Ketamine in chronic pain management: an evidence-based review

The effect of low dose intra-articular S(+) ketamine on osteoarthritis in rats: an experimental study

BACKGROUND

This study aimed to investigate the analgesic impact of S(+)-ketamine on pain behavior and synovial inflammation in an osteoarthritis (OA) model.

METHODS

Animals were grouped as follows: OA-Saline (n = 24) and OA-Ketamine (n = 24), OA induced via intra-articular sodium monoiodoacetate (MIA); a Non-OA group (n = 24) served as the control. On the 7th day post OA induction, animals received either saline or S(+)-ketamine (0.5 mg.kg-1). Behavioral and histopathological assessments were conducted up to day 28.

RESULTS

S(+)-ketamine reduced allodynia from day 7 to 28 and hyperalgesia from day 10 to 28. It notably alleviated weight distribution deficits from day 10 until the end of the study. Significant walking improvement was observed on day 14 in S(+)-ketamine-treated rats. Starting on day 14, OA groups showed grip force decline, which was countered by S(+)-ketamine on day 21. However, S(+)-ketamine did not diminish synovial inflammation.

CONCLUSION

Low Intra-articular (IA) doses of S(+)-ketamine reduced MIA-induced OA pain but did not reverse synovial histopathological changes.

IRB APPROVAL NUMBER

23115 012030/2009-05.

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.

The Use of Ketamine for Malignant and Nonmalignant Chronic Pain in Children: A Review of Current Evidence

Chronic pain in children continues to pose significant challenges. The pharmacological approach most often revolves around trials and errors, expert opinions, and extrapolation of adult study findings. Ketamine is one of the agents used for chronic pain, especially with a neuropathic component. This article aims to provide an overview of its properties and highlight the current evidence for its use in malignant and nonmalignant chronic pain management. A search on the use of ketamine for chronic pain in children up to 18 years of age covering the period from January 1, 2000, to December 14, 2022, was performed through PubMed, Cochrane Library, EBSCO, EBM Review, Wiley, BMJ, Web of Science, Google Scholar, and the Saudi Digital Library. 218 articles were found and 42 underwent full review. Currently, the evidence about ketamine efficacity and safety for chronic pain management is at best of moderate to low quality. The heterogeinity of ketamine infusion protocols and frequent concomitant use of other analgesics make it difficult to draw robust conclusions. The long-term effect of prolonged usage also remains a concern. Nevertheless, with careful monitoring, the drug may be a reasonable choice for malignant and nonmalignant pain management in selected cases, especially for refractory pain not responding to conventional approaches.

Ketamine-assisted psychotherapy treatment of chronic pain and comorbid depression: a pilot study of two approaches

Chronic pain and depression diagnoses are skyrocketing. There is an urgent need for more effective treatments. Ketamine was recently established to alleviate pain and depression, but many gaps remain in the scientific literature. This paper reports the findings of an observational preliminary study that explored the efficacy of ketamine-assisted psychotherapy (KAPT) for chronic pain/major depressive disorder (MDD) comorbidity. Researchers evaluated two KAPT approaches to determine optimal route of administration/dose. Ten individuals diagnosed with a chronic pain disorder and MDD receiving KAPT were recruited: five individuals pursuing the psychedelic approach (high doses administered intramuscularly 24 h before therapy) and five individuals pursuing the psycholytic approach (low doses administered sublingually via oral lozenges during therapy). To evaluate differences between altered states of consciousness each approach induces, participants completed the Mystical Experience Questionnaire (MEQ30) after their first (T-1), third (T-2) and sixth/final (T-3) treatment sessions. Primary outcomes were change in Beck Depression Inventory (BDI) scores and Brief Pain Inventory (BPI) Short Form scores from baseline (T0) to (T-1)-(T-3). Secondary outcomes were changes in Generalized Anxiety Disorder (GAD-7) Scale scores and Post-Traumatic Stress Disorder Checklist (PCL-5) scores at each timepoint. Statistically significant differences between each approach were not observed, but the small sample's limited statistical power makes changes seen worth noting. All participants' symptoms declined throughout treatment. Psychedelic treatment participants saw a larger, more consistent decrease. Researchers conclude that KAPT may be effective for treating chronic pain/MDD comorbidity, anxiety and Post-Traumatic Stress Disorder (PTSD). Findings imply that the psychedelic approach may be more effective. This pilot study serves as a basis for more extensive research that will inform how clinicians administer treatment to optimize outcomes.

Narrative Review: Low-Dose Ketamine for Pain Management

Pain is the leading cause of medical consultations and occurs in 50-70% of emergency department visits. To date, several drugs have been used to manage pain. The clinical use of ketamine began in the 1960s and it immediately emerged as a manageable and safe drug for sedation and anesthesia. The analgesic properties of this drug were first reported shortly after its use; however, its psychomimetic effects have limited its use in emergency departments. Owing to the misuse and abuse of opioids in some countries worldwide, ketamine has become a versatile tool for sedation and analgesia. In this narrative review, ketamine's role as an analgesic is discussed, with both known and new applications in various contexts (acute, chronic, and neuropathic pain), along with its strengths and weaknesses, especially in terms of psychomimetic, cardiovascular, and hepatic effects. Moreover, new scientific evidence has been reviewed on the use of additional drugs with ketamine, such as magnesium infusion for improving analgesia and clonidine for treating psychomimetic symptoms. Finally, this narrative review was refined by the experience of the Pain Group of the Italian Society of Emergency Medicine (SIMEU) in treating acute and chronic pain with acute manifestations in Italian Emergency Departments.

