Maintenance Ketamine Therapy for Treatment-Resistant Depression

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.

Real-world depression, anxiety and safety outcomes of intramuscular ketamine treatment: a retrospective descriptive cohort study

BACKGROUND

Ketamine has emerged as a promising pharmacotherapy for depression and other mental illnesses, and the intramuscular (IM) administration of ketamine is now offered at many North American outpatient psychiatric clinics. However, a characterization of the outpatient population receiving IM ketamine treatment and an evaluation of the real-world depression, anxiety, and safety outcomes of long-term psychiatric IM ketamine treatment has not been reported. This study aimed to evaluate the clinical characteristics, treatment patterns, clinical outcomes, and adverse events of patients receiving IM ketamine treatment.

METHODS

Patient data from the electronic health records of a private outpatient psychiatric clinic network in the United States were collected and analyzed retrospectively. Adults with any psychiatric diagnosis who received ketamine treatment only by IM administration from January 2018 to June 2021 were included. A total of 452 patients were included in the cohort.

RESULTS

Patients receiving IM ketamine treatment had a mean of 2.8 (SD 1.4) psychiatric diagnoses. 420 (93%) patients had a diagnosis of major depressive disorder, 243 (54%) patients had a diagnosis of generalized anxiety disorder, and 126 (28%) patients had a diagnosis of post-traumatic stress disorder. Patients received a median of 4 (range 1-48) IM ketamine treatments. Median depression scores (PHQ-9) improved 38% from 16.0 (IQR 11.3-21.8) at baseline to 10.0 (IQR 6.0-15.0) at last treatment (p < .001). Median anxiety scores (GAD-7) improved 50% from 14.0 (IQR 8.0-17.0) at baseline to 7.0 (IQR 4.3-11.8) at last treatment (p < .001). With maintenance ketamine treatments, average improvements in depression (PHQ-9) and anxiety (GAD-7) scores of at least 4.7 and 4.9 points were maintained for over 7 months. An adverse event occurred during 59 of 2532 treatments (2.3%).

CONCLUSIONS

IM ketamine is being utilized to treat psychiatric outpatients with multiple mental illnesses not limited to depression. Average depression and anxiety levels significantly improve throughout IM ketamine treatment and do not regress to baseline during patients' maintenance treatment phase. Prospective studies are recommended to confirm the long-term effectiveness and safety of IM ketamine.

A retrospective analysis of ketamine intravenous therapy for depression in real-world care settings

BACKGROUND

Outcomes of ketamine intravenous therapy (KIT) for depression in real-world care settings have been minimally evaluated. We set out to quantify treatment response to KIT in a large sample of patients from community-based practices.

METHODS

We retrospectively analyzed 9016 depression patients who received KIT between 2016 and 2020 at one of 178 community practices across the United States. Depression symptoms were evaluated using the Patient Health Questionnaire-9 (PHQ-9). The induction phase of KIT was defined to be a series of 4-8 infusions administered over 7 to 28 days.

RESULTS

Among the 537 patients who underwent induction and had sufficient data, 53.6% of patients showed a response (≥ 50% reduction in PHQ-9 score) at 14-31 days post-induction and 28.9% remitted (PHQ-9 score drop to < 5). The effect size was d = 1.5. Among patients with baseline suicidal ideation (SI), 73.0% exhibited a reduction in SI. A subset (8.4%) of patients experienced an increase in depressive symptoms after induction while 6.0% of patients reported increased SI. The response rate was uniform across 4 levels of baseline depression severity. However, more severe illness was weakly correlated with a greater drop in scores while remission status was weakly inversely correlated with depression severity. Kaplan-Meier analyses showed that a patient who responds to KIT induction has approximately 80% probability of sustaining response at 4 weeks and approximately 60% probability at 8 weeks, even without maintenance infusions.

CONCLUSION

KIT can elicit a robust antidepressant response in community clinics; however, a small percentage of patients worsened.

