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.

Maintenance ketamine treatment for depression: a systematic review of efficacy, safety, and tolerability.

Ketamine has rapid yet often transient antidepressant effects in patients with treatment-resistant depression. Different strategies have been proposed to prolong these effects. Maintenance ketamine treatment appears promising, but little is known about its efficacy, safety, and tolerability in depression. We searched Pubmed, Embase, and the Cochrane Library and identified three randomised controlled trials, eight open-label trials, and 30 case series and reports on maintenance ketamine treatment. We found intravenous, intranasal, oral, and possibly intramuscular and subcutaneous maintenance ketamine treatment to be effective in sustaining antidepressant effect in treatment-resistant depression. Tachyphylaxis, cognitive impairment, addiction, and serious renal and urinary problems seem uncommon. Despite the methodological limitations, we conclude that from a clinical view, maintenance ketamine treatment seems to be of therapeutic potential. We recommend both controlled and naturalistic studies with long-term follow-up and sufficient power to determine the position of maintenance ketamine treatment within routine clinical practice.

Safety of Ketamine Augmentation to Monoamine Oxidase Inhibitors in Treatment-Resistant Depression: A Systematic Literature Review and Case Series.

Objective: Ketamine is increasingly prescribed for treatment-resistant depression (TRD), often as add-on to regular antidepressants. Augmentation of ketamine to monoamine oxidase inhibitors (MAOIs) is advised against, as this practice might increase blood pressure or cause serotonin syndrome. Despite the potential relevance for patients, little is known about actual side effects of combined use. We summarize literature on the safety and add results of our case series.Evidence Review: PubMed and Embase were searched from inception to July 2021 for English-language articles describing concomitant use of ketamine and MAOIs. The search strategy included terms for "ketamine" AND "monoamine oxidase inhibitor" including generic and brand names. Additionally, we describe the safety of twice weekly oral esketamine administration over the course of 5 weeks to 9 months in 8 TRD patients using MAOIs.Findings: After deduplication, we screened 138 articles and assessed 43 full texts. Twelve studies were included with a total of 39 patients receiving ketamine and MAOIs. Blood pressure and heart rate increased in multiple cases, though this was deemed clinically insignificant in all but 1 patient. No signs of hypertensive crisis or serotonin syndrome were observed. In our case series, we observed minor elevations in blood pressure and heart rate and no serious adverse events.Conclusions and Relevance: The results suggest that combined use of MAOIs and esketamine is less prone to severe side effects than presumed. The investigated sample size was small, and prescribed doses of MAOIs were relatively low. Further research is required before definite conclusions about the safety of this combination can be drawn.

The antidepressant effect and safety of non-intranasal esketamine: A systematic review.

BACKGROUND: The introduction of esketamine into the field of psychiatry comes on the heels of excitement from studies on racemic ketamine. While the intranasal route has been the most studied to date, other modes of administration of esketamine may also be of interest in the management of depression. AIMS: To systematically review the literature on non-intranasal esketamine for depression in terms of its antidepressant effect and safety. METHODS: We searched PubMed, Embase, the Cochrane Library, and Google Scholar from inception up to February 2021. Search terms included a combination of Medical Subject Headings and text words indicative of esketamine and depression. We selected both controlled and uncontrolled studies examining non-intranasal esketamine for the treatment of depression. RESULTS: We identified four randomized controlled trials (RCTs) on intravenous esketamine and 15 open-label studies on intravenous (n = 80), subcutaneous (n = 73), and oral (n = 5) esketamine. We found intravenous, subcutaneous, and possibly oral administration of esketamine to be effective in reducing depressive symptoms in most patients with major depressive disorder, bipolar depression, and (severe) treatment-resistant depression. Clinical response to repeated administration of esketamine persisted over the course of treatment. Esketamine was well tolerated by most patients, but open-label data indicate marked psychotomimetic symptoms in exceptional cases. The overall quality of the controlled studies was considered high, the overall quality of the uncontrolled studies low to moderate. CONCLUSIONS: Intravenous, subcutaneous, and possibly oral esketamine may offer an effective and safe addition to the depression treatment armamentarium. However, as most included studies lacked a control group and had small sample sizes, the quality of our results is limited. Different types and formulations of ketamine remain to be compared directly.

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.

Ketamine Treatment for Depression in Patients With a History of Psychosis or Current Psychotic Symptoms: A Systematic Review.

Objective: Ketamine shows rapid and robust antidepressant effects in clinical studies. Psychotic features are an exclusion criterion in most ketamine treatment studies based on the assumption that psychosis will increase with ketamine administration. As patients with treatment-resistant depression (TRD) often have psychotic features, and treatment-resistant depressive symptoms are also common in patients with schizophrenia, the aim of this systematic review is to determine whether this assumption holds true.Data Sources: The literature was searched for data on ketamine treatment for depression or negative symptomatology in patients with a history of psychosis or current psychotic symptoms (PubMed/MEDLINE) from inception to March 2020 without date or language restrictions. The following terms were used: ketamine and psychosis, psychotic or schizo*. A filter for human studies was applied.Study Selection: A total of 482 articles were identified; 473 articles were excluded because they did not report on the effect of ketamine treatment in patients with a history of psychosis or current psychotic symptoms.Data Extraction: The remaining 9 articles were reviewed.Results: Nine reports of pilot studies and case reports with a total of 41 patients have been published. These studies suggest that short-term ketamine treatment for depression and even negative symptoms in patients with a history of psychosis or current psychotic features can be both safe and effective, as side effects were mild and self-limiting.Conclusions: The currently available literature does not support the assumption that ketamine will exacerbate psychotic symptoms in predisposed patients. Data, however, are limited, and further trials are needed in this patient group.