Advantages of ketamine in pediatric anesthesia

Although ketamine is primarily used for induction and maintenance of general anesthesia, it also presents sedative, amnestic, anesthetics, analgesic, antihyperalgesia, neuroprotective, anti-inflammatory, immunomodulant, and antidepressant effects. Its unique pharmacodynamics and pharmacokinetic properties allow the use of ketamine in various clinical settings including sedation, ambulatory anesthesia, and intensive care practices. It has also adopted to manage acute and chronic pain management. Clinically, ketamine produces dissociative sedation, analgesia, and amnesia while maintaining laryngeal reflexes, with respiratory and cardiovascular stability. Notably, it does not cause respiratory depression, maintaining both the hypercapnic reflex and the residual functional capacity with a moderate bronchodilation effect. In the pediatric population, ketamine can be administered through practically all routes, making it an advantageous drug for the sedation required setting such as placement of difficult vascular access and in uncooperative and oppositional children. Consequently, ketamine is indicated in prehospital induction of anesthesia, induction of anesthesia in potentially hemodynamic unstable patients, and in patients at risk of bronchospasm. Even more, ketamine does not increase intracranial pressure, and it can be safely used also in patients with traumatic brain injuries. This article is aimed to provide a brief and practical summary of the role of ketamine in the pediatric field.

Efficacy and Safety of Ketamine in the Treatment of Neuropathic Pain: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Purpose

Ketamine is a N-methyl-D-aspartate (NMDA) antagonist with strong analgesic properties. Its addition to the treatment of neuropathic pain may reduce pain intensity and improve overall quality of life. A systematic review and meta-analysis of randomized controlled trials was performed to investigate the addition of ketamine to the treatment of patients with neuropathic pain.

Patients and Methods

GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach was used to rate the overall certainty of the evidence for each outcome. Eighteen (18) randomized controlled trials including 706 participants were included for further analysis.

Results

Ketamine addition to standard treatment of neuropathic pain (NP) resulted in a statistically significant reduction of pain intensity at one week after the end of treatment with ketamine (MD −2.14, 95% CI −2.65 to −1.63; p<0.00001) and after 30 days after the end of treatment with ketamine (MD −1.68, 95% CI −2.25 to −1.12; p<0.00001) and a statistically significant increase in discomfort (RR 4.06; 95% CI 1.18 to 13.95; p=0.03), and psychedelic effects (RR 4.94; 95% CI 2.76 to 8.84; p<0.00001).

Conclusion

There is a statistically significant pain reduction by adding ketamine to the treatment of chronic NP when compared to the standard treatment. However, such pain reduction comes at the expense of adverse outcomes, especially psychedelic effects related to the administration of ketamine. However, the overall quality of certainty of evidence is low due to the clinical heterogeneity among the intervention characteristics of the trials analyzed (different administration routes, dosing regimen, therapy durations, different clinical characteristics of the population investigated). Future large multi-centered trials are necessary to confirm or not the results of the present review.

Management of Ketamine Extravasation in a Pediatric Patient During Procedural Sedation

Ketamine is a commonly used intravenous and intramuscular medication for procedural sedation within pediatric emergency medicine. There is limited availability of data on the rate of absorption and use of subcutaneous ketamine administration. We describe the case of a 12-year-old male who was sedated after extravasation and subsequent absorption of ketamine 1 mg/kg from a peripheral intravenous line (PIV). Despite being an unintended route, absorption of subcutaneous ketamine resulted in satisfactory procedural sedation with no complications. Given limited data on subcutaneous ketamine pharmacokinetics, the aim of this case report is to present the observed absorption of subcutaneous ketamine due to extravasation of PIV during a pediatric procedural sedation.

Ketamine therapy for chronic pain in The Netherlands: a nationwide survey

OBJECTIVES

Ketamine is used to treat chronic refractory pain. However, there are no scientific guidelines for ketamine use in the Netherlands. The aim of this survey was to provide an overview of the use of ketamine for chronic pain in the Netherlands.

METHODS

All pain clinics in the Netherlands were contacted. A digital survey, available from June 2019 to January 2020, was sent to 68 pain clinics. The survey was completed by one pain physician as a representative of the entire pain department. The survey included questions about ketamine treatment indications, administration, dose, duration, treatment repetition and the inpatient or outpatient setting.