Long-term outcomes of repeated ketamine infusions in patients with unipolar and bipolar depression: A naturalistic follow-up study

OBJECTIVE

Ketamine was proven to have short-term antidepressant effects. There is a paucity of studies focused on the long-term outcomes of repeated infusions of ketamine. This study aimed to examine the long-term outcomes of repeated ketamine infusions in patients with unipolar and bipolar depression METHODS: One hundred and eight patients with unipolar and bipolar depression completed the repeated treatment phase (administered ketamine three times weekly over a 12-day) and entered a 9-month naturalistic follow-up phase. Assessments were obtained at week 2, month 6, and month 9 after the repeated treatment phase. The Patient Health Questionnaire-9 (PHQ-9) Scale and the Global Assessment of Functioning (GAF) Scale were used to assess depressive symptoms and global functional status, respectively.

RESULTS

Seventy-one (65.7%) of patients completed the 9-month follow-up. On month 9, the response and remission rate were 80.3% and 78.9%, respectively. Among 56 patients who achieved response after the repeated treatment phase, 26 (46.4%) of patients sustained response during 9-month follow-up and their GAF score remained over 70. Sixteen patients relapsed during the 9-month follow-up and 14 (85.7%) of the relapse occurred during the first 2-week follow-up.

LIMITATION

The major limitation of this study is the open-label design.

CONCLUSIONS

This small sample study suggested that patients with unipolar and bipolar depression who response to repeated treatment with continued oral antidepressant may be a viable treatment option, and their global functional status improved with a follow-up. Relapse of depression tended to occur during the 2 weeks follow-up.

Non-parenteral Ketamine for Depression: A Practical Discussion on Addiction Potential and Recommendations for Judicious Prescribing

Intravenous (IV) ketamine is increasingly used off-label at subanesthetic doses for its rapid antidepressant effect, and intranasal (IN) esketamine has been recently approved in several countries for treating depression. The clinical utility of these treatments is limited by a paucity of publicly funded IV ketamine and IN esketamine programs and cost barriers to private treatment programs, as well as the drug cost for IN esketamine itself, which makes generic ketamine alternatives an attractive option. Though evidence is limited, use of non-parenteral racemic ketamine formulations (oral, sublingual, and IN) may offer more realistic access in less rigidly supervised settings, both for acute and maintenance treatment in select cases. However, the psychiatric literature has repeatedly cautioned on the addictive potential of ketamine and raised caution for both less supervised and longer-term use of ketamine. To date, these concerns have not been discussed in view of available evidence, nor have they been discussed within a broader clinical context. This paper examines the available relevant literature and suggests that ketamine misuse risks appear not dissimilar to those of other well-established and commonly prescribed agents with abuse potential, such as stimulants or benzodiazepines. As such, ketamine prescribing should be considered in a similar risk/benefit context to balance patient access and need for treatment with concern for potential substance misuse. Our consortium of mood disorder specialists with significant ketamine prescribing experience considers prescribing of non-parenteral ketamine a reasonable clinical treatment option in select cases of treatment-resistant depression. This paper outlines where this may be appropriate and makes practical recommendations for clinicians in judicious prescribing of non-parenteral ketamine.

Patterns and Predictors of Off-Label Drug Prescribing in Psychiatric Practice: A Qualitative Study

Off-label drug prescribing (OLDP) must be based on strong scientific evidence to make sure that patients get the optimum therapeutic outcomes. Adherence to the prerequisites is determined by the physicians’ attitude and knowledge. In this context, the present study was conducted with the goal of investigating psychiatrists’ perceptions of the use of OLDP in their clinical practice. A total of 14 psychiatrists were interviewed using a semi-structured interview guide. Thematic content analysis was performed. Data saturation was achieved at the 12th interview. Six major themes and fifteen subthemes emerged from qualitative interviews. Among the major themes were knowledge and concepts about the off-label drugs, attitude and current practice of prescribing off-label drugs, and rationale of prescribing and suggestions for reducing the use of off-label drugs. Almost all of the respondents interviewed provided detailed comments concerning the OLDP concept, depicted an optimistic approach and deemed that OLDP is quite common in psychiatry. Off-label usage of benzodiazepines such as clonazepam, diazepam and lorazepam in mania, depression, and obsessive–compulsive disorder were commonly reported. It was observed that the majority of the respondents did not inform the patients before prescribing off-label drugs. The present findings revealed that respondents had awareness; however, they depicted diverse attitudes towards prescribing off-label drugs. Further education and sensitization in regions with impoverished knowledge would certainly assist in preventing the risks associated with the use of OLDP.

