Ketamine-A Narrative Review of Its Uses in Medicine

Recurrent Serotonin Syndrome After Ketamine-assisted Electroconvulsive Therapy: A Case Report and Review of the Literature

Serotonin (5-HT) syndrome (SS) consists of changes in mental status as well as autonomic and neuromuscular changes. Though not well understood, serotonergic pathways have been implicated in the mechanism of action of electroconvulsive therapy (ECT). Ketamine has been used as an induction agent in ECT and as therapy for treatment-resistant depression. Utilizing a case report and literature review, we explored the underlying serotonergic mechanisms of ECT and ketamine by which a syndrome of serotonin toxicity may be precipitated. We describe the case of a 72-year-old woman who developed recurrent SS on 2 occasions in similar circumstances involving the administration of ketamine for ECT. In our literature review, we found 5 cases in which SS was associated with ECT and 1 case linking ketamine to SS. There is emerging evidence that the mechanism of ECT involves 5-HT1A and 5-HT2A receptors, the same receptors that are involved in SS. ECT can transiently increase the permeability of the blood-brain barrier, leading to increased levels of antidepressants in the brain. ECT can, therefore, enhance 5-HT transmission and the likelihood of SS in the presence of serotonergic agents. The effect of ketamine on 5-HT transmission is mediated by the glutamate α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor. Ketamine increases α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid activity in the medial prefrontal cortex, which leads to downstream 5-HT release through glutamate. Through this mechanism, ketamine can increase 5-HT transmission, leading to SS. To our knowledge, this is the only case report of recurrent SS with concurrent use of ECT and ketamine. As ketamine is frequently used in ECT and many patients undergoing ECT are on serotonergic medications, it is important to recognize ketamine as a potential risk factor for SS. There is no evidence for added efficacy when combining ECT and ketamine. Thus, one should proceed with caution when combining these treatments. The burgeoning use of ketamine in ambulatory settings makes it necessary to elucidate the risks, which we discuss further. More research is needed into the mechanisms of ketamine and ECT, specifically how the combination of these treatments influence 5-HT levels.

Perioperative Ketamine and Cancer Recurrence: A Comprehensive Review

Cancer is a significant global health threat and a leading cause of death worldwide. Effective early-stage interventions, particularly surgery, can potentially cure many solid tumors. However, the risk of postoperative cancer recurrence remains high. Recent research highlights the influence of perioperative anesthetic and analgesic choices on the fate of residual cancer cells, potentially affecting recurrence risks. Among these agents, ketamine-a well-known anesthetic and analgesic-has garnered interest due to its antitumor properties, mainly through inhibiting the N-methyl-D-aspartate (NMDA) receptor found in various cancer tissues. Additionally, ketamine's potential immunomodulatory effects, given the expression of NMDA receptors on immune cells, suggest that it plays a significant role during the perioperative period. This review synthesizes current evidence on ketamine's impact on cancer cell biology, inflammation, immune modulation, and the role of the gut microbiota, proposing ketamine as a promising agent for enhancing oncological outcomes.

Safety and tolerability of esketamine in propofol based sedation for endoscopic variceal ligation with or without injection sclerotherapy: Randomized controlled trial

OBJECTIVES

Esketamine is an S (+) enantiomer of ketamine with greater potency and similar psychomimetic effects compared to racemic ketamine. We aimed to explore the safety of esketamine in different doses as an adjuvant to propofol in patients undergoing endoscopic variceal ligation (EVL) with or without injection sclerotherapy.

METHODS

One hundred patients were randomized to receive sedation with propofol 1.5 mg/kg in combination with sufentanil 0.1 μg/kg (group S), esketamine 0.2 mg/kg (group E0.2), esketamine 0.3 mg/kg (group E0.3), or esketamine 0.4 mg/kg (group E0.4) for EVL (n = 25 each). Hemodynamic and respiratory parameters were recorded during the procedure. The primary outcome was the incidence of hypotension; secondary outcomes included the incidence of desaturation, positive and negative syndrome scale (PANSS) after the procedure, pain score after the procedure, and secretion volume.