RESULTS

The survey was completed by 51 pain clinics (75.0%). Thirty-one clinics used ketamine for chronic pain treatment. The most common indication was Complex Regional Pain Syndrome (83.9%). Pain clinics administered ketamine via intravenous infusions (96.8%), iontophoresis (61.3%), subcutaneous (3.2%) or oral administration (3.2%). Intravenous ketamine treatment was offered in an inpatient setting in 14 pain clinics, in both an inpatient and outpatient setting in 11 pain clinics and in six pain clinics in an outpatient setting. In the outpatient setting, the median starting dose was 5 mg/h (IQR=17.5-5). The median maximum dose was 27.5 mg/h (IQR=100-11.9). The median infusion duration was 6 h (IQR=8-4). In the inpatient setting, the median starting dose was 5 mg/h (IQR=5-1.5) and the median maximum dose was 25 mg/h (IQR=25-14). Patients were admitted to hospital for a median of 4 days (IQR=5-1).

CONCLUSIONS

The results of this Dutch nationwide survey study show that there are heterogeneous treatment protocols with different indications, treatment setting and dosing regimen for the treatment of chronic pain with ketamine. This study encourages the formulation of a broader consensus and the development of evidence based guidelines for ketamine treatment.

Repeated or Continuous Medically Supervised Ketamine Administration Associated with Hepatobiliary Adverse Events: A Retrospective Case Series

Introduction

Emerging off-label medical uses of ketamine for the treatment of persistent conditions such as depression and chronic pain often require repeated administration. Cases reported by other countries suggest that long-term and repeated exposure to ketamine may be associated with several risks, including but not limited to hepatobiliary damage.

Objective

We aimed (1) to characterize the association between repeated administration of ketamine for off-label medical use and hepatobiliary events and (2) to describe recent trends in the use of ketamine across different clinical settings.

Methods

We conducted a retrospective case series analysis, utilizing reports identified from the US Food and Drug Administration Adverse Event Reporting System database as well as the medical literature. We included all cases reported through July 2018 describing both repeated exposure to ketamine in a hospital or ambulatory setting and a hepatobiliary adverse event. We excluded cases describing ketamine abuse. We identified adverse hepatobiliary events using the Medical Dictionary for Regulatory Activities (MedDRA^®) and summarized various case characteristics including: patient demographics, route of ketamine administration, dose, time to onset of event, type of event, and pre-existing risk factors for hepatobiliary disease. To assess trends in the demand for ketamine, we used IQVIA, National Sales Perspectives™ to provide the nationally estimated number of vials sold for ketamine from the manufacturer to all US channels of distribution from 2013 through 2017.

Results

We identified 14 unique cases that met selection criteria with 21 hepatobiliary adverse events including liver enzyme elevation in all cases, biliary dilation with liver cirrhosis (n = 1), biliary dilation with cholangitis (n = 1), and pericholeductal fibrosis (n = 1). Most cases received ketamine for the treatment of complex regional pain syndrome or chronic pain. In cases with a reported time to onset, the majority of events occurred within 4 days. The nationally estimated number of ketamine vials sold in the USA from manufacturers to various channels of distribution increased from 1.2 million in 2013 to 2.1 million in 2017.

Conclusions

We report an association between repeated or continuous administration of ketamine and hepatobiliary adverse events. Increased awareness among clinicians may mitigate these adverse outcomes, especially in the context of growing ketamine sales.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40264-021-01120-9.

Long Term Safety and Efficacy of Sub-Lingual Ketamine Troches / Lozenges in Chronic Non-Malignant Pain Management

INTRODUCTION

Chronic non-malignant pain is a disabling condition that results in a reduction in function and quality of life when inadequately managed. Sub-lingual ketamine has been shown to be efficacious for use in chronic pain. Despite its use for decades in chronic non-malignant pain, there is no published long-term data on safety, side effects or adverse drug reactions. The aim of this case-series is to provide the initial evidence for safety and efficacy in this patient group.

METHODS

We present a retrospective review of twenty-nine patients (n=29) from a metropolitan tertiary pain service who have been receiving sub-lingual ketamine troches / lozenges between the period of 2012-2019. Patients were identified from the outpatient pain clinic, who had been admitted for inpatient subcutaneous ketamine infusions as part of opiate detoxification or management of central sensitisation due to a chronic neuropathic pain syndrome. An initial review was performed to check the patient started taking the ketamine troches. Each of these medical records was reviewed manually to extract information to a datasheet.

RESULTS

There was a wide range of dosages used from 25-600mg in divided doses. The duration of treatment ranged from 2-89 months. There was no association with either the dosage or duration of treatment and frequency of side effects. There was an overall reduction in the use of opioids, gabapentinoids or benzodiazepines in 59% of patients with 39% having a complete cessation of an analgesic agent. Side effects were reported in 24%, but only 7% discontinued the treatment due to the side effect (drowsiness). There were no reports of renal impairment, cystitis, or hepatotoxicity.

DISCUSSION

This retrospective case-series has demonstrated that sub-lingual ketamine is a safe and effective analgesic agent to use in chronic non-malignant pain management. It is indicated in a variety of chronic pain conditions and has an excellent safety profile, with no association between the frequency in side effects and duration of therapy or total daily dosages. The study has also shown that the "safe" dose may be higher than the previous consensus.

CONTRIBUTION STATEMENT

A.A and S.G. recruited the patients. A.A. & B.M. created the parameters for the data collection sheet. B.M Collected most of the data from the medical records, entered it into a datasheet, wrote the manuscript, ran the statistics, performed the data analysis, and generated the figures and tables. A.A. Edited the manuscript. S.G. and A.A were the research supervisors. This article is protected by copyright. All rights reserved.

