine was always superior to placebo. Most common side effects were dizziness, blurred vision, restlessness, nausea/vomiting and headache, which were all reversible. Relapse rates ranged between 60% and 92%. To provide best practice-based information to patients, a consent-form for application and modification in local language is included.

CONCLUSIONS

Ketamine constitutes a novel, rapid and efficacious treatment option for patients suffering from treatment resistant depression and exhibits rapid and significant anti-suicidal effects. New administration routes might serve as alternative to intravenous regimes for potential usage in outpatient settings. However, long-term side effects are not known and short duration of antidepressant response need ways to prolong ketamine's efficacy.

New use for an old drug: oral ketamine for treatment-resistant depression

Treatment-resistant depression (TRD) is a disabling disorder that can interfere with a patient's capacity to understand and participate in medical care and thus negatively impact individual morbidity and mortality. Hospitalised patients with TRD may require rapid alleviation of severe symptomatology, particularly when suicidal or if unable to participate in care decisions. Ketamine is well known for its anaesthetic effects and its use as a 'street' drug; however, its action as an N-methyl-D-aspartate receptor antagonist makes ketamine a potential therapy for TRD. The majority of studies investigating ketamine for TRD have used intravenous drug delivery, demonstrating benefit for rapid alleviation and sustained response of depression symptoms. Oral ketamine for urgent alleviation of TRD symptoms is less reported. We describe rapid alleviation of severe TRD with oral ketamine in a severely ill postoperative hospitalised patient, and review the current literature on 'off-label' use of ketamine for treatment of refractory depression.

Ketamine: stimulating antidepressant treatment?

SUMMARY

The appeal of ketamine - in promptly ameliorating depressive symptoms even in those with non-response - has led to a dramatic increase in its off-label use. Initial promising results await robust corroboration and key questions remain, particularly concerning its long-term administration. It is, therefore, timely to review the opinions of mood disorder experts worldwide pertaining to ketamine's potential as an option for treating depression and provide a synthesis of perspectives - derived from evidence and clinical experience - and to consider strategies for future investigations.

DECLARATION OF INTERESTS

G.S.M. Grant/research support: National Health Medical Research Council, NSW Health, Ramsay Health, American Foundation for Suicide Prevention, AstraZeneca, Eli Lilly & Co, Organon, Pfizer, Servier, and Wyeth; has been a speaker for Abbott, AstraZeneca, Eli Lilly & Co, Janssen Cilag, Lundbeck, Pfizer, Ranbaxy, Servier, and Wyeth; consultant: AstraZeneca, Eli Lilly & Co, Janssen Cilag, Lundbeck, and Servier. M.A.F. Grant support: AssureRx, Janssen Research & Development, Mayo Foundation, Myriad, National Institute of Alcohol Abuse and Alcoholism (NIAAA), National Institute of Mental Health (NIMH), Pfizer. Consultant (Mayo): Janssen Research & Development, LLC, Mitsubishi Tanabe Pharma Corporation, Myriad Genetics, Neuralstem Inc., Sunovion, Supernus Pharmaceuticals, Teva Pharmaceuticals. CME/travel support: American Physician Institute, CME Outfitters. Financial interest/Mayo Clinic 2016: AssureRx. S.H.K. Grant/research support: Brain Canada, Bristol Meyer Squibb, CIHR, Janssen, Johnson & Johnson, Lundbeck, Ontario Brain Institute, Pfizer, Servier, St. Jude Medical, Sunovion. T.A.K. Grant/research support (through Stanford University): Sunovion Pharmaceuticals and Merck & Co., Inc.; consultant/advisory board bember: Allergan, Inc., Janssen Pharmaceuticals, Myriad Genetic Laboratories, Inc., and Sunovion Pharmaceuticals; lecture honoraria (not Speaker's Bureau payments): GlaxoSmithKline, and Sunovion Pharmaceuticals; royalties from American Psychiatric Publishing, Inc. Also, AstraZeneca Pharmaceuticals LP provided publication support to Parexel for preparation of a manuscript. Spouse employee and stockholder of Janssen Pharmaceuticals. R.W.L. Honoraria for speaking/advising/consulting, and/or received research funds: AstraZeneca, Brain Canada, Bristol Myers Squibb, Canadian Institutes of Health Research, Canadian Depression Research and Intervention Network, Canadian Network for Mood and Anxiety Treatments, Canadian Psychiatric Association, Coast Capital Savings, Johnson and Johnson, Lundbeck, Lundbeck Institute, Pfizer, Servier, St. Jude Medical, Takeda University, Health Network Foundation, and Vancouver Coastal Health Research Institute. R.M. Investigator Janssen trials of esketamine; 'paid-for' ketamine clinic operated by Oxford Health NHS Foundation Trust - fees used to support the Trust. M.J.O. Consultant: Sunovion and Acadia Pharmaceuticals. Full-time employee of U.S. Department of Veterans Affairs. M.E.T. Advisory/Consultant: Alkermes, Allergan, AstraZeneca, Bristol-Myers Squibb Company, Cerecor inc., Eli Lilly & Co., Forest Laboratories, Gerson Lehrman Group, Fabre-Kramer Pharmaceuticals, Inc., GlaxoSmithKline, Guidepoint Global, H. Lundbeck A/S, MedAvante Inc., Merck and Co. Inc. (formerly Schering Plough and Organon), Moksha8, Naurex Inc., Neuronetics Inc., Novartis, Ortho-McNeil Pharmaceuticals (Johnson & Johnson; Janssen), Otsuka, Pamlab, L.L.C. (Nestle), Pfizer (formerly Wyeth Ayerst Pharmaceuticals), Shire US Inc., Sunovion Pharmaceuticals Inc., Trius Therapeutical Inc. and Takeda. Grant support: Agency for Healthcare Research and Quality, Alkermes, AssureRx, Avanir, Forest Pharmaceuticals, Janssen, National Institute of Mental Health, and Otsuka Pharmaceuticals. Speakers Bureau: None since June, 2010. Equity Holdings: MedAvante, Inc. Royalties: American Psychiatric Foundation, Guilford Publications, Herald House, W.W. Norton & Company, Inc. Spouse's employment: Peloton Advantage, which does business with Pfizer. M.T. Full-time employee at Lilly 1997 to 2008. Honoraria/consulted: Abbott, AstraZeneca, Bristol Myers Squibb, GlaxoSmithKline, Lilly, Johnson & Johnson, Allergan, Otsuka, Merck, Sunovion, Forest, Geodon Richter Plc, Roche, Elan, Alkermes, Lundbeck, Teva, Pamlab, Minerva, Wyeth and Wiley Publishing. Spouse was full time-employee at Lilly 1998-2013.

COPYRIGHT AND USAGE

© The Royal College of Psychiatrists 2016. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) licence.

Antidepressant treatment response: 'I want it all, and I want it now!'†

The treatment of depression remains suboptimal, highlighting the need for more effective antidepressants. Traditional drug discovery and development is time-consuming and costly, prompting the need for faster translation of novel therapies into practice. But clinical expediency comes at a cost against which potential benefits need to be considered judiciously.