Can Quetiapine Prolong the Antidepressant Effect of Ketamine?: A 5-Year Follow-up Study

PURPOSE

Ketamine, a noncompetitive, high-affinity antagonist of the N-methyl-d-aspartate-type glutamate receptor, has a rapid effect in patients with treatment-resistant disorder, but many patients who respond to intravenous ketamine relapse within several days. The objective of this study was to examine the long-term outcome of patients' mood 5 years after ketamine treatment.

METHODS

Sixteen electroconvulsive therapy referrals received at least 1 intravenous ketamine treatment in addition to their stable antidepressant medications. Depression was evaluated using the Inventory of Depressive Symptomatology-Clinician-Rated, Hamilton Rating Scales for Depression, and Montgomery-Åsberg Depression Rating Scale. Anxiety was measured using the Hamilton Rating Scale.

RESULTS

Of 16 patients treated, 6 achieved complete remission, 3 partially responded, and 7 did not respond. At baseline, all patients were treated with antidepressants, 14 patients were also treated with neuroleptics, of whom 5 patients were treated with quetiapine. The time to relapse in the 5 patients taking quetiapine was significantly longer than in patients who were taking other neuroleptics (965.83 ± 824.68 vs 80.5 ± 114.3, Z = 7.001, P = 0.0001). At the 5-year follow-up, 3 of the patients taking quetiapine maintained their remission. Overall levels of depression and anxiety at all times were improved in comparison to baseline.

CONCLUSIONS

Our follow-up results suggest that the combination of quetiapine and ketamine can prolong time to relapse after ketamine treatment in patients with treatment-resistant disorder.

Switching to Intranasal Esketamine Maintains the Antidepressant Response to Intravenous Racemic Ketamine Administration: A Case Series of 10 Patients

PURPOSE

This study aims to assess the efficacy and safety of intranasal (IN) esketamine as maintenance antidepressant therapy in patients who have demonstrated clinical improvement with off-label intravenous (IV) racemic ketamine for treatment-resistant depression (TRD).

METHODS

This is a retrospective case series of 10 consecutive outpatients with TRD who all had a clinically meaningful response when treated with IV racemic ketamine and were then switched to IN esketamine for maintenance therapy. Patient outcomes were assessed with the Montgomery-Åsberg Depression Rating Scale, Patient Health Questionnaire 9, and Clinical Global Impression of Improvement scale at each visit. Adverse effects were assessed at each treatment.

FINDINGS

Results indicated that 9 patients either maintained the benefit or showed greater improvement when transitioned to IN esketamine for antidepressant maintenance therapy. One patient had worsening of depression due to an acute psychosocial stressor but still improved from baseline IV racemic ketamine treatment. Six patients returned to work or pursued employment, and 4 patients with suicidal ideation remitted during IV racemic ketamine treatment and had no recurrence of suicidality with IN esketamine. No serious adverse reactions or tolerability issues were observed.

IMPLICATIONS

This case series reports the outcomes of 10 severely ill patients with TRD who had a clinically meaningful response to IV racemic ketamine and demonstrated a maintenance of effect or continued improvement when transitioned to IN esketamine. Although this finding needs to be replicated in larger, controlled studies, this report provides promising results for patients who have safely and effectively switched to Food and Drug Administration-approved IN esketamine after receiving acute or maintenance depression treatment with off-label IV racemic ketamine.

The Canadian Network for Mood and Anxiety Treatments (CANMAT) Task Force Recommendations for the Use of Racemic Ketamine in Adults with Major Depressive Disorder: Recommandations Du Groupe De Travail Du Réseau Canadien Pour Les Traitements De L'humeur Et De L'anxiété (Canmat) Concernant L'utilisation De La Kétamine Racémique Chez Les Adultes Souffrant De Trouble Dépressif Majeur

OBJECTIVE

Patients with major depressive disorder often have limited response to first-line and second-line medications; hence, novel pharmacological treatments are needed for treatment-resistant depression (TRD). Ketamine, an N-methyl-d-aspartate (NMDA) receptor antagonist, has demonstrated rapid antidepressant effects in patients with TRD. The Canadian Network for Mood and Anxiety Treatments (CANMAT) convened a task force to review the evidence for efficacy and safety of racemic ketamine and to provide recommendations for its use in clinical practice.

METHODS

A systematic review was conducted with computerized search of electronic databases up to January 31, 2020 using combinations of search terms, inspection of bibliographies, and review of other ketamine guidelines and consensus statements. The level of evidence and lines of treatment were assigned according to CANMAT criteria. Recommendations were given in question-answer format.