Regional Techniques and Interventions for Intractable Neuropathic Pain

Collapse

A Central Amygdala-Ventrolateral Periaqueductal Gray Matter Pathway for Pain in a Mouse Model of Depression-like Behavior

BACKGROUND

The mechanisms underlying depression-associated pain remain poorly understood. Using a mouse model of depression, the authors hypothesized that the central amygdala-periaqueductal gray circuitry is involved in pathologic nociception associated with depressive states.

METHODS

The authors used chronic restraint stress to create a mouse model of nociception with depressive-like behaviors. They then used retrograde tracing strategies to dissect the pathway from the central nucleus of the amygdala to the ventrolateral periaqueductal gray. The authors performed optogenetic and chemogenetic experiments to manipulate the activity of this pathway to explore its roles for nociception.

RESULTS

The authors found that γ-aminobutyric acid-mediated (GABAergic) neurons from the central amygdala project onto GABAergic neurons of the ventrolateral periaqueductal gray, which, in turn, locally innervate their adjacent glutamatergic neurons. After chronic restraint stress, male mice displayed reliable nociception (control, mean ± SD: 0.34 ± 0.11 g, n = 7 mice; chronic restraint stress, 0.18 ± 0.11 g, n = 9 mice, P = 0.011). Comparable nociception phenotypes were observed in female mice. After chronic restraint stress, increased circuit activity was generated by disinhibition of glutamatergic neurons of the ventrolateral periaqueductal gray by local GABAergic interneurons via receiving enhanced central amygdala GABAergic inputs. Inhibition of this circuit increased nociception in chronic restraint stress mice (median [25th, 75th percentiles]: 0.16 [0.16, 0.16] g to 0.07 [0.04, 0.16] g, n = 7 mice per group, P < 0.001). In contrast, activation of this pathway reduced nociception (mean ± SD: 0.16 ± 0.08 g to 0.34 ± 0.13 g, n = 7 mice per group, P < 0.001).

CONCLUSIONS

These findings indicate that the central amygdala-ventrolateral periaqueductal gray pathway may mediate some aspects of pain symptoms under depression conditions.

The efficacy of ketamine in total knee arthroplasty: a randomized controlled trial protocol

BACKGROUND

Appropriate pain management is essential to improve the postoperative recovery after total knee arthroplasty (TKA). There is a paucity of literature on ketamine for TKA procedures. The aim of this study was to evaluate the analgesic efficacy of ketamine in patients undergoing primary TKA.

METHODS

This study was designed as a prospective, double blind, single center, randomized controlled trial. The participants were randomly assigned to either the ketamine or placebo groups, using a set of random numbers for the allocation sequence. All patients underwent TKA without patella resurfacing under spinal anesthesia. Preoperative workup, surgical technique, and postoperative management were standardized for all the patients. The primary outcome of this noninferiority study is opioid consumption within the first 24 hours following surgery, pain scores, distance ambulated, patient satisfaction, length of hospital stay, and complications.

RESULTS

The results of this study were expected to provide useful information on the effectiveness and safety of ketamine for immediate postoperative analgesia after TKA surgery.

TRIAL REGISTRATION

This study protocol was registered in Research Registry (researchregistry5575).

Ketamine induces rapid and sustained antidepressant-like effects in chronic pain induced depression: Role of MAPK signaling pathway

Chronic pain produces psychologic distress, which often leads to mood disorders such as depression. Co-existing chronic pain and depression pose a serious socio-economic burden and result in disability affecting millions of individuals, which urges the development of treatment strategies targeting this comorbidity. Ketamine, a noncompetitive antagonist of the N-methyl-d-aspartate (NMDA) receptor, is shown to be efficient in treating both pain and depression-related symptoms. However, the molecular characteristics of its role in chronic pain-induced depression remain largely unexplored. Hence, we studied the behavioral and molecular effects of a single systemic administration of ketamine (15 mg/kg, i.p.) on mechanical hypersensitivity and depressive-like consequences of chronic neuropathic pain. We showed that ketamine transiently alleviated mechanical hypersensitivity (lasting <24 h), while its antidepressant effect was observed even 72 h after administration. In addition, ketamine normalized the upregulated expression of the mitogen activated protein kinase (MAPK) phosphatase 1 (MKP-1) and the downregulated phosphorylation of extracellular signal-regulated kinase (pERK) in the anterior cingulate cortex (ACC) of mice displaying neuropathic pain-induced depressive-like behaviors. This effect of ketamine on the MKP-1 was first detected 30 min after the ketamine administration and persisted until up to 72 h. Altogether, these findings provide insight into the behavioral and molecular changes associated with single ketamine administration in the comorbidity of chronic pain and depression.