RESULTS

The incidence of hypotension was significantly lower in groups E0.2 (36%), E0.3 (20%), and E0.4 (24%) than in group S (72%). The incidence of SpO2  ≤94% was significantly lower in group E0.4 (4%) than in group S (32%). No significant intergroup difference was found in the PANSS assessment.

CONCLUSIONS

Combining 0.4 mg/kg esketamine with propofol sedation was optimal to facilitate EVL with stable hemodynamic status and better respiratory function during the procedure, without significant psychomimetic side-effects.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (Trial ID: ChiCTR2100047033, http://www.chictr.org.cn/showproj.aspx?proj=127518).

Ketamine Evolving Clinical Roles and Potential Effects with Cognitive, Motor and Driving Ability

While driving under the influence of drugs, drivers are more likely to be involved in and cause more accidents than drivers who do not drive under the influence. Ketamine is derived from phencyclidine and acts as a noncompetitive antagonist and allosteric modulator of N-methyl-D-aspartate receptors. Ketamine has been used to treat a variety of psychiatric disorders, with the most notable being treatment-resistant depression. With the rise of at-home ketamine treatment companies, the safety of unsupervised administration remains under evaluation. A study with ketamine and a ketamine-like medication, rapasitnel, showed that those who were given ketamine experienced more sleepiness and had decreased self-reported motivation and confidence in their driving abilities. Moreover, there seem to be significant differences in the acute versus persistent effects of ketamine, as well as the anesthetic versus subanesthetic doses, both in terms of effects and outcomes. These divergent effects complicate the clinical uses of ketamine, specifically involving driving, drowsiness, and cognitive abilities. This review aims to describe not only the various clinical uses of ketamine but also the potentially detrimental effects of driving under the influence, which should be understood to help with counseling the patients who use these substances, both for their well-being and to protect public safety.

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.

Impact of Intraoperative Ketamine on Postoperative Analgesic Requirement Following Bariatric Surgery: a Meta-analysis of Randomized Controlled Trials

This meta-analysis aimed at exploring the impact of intravenous ketamine on pain relief and analgesic consumption in patients undergoing bariatric surgery (BS). Literature searches identified nine eligible trials with 458 participants. Forest plot revealed a significantly lower pain score [mean difference (MD) =  - 1.06, p = 0.005; 390 patients) and morphine consumption (MD =  - 3.85 mg, p = 0.01; 212 patients) immediately after BS in patients with intravenous ketamine than in those without. In contrast, pooled analysis showed comparable pain score (p = 0.28), morphine consumption (p = 0.45) within 24 h, and risk of postoperative nausea/vomiting (p = 0.67) between the two groups. In conclusion, the meta-analysis demonstrated improvements in pain outcomes immediately after surgery through perioperative intravenous ketamine administration despite the absence of analgesic benefit in the late postoperative period and a positive impact on postoperative nausea/vomiting.

Developing an IV Ketamine Clinic for Treatment-Resistant Depression: a Primer

The efficacy of subanesthetic intravenous ketamine for treatment resistant depression (TRD) has spurred a growth of clinics nationwide that provide this service. Ketamine is an FDA-approved drug as an anesthetic but remains unapproved for psychiatric indications, and this status raises a number of short- and long-term safety and efficacy concerns that need to be addressed when implementing and developing this type of clinic. Using a framework of systems, provider, and patient domains, we provide a review of the key challenges in providing ketamine infusions and suggest potential approaches. Under systems issues, we highlight broad stakeholder engagement involving cross-departmental and multidisciplinary considerations, business case development, and delineation of administrative standard operating procedures. In the provider domain, we highlight specific roles for different treatment team members as well as suggested training requirements. In the patient domain, we identify a variety of standard operating procedures involving initial patient assessment parameters, ketamine dosing and administration guidelines, and safety monitoring procedures. Together, this review provides key considerations for developing a ketamine clinic for depression, in an effort to meet the pressing demand for this novel treatment option while helping to ensure its safe implementation.