RESULTS

Intravenous (IV) racemic ketamine given as a single infusion has Level 1 evidence for efficacy in adults with TRD. The evidence for multiple infusions, given as an acute series or as ongoing maintenance treatment, is limited to Level 3. Adverse events associated with ketamine infusions include behavioral (e.g., dissociative symptoms) and physiological (e.g., hypertension) events. There is only Level 3 or 4 evidence for non-IV formulations of racemic ketamine. Consensus recommendations are given for clinical administration of IV ketamine including patient selection, facility and personnel issues, monitoring, and maintaining response.

CONCLUSIONS

Single-dose IV racemic ketamine is a third-line recommendation for adults with TRD. The need for repeated and maintenance ketamine infusions should be carefully assessed on a case-by-case basis with consideration of potential risks and benefits. Because of limited evidence for efficacy and risk for misuse and diversion, the use of oral and other formulations of racemic ketamine should be limited to specialists with ketamine-prescribing expertise and affiliations with tertiary or specialized centers.

[A review of the antidepressant properties of ketamine]

Major depression is a frequent and disabling disorder. Despite great developments in the field of psychopharmacology since the 1950's, delayed onset of action and treatment resistance to current pharmacological options, such as serotonin reuptake inhibitors, remain a therapeutic challenge. The recent discovery of the rapid antidepressant action of ketamine, an NMDA (N-methyl-D-aspartate) receptor antagonist, has brought a revolution to this field. This paper presents a comprehensive review of the clinical research on the antidepressant properties of ketamine as well as its presumed mechanisms of action.

Ketamine treatment for individuals with treatment-resistant depression: longitudinal qualitative interview study of patient experiences

BACKGROUND

Ketamine has recently received considerable attention regarding its antidepressant and anti-suicidal effects. Trials have generally focused on short-term effects of single intravenous infusions. Research on patient experiences is lacking.

AIMS

To investigate the experiences over time of individuals receiving ketamine treatment in a routine clinic, including impacts on mood and suicidality.

METHOD

Twelve fee-paying patients with treatment-resistant depression (6 females, 6 males, age 21-70 years; 11 reporting suicidality and 6 reporting self-harm) who were assessed as eligible for ketamine treatment participated in up to three semi-structured interviews: before treatment started, a few weeks into treatment and ≥2 months later. Data were analysed thematically.

RESULTS

Most participants hoped that ketamine would provide respite from their depression. Nearly all experienced improvement in mood following initial treatments, ranging from negligible to dramatic, and eight reported a reduction in suicidality. Improvements were transitory for most participants, although two experienced sustained consistent benefit and two had sustained but limited improvement. Some participants described hopelessness when treatment stopped working, paralleled by increased suicidal ideation for three participants. The transient nature and cost of treatment were problematic. Eleven participants experienced side-effects, which were significant for two participants. Suggestions for improving treatment included closer monitoring and adjunctive psychological therapy.

CONCLUSIONS

Ketamine treatment was generally experienced as effective in improving mood and reducing suicidal ideation in the short term, but the lack of longer-term benefit was challenging for participants, as was treatment cost. Informed consent procedures should refer to the possibilities of relapse and associated increased hopelessness and suicidality.

A systematic review and meta-analysis of the efficacy of intravenous ketamine infusion for treatment resistant depression: January 2009 - January 2019

BACKGROUND

Sub-anaesthetic administration of ketamine is an emerging practice in patients presenting treatment resistant depression (TRD), however several outstanding questions have yet to be answered.

OBJECTIVE

To evaluate the effect of intravenous ketamine infusion for patients presenting TRD on depression scores, clinical remission and response rates, and to assess its efficacy over both time and frequency.

METHODS

Five databases were searched up to January 4^th 2019 to include primary studies evaluating the use of sub-anaesthetic dose of ketamine in adults presenting TRD. Two reviewers independently performed the study selection, quality assessment and data extraction. Results were summarised in a narrative synthesis. A meta-analysis using a random effects model was performed when possible to examine changes in standardized mean differences and odds ratios of outcome measures at 4 hours, 24 hours, or 7 days post-infusion.