The efficacy of ketamine for postoperative pain control in adolescent patients undergoing spinal fusion surgery for idiopathic scoliosis

The use of ketamine in conjunction with morphine to reduce postoperative pain has been explored in several different surgery subtypes with conflicting results. Ketamine has shown promise to have both opioid sparing and analgesic effects in the postoperative setting. This study aimed to elucidate ketamine's ability to reduce morphine equivalent consumption and improve patient satisfaction after spinal fusion surgery for the correction of idiopathic scoliosis. This surgery is known to be associated with significant postoperative pain which impedes the ability to improve patient satisfaction, and may complicate the recovery timeline. Currently, the standard therapeutic regimen consists of patient-controlled analgesia morphine and the use of other opioids such as hydromorphone. A prospective, randomized double-blinded, placebo-controlled trial was performed to compare the standard morphine equivalent therapy alone against a standard therapy in conjunction with ketamine. Fifty adolescent patients were enrolled and randomized. Results yielded a significant reduction in postoperative morphine equivalent consumption (p = 0.042), adjusted postoperative pain scores (p < 0.001), and incidence of nausea and vomiting (p = 0.045). The application of ketamine as an analgesic in conjunction with the current standard of morphine equivalent therapy may serve as a superior pain control regimen for spinal surgeries in young population. This regimen enhancement may be generalizable to other surgery subtypes within similar populations. LEVEL OF EVIDENCE: Level I.

A rapid positive influence of S-ketamine on the anxiety of patients in palliative care: a retrospective pilot study

BACKGROUND

Patients in palliative care need rapid-acting pharmacological options for psychological distress. N-methyl-D-aspartate antagonist ketamine is known to have a fast onset of anti-depressant and anxiolytic action. Its S-enantiomer S-ketamine (or esketamine) is an analgesic used as a routine treatment for refractory pain as an intravenous infusion (0.25 mg/kg over 45 min). This study investigates whether S-ketamine pain therapy has a positive impact on psychological distress caused by anxiety and depression in palliative care.

METHODS

Patient routine data from a palliative care unit of a tertiary care hospital were used in a retrospective analysis after positive ethics approval. Eight patients, who received analgesic S-ketamine treatment, were compared to a control group matched by gender and age. The main analysis was conducted using three-way mixed MANOVA followed by two-way mixed ANOVA. Target variables were the values for anxiety and depression in the state-trait anxiety-depression inventory STADI. The predictor variables were the time of measurement before (T1) and after (T2) S-ketamine application and group membership.

RESULTS

Comparison of the S-ketamine group (n = 8; 4 male, 4 female; average age 52 years) with the control group (n = 8; 3 male, 5 female; average age 55 years) revealed a significant multivariate effect on anxiety and depression F(1, 14) = 4.78; p = 0.046; r = 0.50. The univariate comparisons showed a significant reduction of the anxiety scores from T1 to T2 in the S-ketamine group compared to the control group F(1, 14) = 10.14; p = 0.007; r = 0.65. With regard to depression, there was no significant reduction from T1 to T2 in the group comparison F(1, 14) = 1.60; p = 0.23; r = 0.32. No long-lasting effects on pain were found.

CONCLUSIONS

Our findings show that psychological distress of patients in palliative care may improve after a single administration of S-ketamine, which mainly alleviates anxiety in those patients. Limitations of this study arise from non-randomization, retrospective analysis and low sample size. Therefore, further prospective and ideally randomized studies are necessary.

Indian Society for Study of Pain, Cancer Pain Special Interest Group Guidelines on Pharmacological Management of Cancer Pain (Part III)

The Indian Society for Study of Pain (ISSP), Cancer Pain Special Interest Group, guidelines on pharmacological management of cancer pain in adults provide a structured, step-wise approach which will help to improve the management of cancer pain and to provide patients with a minimally acceptable quality of life. The guidelines have been developed based on the available literature and evidence, to suit the needs, patient population, and situations in India. A questionnaire based on the key elements of each sub draft addressing certain inconclusive areas where evidence was lacking, was made available on the ISSP website and circulated by E-mail to all the ISSP and Indian Association of Palliative Care members. Antidepressants and/or anticonvulsants should be used to treat neuropathic cancer pain and the dose should be titrated according to the clinical response and side effects. External beam radiotherapy should be offered to all patients with painful metastatic bone pain. There is evidence on the use of ketamine in cancer neuropathic pain, but with no beneficial effect, thus it is not recommended.

The Pharmacology of Visual Hallucinations in Synucleinopathies

Visual hallucinations (VH) are commonly found in the course of synucleinopathies like Parkinson's disease and dementia with Lewy bodies. The incidence of VH in these conditions is so high that the absence of VH in the course of the disease should raise questions about the diagnosis. VH may take the form of early and simple phenomena or appear with late and complex presentations that include hallucinatory production and delusions. VH are an unmet treatment need. The review analyzes the past and recent hypotheses that are related to the underlying mechanisms of VH and then discusses their pharmacological modulation. Recent models for VH have been centered on the role played by the decoupling of the default mode network (DMN) when is released from the control of the fronto-parietal and salience networks. According to the proposed model, the process results in the perception of priors that are stored in the unconscious memory and the uncontrolled emergence of intrinsic narrative produced by the DMN. This DMN activity is triggered by the altered functioning of the thalamus and involves the dysregulated activity of the brain neurotransmitters. Historically, dopamine has been indicated as a major driver for the production of VH in synucleinopathies. In that context, nigrostriatal dysfunctions have been associated with the VH onset. The efficacy of antipsychotic compounds in VH treatment has further supported the notion of major involvement of dopamine in the production of the hallucinatory phenomena. However, more recent studies and growing evidence are also pointing toward an important role played by serotonergic and cholinergic dysfunctions. In that respect, in vivo and post-mortem studies have now proved that serotonergic impairment is often an early event in synucleinopathies. The prominent cholinergic impairment in DLB is also well established. Finally, glutamatergic and gamma aminobutyric acid (GABA)ergic modulations and changes in the overall balance between excitatory and inhibitory signaling are also contributing factors. The review provides an extensive overview of the pharmacology of VH and offers an up to date analysis of treatment options.