A review on the recent application of ketamine in management of anesthesia, pain, and health care

Ketamine is considered as a promising drug for many clinical applications even after five decades since its discovery. Ketamine is a dissociative anesthetic agent with a variety of pharmacological effects from anesthetic induction and maintenance to analgesic and sedative depending on the consuming dose. It can be used solely or in combination with other co-adjuvant drugs, increasing their efficacy. Many therapeutic properties of ketamine have been attributed to its antagonism mechanism to N-Methyl-D-aspartate receptor. Identifying new properties of ketamine such as neuroprotective, antiinflammatory, and antitumor effects, on one hand, and taking advantage of subanesthetic regimens of ketamine, on the other hand, have resulted in a widespread use of ketamine in various clinical applications. Ketamine is solvable in aqueous and lipid solutions, providing convenient administration via multiple routes, including oral, nasal, rectal, intravenous, intramuscular, subcutaneous, transdermal, sublingual, and intraosseous administration. Application of ketamine has some advantages over other sedative and anesthetic agents. It produces bronchodilation status, allowing for most secure induction of anesthesia in patients with life-threatening asthma and intense acute bronchial constriction. Ketamine has an excellent hemodynamic profile, makes it the agent of choice for patients with unstable hemodynamics, such as shocked or hypotensive patients. Ketamine usage has been associated with a lower risk of respiratory depression and relatively more conserved airway reflexes. Although being an anesthetic agent, ketamine has been increasingly used in subanesthetic doses for acute and chronic pain as well as depression. Using ketamine in pre and postoperative pain management is well established. However, the studies on ketamine performance in pain management demonstrated contradicting results. On the other hand, various side effects along with no confirmatory data on long-term treatment demand great caution when using ketamine for treating complex chronic pains. The present study aimed to provide a general review on the recent applications of ketamine in anesthesia, pain management, and critical care.

The effect of ketamine on emergence agitation in children: A systematic review and meta-analysis

BACKGROUND

Ketamine is believed to reduce the incidence of emergence agitation in children undergoing surgery or procedure. However, recent randomized controlled trials reported conflicting findings.

AIMS

To investigate the effect of ketamine on emergence agitation in children.

METHODS

Databases of MEDLINE, EMBASE, and CENTRAL were systematically searched from their start date until February 2019. Randomized controlled trials comparing intravenous ketamine and placebo in children were sought. The primary outcome was the incidence of emergence agitation. Secondary outcomes included postoperative pain score, duration of discharge time, and the adverse effects associated with the use of ketamine, namely postoperative nausea and vomiting, desaturation, and laryngospasm.

RESULTS

Thirteen studies (1125 patients) were included in the quantitative meta-analysis. The incidence of emergence agitation was 14.7% in the ketamine group and 33.3% in the placebo group. Children receiving ketamine had a lower incidence of emergence agitation, with an odds ratio being 0.23 (95% confidence interval: 0.11 to 0.46), certainty of evidence: low. In comparison with the placebo, ketamine group achieved a lower postoperative pain score (odds ratio: -2.42, 95% confidence interval: -4.23 to -0.62, certainty of evidence: very low) and lower pediatric anesthesia emergence delirium scale at 5 minutes after operation (odds ratio: -3.99, 95% confidence interval: -5.03 to -2.95; certainty of evidence: moderate). However, no evidence was observed in terms of incidence of postoperative nausea and vomiting, desaturation, and laryngospasm.

CONCLUSION

In this meta-analysis of 13 randomized controlled trials, high degree of heterogeneity and low certainty of evidence limit the recommendations of ketamine for the prevention of emergence agitation in children undergoing surgery or imaging procedures. However, the use of ketamine is well-tolerated without any notable adverse effects across all the included trials.

PROSPERO REGISTRATION

CRD42019131865.

Psychiatric Considerations Regarding Prehospital Administration of Ketamine for Agitation

Recently, ketamine has seen increased use among emergency medical services in the prehospital setting as a first-line means of chemical restraint for agitated patients. In this case report, we explore an instance in which ketamine administration for nonpsychotic agitation before emergency department (ED) evaluation may have caused unexpected psychotic symptoms leading to a complicated ED course necessitating admission. As ketamine gains widespread use in the prehospital setting, the safety profile deserves reevaluation. In the following report, we review relevant literature and discuss important factors to consider regarding the use of prehospital ketamine, including psychiatric and substance abuse history.