RESULTS

Twenty-eight studies in 35 publications were included. A strong ketamine effect was observed within 4 hours following a single infusion, and peaked at 24 hours. Ketamine's effectiveness was still present, yet somewhat diminished, 7 days post-infusion. Multiple infusions resulted in an enhanced and prolonged ketamine effect.

LIMITS

Due to insufficient data, long-term safety and efficacy of ketamine utilisation in patients presenting TRD are yet to be investigated.

CONCLUSIONS

Results provide support for the use of ketamine in the rapid management of depressive symptoms. While ketamine appears promising in the short-term treatment of TRD, more clinical and experimental data is needed with regards to the efficacy, tolerance and security of long-term administration of ketamine.

Long-term outcome in outpatients with depression treated with acute and maintenance intravenous ketamine: A retrospective chart review

BACKGROUND

Little is known about the long-term outcomes of repeated ketamine infusions for depression. We conducted a retrospective chart review to investigate outcomes of maintenance intravenous ketamine treatment at Massachusetts General Hospital.

METHODS

Eighty-five patients with treatment-resistant depression (TRD) who started intravenous ketamine from October 2018 to November 2019 were examined. Symptom severity was evaluated with the 16-item Quick Inventory of Depressive Symptomatology-Self Report scale (QIDS-SR₁₆) at every visit prior to administration. The initial ketamine dose was usually 0.5 mg/kg infused over 40 min. Intravenous ketamine was administered twice-weekly for three weeks in an induction phase, followed by maintenance with a variable administration schedule and dose. Response was defined as a ≥50% reduction in total QIDS-SR₁₆ score from baseline.

RESULTS

Forty (47.1%) of the 85 patients who started treatment discontinued during or right after the induction phase; 3 (3.5%) were still on induction at the time of this report, and 42 (49.4%) transitioned to maintenance after completing induction. Among these patients, 14 (16.5%) discontinued during maintenance and 28 (32.9%) continued on maintenance. The mean ketamine dosage during maintenance was 0.91±0.28 mg/kg. Fifteen out of 82 patients (18.3%) responded to induction treatment and 6 (7.3%) remained in responder status at the time of data analysis during maintenance. Three patients discontinued ketamine due to side-effects.

CONCLUSIONS

Despite the apparently low response rate in QIDS-SR₁₆ scores and considerable out-of-pocket costs, almost half of real-world outpatients with TRD decided to continue with maintenance ketamine treatment due to perceived significant improvement.

Lee K. Safety of Repeated Administration of Parenteral Ketamine for Depression

The objective of this study was to investigate the safety of repeated parenteral ketamine for depression. An electronic survey inquiring about the frequency of adverse events was distributed to providers of parenteral ketamine for depression. In addition, the investigators conducted a search of published studies describing six or more repeated parenteral ketamine treatments administered to individuals for depression, and extracted reported adverse events. The survey was sent to 69 providers, of which 36 responded (52% response rate); after eliminating those that were incomplete, 27 were included in the analysis. The providers in the analysis collectively reported treating 6630 patients with parenteral ketamine for depression, one-third of whom received more than 10 treatments. Only 0.7% of patients experienced an adverse effect that required discontinuation of ketamine. Psychological distress during the treatment was the most frequent cause. Other adverse events were extremely rare (such as bladder dysfunction (0.1%), cognitive decline (0.03%) and psychotic symptoms (0.03%)). Among the 20 published reports of repeated parenteral ketamine treatments, rates of significant adverse events resulting in discontinuation were low (1.2%). The rate of adverse effects reported in the survey and the published literature is low, and suggests that long-term treatment of depression with ketamine is reasonably safe.

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.

Psychedelics, but Not Ketamine, Produce Persistent Antidepressant-like Effects in a Rodent Experimental System for the Study of Depression

Psilocybin shows efficacy to alleviate depression in human clinical trials for six or more months after only one or two treatments. Another hallucinogenic drug, esketamine, has recently been U.S. Food and Drug Administration (FDA)-approved as a rapid-acting antidepressant. The mechanistic basis for the antidepressant effects of psilocybin and ketamine appear to be conserved. The efficacy of these two medications has not, however, been directly compared either clinically or preclinically. Further, whether or not a profound subjective existential experience is necessary for psilocybin to have antidepressant effects is unknown. To address these questions, we tested psilocybin, lysergic acid diethylamide (LSD), and ketamine in a rat model for depression. As in humans, a single administration of psilocybin or LSD produced persistent antidepressant-like effects in our model. In contrast, ketamine produced only a transient antidepressant-like effect. Our results indicate that classic psychedelics may have therapeutic efficacy that is more persistent than that of ketamine, and also suggest that a subjective existential experience may not be necessary for therapeutic effects.