Ketamine sensitization: Influence of dose, environment, social isolation and treatment interval

Ketamine is a dissociative anesthetic first developed in the 1960s but is increasingly used at subanesthetic doses for both clinical and non-clinical purposes. There is evidence from human recreational users of compulsive use and addiction. Sensitization is an increase in an effect of a drug with repeated use that is thought to be important in the development of addiction. Research on psychomotor stimulants has shown the development of sensitization in laboratory animals to be modified by factors that influence addiction. In the current paper we describe four experiments on the development of sensitization in laboratory rats aimed at determining if ketamine sensitization is also influenced by factors thought to be important in addiction. Adult, male Sprague-Dawley rats received ketamine (5, 10, 20 or 50 mg/kg i.p.) for five or more days and the development of locomotor sensitization was followed. Experiment 1 examined the ability of low doses of ketamine to produce sensitization and found sensitization at 5, 10 and 20 mg/kg. Experiment 2 examined the influence of environmental context and found that ketamine sensitization (20 mg/kg) was greater when administration occurred in a novel environment (the experimental apparatus) than in home cages. Experiment 3 found that ketamine sensitization (20 mg/kg) did not occur when animals were housed in social isolation but occurred readily in pair-housed animals. Finally, Experiment 4 found that ketamine sensitization (20 or 50 mg/kg) was similar whether drug was administered daily or at 3-day intervals. Together, the results demonstrate that ketamine sensitization is robust and reliable, occurring under a variety of circumstances. Moreover, ketamine sensitization is influenced by factors that influence the development of addiction in humans. The current results may lead to a better understanding of ketamine abuse and addiction and may help inform clinical use of the drug.

Subanesthetic ketamine infusions for the management of pediatric pain in non-critical care settings: An observational analysis

BACKGROUND

Guidelines issued by the American Society of Regional Anesthesia and Pain Medicine suggest that ketamine infusions for acute pain management are advantageous as a primary treatment or as an opioid adjunct. Despite significant data regarding its use in adult patients, there remains a paucity of information related to its quality and side effect profile in pediatrics and how it can be effectively used. We aimed to summarize our practice of utilizing ketamine for pediatric pain management in non-critical care settings.

METHODS

Patients aged 0-21 years receiving low-dose ketamine infusions (≤0.3 mg/kg/hour) in inpatient care units over five years were retrospectively analyzed. Demographics, specific quality metrics, and side effects were quantified.

RESULTS

About 172 patients received 270 subhypnotic ketamine infusions. The median duration of the infusions was 63.8 hours and 0.2 mg/kg/hour for the highest dose. The primary indication for ketamine was chronic pain exacerbation (83.3%). Despite similar opioid consumption, there was a significant reduction in mean verbal pain scores before (8.9 ± 1.9, P < .001) and after ketamine (6.5 ± 2.7, P < .001) use. Although there were 52 incidences of some side effect (neurologic excitability [10.4%]; over-sedation [7.4%]; rapid response team alerts [1.1%]), none resulted in termination of the infusion or escalations in care.

CONCLUSION

Ketamine can effectively be used as part of a multimodal analgesic regimen in pediatric patients in non-critical care settings. Our five-year experience using low-dose ketamine infusions highlights an acceptable side effect profile, with no attributable escalations in care or serious adverse events.

Effect of morphine and a low dose of ketamine on the T cells of patients with refractory cancer pain in vitro

The combination of morphine and ketamine is considered safe and efficacious in many patients. However, a considerable number of immunomodulatory effects have been reported to be produced by both morphine and ketamine. The aim of the present study was to assess the direct effect of morphine and a low dose of ketamine on the T cells of patients with refractory cancer pain in vitro. Venous blood was obtained from patients with refractory cancer pain and peripheral blood mononuclear cells were isolated using the Ficoll-Hypaque density gradient method. Anti-CD3 beads were used to isolate T cells by positive selection. Subsequently, the T cells were treated with vehicle, 200 ng/ml of morphine or 200 ng/ml of morphine + 100 ng/ml ketamine for 24 h, following which the cells were stimulated with anti-CD3 and anti-CD28. Flow cytometric analysis of CD3⁺ T cells, and interleukin (IL)-2 and interferon (IFN)-γ in the supernatant, reverse transcription-quantitative PCR analysis for the detection of IL-2 and IFN-γ and western blotting for the detection of p65 nuclear factor (NF)-κB were performed. In vitro, the CD4⁺ and CD8⁺ T cell counts, CD4⁺/CD8⁺ ratio, secretion of IL-2 and IFN-γ in the supernatant, mRNA expression levels of IL-2 and IFN-γ and expression of p65 NF-κB were significantly decreased following treatment with morphine and morphine + ketamine, compared with results in the control group (all P<0.05). However, there was no significant difference between treatment with morphine and that with morphine + ketamine. Treatment with morphine + ketamine in vitro decreased the immune functions of patients with refractory cancer pain, although the effect of treatment with morphine and a low dose of ketamine did not differ significantly from that with morphine treatment alone.