Semimechanistic Population Pharmacokinetic Model to Predict the Drug-Drug Interaction Between S-ketamine and Ticlopidine in Healthy Human Volunteers

Low‐dose oral S‐ketamine is increasingly used in chronic pain therapy, but extensive cytochrome P450 (CYP) mediated metabolism makes it prone to pharmacokinetic drug‐drug interactions (DDIs). In our study, concentration‐time data from five studies were used to develop a semimechanistic model that describes the ticlopidine‐mediated inhibition of S‐ketamine biotransformation. A mechanistic model was implemented to account for reversible and time‐dependent hepatic CYP2B6 inactivation by ticlopidine, which causes elevated S‐ketamine exposure in vivo. A pharmacokinetic model was developed with gut wall and hepatic clearances for S‐ketamine, its primary metabolite norketamine, and ticlopidine. Nonlinear mixed effects modeling approach was used (NONMEM version 7.3.0), and the final model was evaluated with visual predictive checks and the sampling‐importance‐resampling procedure. Our final model produces biologically plausible output and demonstrates that ticlopidine is a strong inhibitor of CYP2B6 mediated S‐ketamine metabolism. Simulations from our model may be used to evaluate chronic pain therapy with S‐ketamine.

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.

Diaphragm muscle activity across respiratory motor behaviors in awake and lightly anesthetized rats

Respiratory muscles such as the diaphragm are active across a range of behaviors including ventilation and higher-force behaviors necessary for maintenance of airway patency, and minimal information is available regarding anesthetic effects on the capacity of respiratory muscles to generate higher forces. The purpose of the present study was to determine whether diaphragm EMG activity during lower-force behaviors, such as eupnea and hypoxia-hypercapnia, is differentially affected compared with higher-force behaviors, such as a sigh, in lightly anesthetized animals. In adult male rats, chronically implanted diaphragm EMG electrodes were used to measure the effects of low-dose ketamine (30 mg/kg) and xylazine (3 mg/kg) on root mean square (RMS) EMG amplitude across a range of motor behaviors. A mixed linear model was used to evaluate the effects of ketamine-xylazine anesthesia on peak RMS EMG and ventilatory parameters, with condition (awake vs. anesthetized), behavior (eupnea, hypoxia-hypercapnia, sigh), side (left or right hemidiaphragm), and their interactions as fixed effects and animal as a random effect. Compared with the awake recordings, there was an overall reduction of peak diaphragm RMS EMG across behaviors during anesthesia, but this reduction was more pronounced during spontaneous sighs (which require ~60% of maximal diaphragm force). Respiratory rates and duty cycle during eupnea and hypoxia-hypercapnia were higher in awake compared with anesthetized conditions. These results highlight the importance of identifying anesthetic effects on a range of respiratory motor behaviors, including sighs necessary for maintaining airway patency. NEW & NOTEWORTHY Respiratory muscles accomplish a range of motor behaviors, with forces generated for ventilatory behaviors comprising only a small fraction of their maximal force generating capacity. Induction of anesthesia exerts more robust effects on the higher-force diaphragm motor behaviors such as sighs compared with eupnea. This novel information on effects of low, sedative doses of a commonly used anesthetic combination (ketamine-xylazine) highlights the importance of identifying anesthetic effects on a range of respiratory motor behaviors.

Glutamatergic agents for OCD and related disorders

Pharmacotherapy remains inadequate for many patients with OCD; there is an urgent need for alternative pharmacological strategies. Convergent evidence suggests imbalance in glutamate, the brain's primary excitatory neurotransmitter, in some patients. This has motivated interest in glutamate modulators in patients who are unresponsive to standard pharmacotherapeutic approaches. While no glutamate modulator can be considered proven as an efficacious treatment of OCD, promising suggestions of benefit have been reported for memantine and riluzole. The evidence is thinner for N-acetylcysteine, but this agent's low cost and benign side effect profile make it a reasonable consideration in certain patients. Intriguing research on D-cycloserine and ketamine suggest potential benefit as well. It is notable that these agents all work by different, and in some cases opposite, mechanisms; this suggests that we have much to learn about the role of glutamate dysregulation in the etiology of OCD, and of glutamate modulators in its treatment.