Rapid and sustained improvement in treatment-refractory depression through use of acute intravenous ketamine and concurrent transdermal selegiline: A case series

BACKGROUND

Treatment resistant depression is a significant source of morbidity and mortality. For patients having failed or unable to undergo the electroconvulsive therapy procedure few effective alternative treatments exist.

METHODS

A case series is presented where six patients with treatment resistant depression failing both electroconvulsive therapy and oral antidepressants are concomitantly treated with short course intravenous ketamine and longer term selegiline transdermal system.

RESULTS

All six patients experienced clinical improvement with intravenous ketamine, with resolution of suicidality, increased food intake, and commitment to treatment adherence. Five patients showed sustained improvement with the selegiline transdermal system. One patient discontinued selegiline after developing peripheral edema and palpitations.

LIMITATIONS

This case series included only patients experiencing moderate to severe treatment resistant depression. Availability of long-term follow-up data not available in some cases.

CONCLUSION

Intravenous ketamine with simultaneous administration of the selegiline transdermal system is one strategy for treating treatment resistant depression in patients having failed or unable to undergo the electroconvulsive therapy procedure.

Esketamine for treatment resistant depression

Introduction: Treatment Resistant Depression (TRD) is a common and burdensome condition with poor outcomes and few treatment options. Esketamine is the S-enantiomer of ketamine and has recently been FDA approved in the United States for treating depression that has failed to respond to trials of two or more antidepressants. Areas covered: This review will briefly discuss current treatment options for TRD, then review esketamine. Relevant literature was identified through online database searches, and clinical trial data were provided by Janssen Pharmaceuticals. Pharmacology, including kinetics and dynamics, is discussed, then clinical data regarding efficacy and safety for esketamine from Phase 2-3 trials are reviewed. Expert opinion: In the expert opinion, the authors discuss multiple factors including patient, physician, and social factors that will influence the use of esketamine. While the efficacy of esketamine compared to off-label use of racemic ketamine remains unclear, both esketamine's approval for use in TRD and longer-term safety data may position it preferentially above racemic ketamine, although factors such as cost and monitoring requirements may limit its use. While questions remain regarding duration and frequency of treatment, as well as addictive potential, esketamine is a novel treatment option offering new hope for TRD.

Tachyphylaxis in major depressive disorder: A review of the current state of research

BACKGROUND

Patients with major depressive disorder (MDD) often experience a re-emergence or worsening of symptoms despite ongoing treatment with previously effective antidepressant pharmacotherapy. This lost or reduced antidepressant response during maintenance, referred to as tachyphylaxis, negatively impacts treatment outcomes and quality of life for patients with MDD. This review assesses the prevalence of antidepressant tachyphylaxis as well as the evidence for interventions to manage it.

METHODS

We searched PubMed/Medline for the relevant clinical trials and meta-analyses on antidepressant tachyphylaxis up to January 2017. Search terms included "depression" paired with "treatment" (n = 186,674), "tachyphylaxis" paired with "depression" (n = 112), "tachyphylaxis" paired with "major depressive disorder" (n = 21), and "antidepressant" paired with "tachyphylaxis" (n = 68). Studies were included if they reported on a clinical trial or meta-analysis exploring tachyphylaxis in MDD and were excluded if the sample population did not have a primary DSM diagnosis of MDD.

RESULTS

Rates of tachyphylaxis varied from 9% to 57% depending on the patient population and duration of follow-up. Limited evidence suggests potentially beneficial strategies for managing tachyphylaxis, including change in antidepressant dosing, switch of class of antidepressant medication, augmentation or combination pharmacotherapy, and psychotherapy.

LIMITATIONS

Studies of antidepressant tachyphylaxis are largely heterogeneous in nature and employ strict inclusion/exclusion criteria; thus, these findings may not be generalizable to all depressed populations.

CONCLUSION

Few established treatment strategies exist to manage antidepressant tachyphylaxis. Further interventional research is needed to provide symptomatic relief for patients with tachyphylaxis in MDD.