Ketamine applications beyond anesthesia - A literature review

Ketamine's clinical use began in the 1970s. Physicians benefited from its safety and ability to induce short-term anesthesia and analgesia. The psychodysleptic effects caused by the drug called its further clinical use into question. Despite these unpleasant effects, ketamine is still applied in veterinary medicine, field medicine, and specialist anesthesia. Recent intensive research brought into light new possible applications of this drug. It began to be used in acute, chronic and cancer pain management. Most interesting reports come from research on the antidepressive and antisuicidal properties of ketamine giving hope for the creation of an effective treatment for major depressive disorder. Other reports highlight the possible use of ketamine in treating addiction, asthma and preventing cancer growth. Besides clinical use, the drug is also applied to in animal model of schizophrenia. It seems that nowadays, with numerous possible applications, the use of ketamine has returned; to its former glory. Nevertheless, the drug must be used with caution because still the mechanisms by which it executes its functions and long-term effects of its use are not fully known. This review aims to discuss the well-known and new promising applications of ketamine.

Prehospital Use of Ketamine: Effectiveness in Critically Ill and Injured Patients

BACKGROUND

The military use of ketamine is well established. The benefits of prehospital civilian use have not been extensively reported.

METHODS

A retrospective review was performed of patients with prehospital ketamine use in Mayo One's air and critical care ground transport.

RESULTS

The medical records were reviewed from 2014 to 2016 to assess the efficacy of Ketamine. During this time frame, 158 (167 instances) patients were treated with ketamine for analgesia (38%), sedation (44%), or procedural (18%) use. The patient population had a mean age of 49 (range: 1-100), with 105 (67%) male patients. Indications included trauma (69%), which was further broken down into blunt (57%), penetrating (4%), and miscellaneous (8%), and medical illness (31%). The mean ketamine dose was 52.6 mg (range: 5-200 mg) via intravenous route. Ketamine was utilized in 61% of patients after other medications were ineffective. Overall success rate was 98%. Mean pain scale before and after ketamine use was 9/10 and 3/10, respectively. Ketamine use increased yearly from 21 (13%) in 2014, 56 (36%) in 2015, and 81 (51%) in 2016.

CONCLUSION

Prehospital ketamine use is effective alone or in conjunction with other medications for analgesia, sedation, and procedural use in trauma and critically ill patients with minimal hemodynamic and respiratory consequences.

N-Methyl-d-aspartate receptor open-channel blockers memantine and magnesium modulate nociceptive trigeminovascular neurotransmission in rats

Experimental and clinical studies suggest that the low-affinity N-methyl-d-aspartate (NMDA) receptor open-channel blockers Mg²⁺ and memantine are effective in reducing trigeminal nociceptive activation. The aim of this study was to investigate the apparent effectiveness of these channel blockers using a model of trigeminal activation in vivo. Rats were anaesthetized before electrically stimulating the dura mater adjacent the middle meningeal artery. Neurons responding to stimulation were recorded extracellularly using electrophysiological methods. l-Glutamate or NMDA, and Mg²⁺ , memantine, or sodium controls were applied locally using microiontophoresis. Microiontophoretic application of Mg²⁺ or memantine into the trigeminocervical complex inhibited mechanically and electrically stimulated craniovascular afferents,  and l-glutamate or NMDA-evoked neuronal activity at the second-order trigeminal synapse of craniovascular afferents. By contrast, intravenous administration of MgSO₄ (100 mg/kg) or memantine (10 mg/kg) did not significantly affect electrically stimulated afferent-evoked activity within the trigeminocervical complex. The Mg²⁺ and memantine concentrations achieved after systemic administration may not effectively inhibit activation of the trigeminocervical complex, perhaps providing an explanation for the relatively poor efficacy of these NMDA receptor open-channel blockers for headache treatment in clinical studies. Nevertheless, the present results suggest blocking of NMDA-receptor open channels inhibits nociceptive activation of the trigeminocervical complex. Further exploration of such channel blockers as a therapeutic strategy for primary head pain is warranted.

Low-dose ketamine adjuvant treatment for refractory pain in children, adolescents and young adults with cancer: a pilot study

OBJECTIVES

Ketamine, an N-methyl-D-aspartate receptor antagonist, is effective at relieving adult cancer pain, although there have been very few reports to date regarding its use in children and in adolescents and young adults (AYA). This study assessed the efficacy, safety and opioid-sparing effects of low doses of ketamine added to opioid analgesics to alleviate persistent cancer pain.