Pharmacodynamic Interactions Between Ketamine and Psychiatric Medications Used in the Treatment of Depression: A Systematic Review.

BACKGROUND: The use of ketamine for depression has increased rapidly in the past decades. Ketamine is often prescribed as an add-on to other drugs used in psychiatric patients, but clear information on drug-drug interactions is lacking. With this review, we aim to provide an overview of the pharmacodynamic interactions between ketamine and mood stabilizers, benzodiazepines, monoamine oxidase-inhibitors, antipsychotics, and psychostimulants. METHODS: MEDLINE and Web of Science were searched. RESULTS: Twenty-four studies were included. For lithium, no significant interactions with ketamine were reported. Two out of 5 studies on lamotrigine indicated that the effects of ketamine were attenuated. Benzodiazepines were repeatedly shown to reduce the duration of ketamine's antidepressant effect. For the monoamine oxidase-inhibitor tranylcypromine, case reports showed no relevant changes in vital signs during concurrent S-ketamine use. One paper indicated an interaction between ketamine and haloperidol, 2 other studies did not. Four papers investigated risperidone, including 3 neuroimaging studies showing an attenuating effect of risperidone on ketamine-induced brain perfusion changes. Clozapine significantly blunted ketamine-induced positive symptoms in patients with schizophrenia but not in healthy participants. One paper reported no effect of olanzapine on ketamine's acute psychotomimetic effects. CONCLUSION: Current literature shows that benzodiazepines and probably lamotrigine reduce ketamine's treatment outcome, which should be taken into account when considering ketamine treatment. There is evidence for an interaction between ketamine and clozapine, haloperidol, and risperidone. Due to small sample sizes, different subject groups and various outcome parameters, the evidence is of low quality. More studies are needed to provide insight into pharmacodynamic interactions with ketamine.

Is ketamine an appropriate alternative to ECT for patients with treatment resistant depression? A systematic review.

OBJECTIVE: Ketamine has repeatedly shown to have rapid and robust antidepressant effects in patients with treatment resistant depression (TRD). An important question is whether ketamine is as effective and safe as the current gold standard electroconvulsive therapy (ECT). METHODS: The literature was searched for trials comparing ketamine treatment with ECT for depression in the Pubmed/MEDLINE database and Cochrane Trials Library. RESULTS: A total of 137 manuscripts were identified, 6 articles were included in this review. Overall quality of the included studies was diverse with relevant risk of bias for some of the studies. Results suggest that ketamine treatment might give faster but perhaps less durable antidepressant effects. Side effects differed from ECT, in particular less cognitive impairment was apparent in ketamine treatment. LIMITATIONS: The included studies have limited sample sizes, use different treatment protocols and in most trials, longer term follow up is lacking. Furthermore, allocation bias appears likely in the non-randomized trials. CONCLUSIONS: Current available literature does not yet provide convincing evidence to consider ketamine as an equally effective treatment alternative to ECT in patients with TRD. There are indications for a more favourable short term cognitive side effect profile after ketamine treatment. Methodologically well-designed studies with larger sample sizes and longer follow up duration are warranted.

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

After publication of our article [1] we were notified that Figure 1 was wrongly presented.

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.

Characteristics of patients expressing an interest in ketamine treatment: results of an online survey.

BACKGROUND: Off-label ketamine treatment has shown acute antidepressant effects that offer hope for patients with therapy-resistant depression. However, its potential for integration into treatment algorithms is controversial, not least because the evidence base for maintenance treatment with repeated ketamine administration is currently weak. Ketamine is also a drug of misuse, which has raised concerns regarding the target population. Little is known about which patients would seek ketamine treatment if it were more widely available. AIMS: To explore some of the characteristics of the patients actively seeking ketamine treatment. METHOD: An online survey containing questions about duration of current depressive episode, number of antidepressants used and other comments was completed by patients who were exploring the internet regarding the possibility of ketamine for depression. RESULTS: Of the 1088 people who registered their interest, 93.3% reported depression, 64.3% reported a chronic course of their symptoms and in the past 10 years, 86.3% had tried at least two antidepressants. Desperation was a common theme, but this appeared to be competently expressed. A small minority (<8%) reported experience of illegal ketamine use. CONCLUSIONS: It cannot be ruled out that patients with different degrees of treatment resistance and comorbidities will seek treatment with ketamine. This stresses the urgency to perform larger randomised controlled trials as well as to systematically monitor outcomes and adverse effects of ketamine, that is currently prescribed off-label for patients in need. DECLARATION OF INTEREST: R.M. is consulting and is Principal Investigator for Janssen trials of esketamine and is consulting for Eleusis.