METHODS

This prospective, multicentre, observational trial collected data regarding demographics, pain characteristics, pain score assessment within the first 48 hours of ketamine administration, tolerance and satisfaction from 38 patients aged 2-24 years prescribed with ketamine as an adjuvant antalgic for refractory cancer pain in 10 French paediatric oncology centres.

RESULTS

The mean visual analogue scale pain score decreased from 6.7 to 4.3 out of 10 (n=39, p<0.001) from day 1 to day 3 and by at least 2 points in 56% of the patients (n=22) 48 hours after initiation of ketamine. Nine patients experienced poor tolerance (≥2 side effects), all with infusion rates lower than 0.05 mg/kg/hour. None had limiting toxicities. An opioid-sparing effect was highlighted in four patients. Fifty-four per cent of the prescribers and 47% of the patients found the addition of ketamine 'very helpful'.

CONCLUSIONS

Low doses of ketamine as an adjuvant to opioids significantly reduced the intensity of pain in half of the study population. A tendency towards better pain control is shown, although a lack of statistical power somewhat limits our conclusions, especially in children. Nevertheless, ketamine may be a useful option for improving the treatment of refractory pain in children and AYA with cancer.

A survey for ketamine abuse and its relation to the lower urinary tract symptoms in Taiwan

We aimed to explore the correlation between ketamine abuse and lower urinary tract symptoms (LUTS) and epidemiology of ketamine cystitis. Questionnaire records of ketamine abusers, such as sex, age, and details of using ketamine, including consumption method, amount, duration of ketamine use, and LUTS, were obtained from two private rehabilitation centers. We analyzed these factors and established a severity forecasting module. One hundred and six ketamine abusers completed the questionnaires. LUTS showed an onset time of 24.67 ± 26.36 months among ketamine abusers. Overactive bladder symptom score, international prostate symptom score-storage, interstitial cystitis symptom index, interstitial cystitis problem index, and visual analogue scale score were 5.25 ± 4.43, 5.95 ± 5.72, 10.96 ± 6.66, 9.73 ± 5.82, and 2.55 ± 3.18, respectively. All symptom scores were positively correlated with the duration of ketamine abuse. Ketamine snorting was significantly correlated with all symptom scores compared to smoking. Hydrodistention, intravesical hyaluronic acid instillation, intravesical injection with botulinum toxin, and hyperbaric-oxygen therapy showed better effect than oral treatment. Ketamine can induce severe storage symptoms, such as frequency or nocturia depending on the duration of abuse. Ketamine snorting may cause worse LUTS than smoking. Combining ketamine and other substances may exacerbate LUTS. Intravesical therapy may lead to better outcomes than oral treatment.

Cellular Signaling in Müller Glia: Progenitor Cells for Regenerative and Neuroprotective Responses in Pharmacological Models of Retinal Degeneration

Retinal degenerative diseases are a leading cause of visual impairment or blindness. There are many therapies for delaying the progression of vision loss but no curative strategies currently. Stimulating intrinsic neuronal regeneration is a potential approach to therapy in retinal degenerative diseases. In contrast to stem cells, as embryonic/pluripotent stem cell-derived retinal progenitor cell or mesenchymal stem cells, Müller glia provided an endogenous cellular source for regenerative therapy in the retina. Müller glia are a major component of the retina and considerable evidence suggested these cells can be induced to produce the lost neurons in several species. Understanding the specific characteristic of Müller glia to generate lost neurons will inspire an attractive and alternative therapeutic strategy for treating visual impairment with regenerative research. This review briefly provides the different signal transduction mechanisms which are underlying Müller cell-mediated neuroprotection and neuron regeneration and discusses recent advances about regeneration from Müller glia-derived progenitors.

CE: Original Research: The Efficacy and Safety of an RN-Driven Ketamine Protocol for Adjunctive Analgesia During Burn Wound Care

: Objective: Traditional analgesic regimens often fail to control the severe pain patients experience during burn wound care, and the drugs are frequently administered at doses that can cause oversedation and respiratory depression. Ketamine may be an ideal agent for adjunctive analgesia in such patients because of its unique mechanism of action and lack of association with respiratory depression. This study evaluated the efficacy and safety of a critical care RN-driven protocol for IV ketamine administration during burn wound care.

METHODS

This retrospective cohort study examined all adult burn patients who received ketamine as part of a critical care RN-driven ketamine protocol for burn wound care from September 2011 through September 2013. Efficacy outcomes were opioid and benzodiazepine requirements (expressed as fentanyl and midazolam equivalents, respectively) four hours after ketamine administration compared with four hours before such administration. Safety parameters assessed were neurologic, hemodynamic, and respiratory effects.

RESULTS

Twenty-seven patients received 56 ketamine doses as part of this protocol; the mean (SD) dose was 0.75 (0.35) mg/kg. Twenty patients (74%) were male and seven (26%) were female; mean age was 39 years. The average percentage of total body surface area burned was 23.4%. With the protocol, opioid and benzodiazepine requirements were reduced by 29% and 20%, respectively. One patient experienced an episode of oversedation after concomitant administration of ketamine and fentanyl. No patients experienced neurologic or hemodynamic complications following ketamine administration.

CONCLUSIONS

The administration of ketamine during burn wound care using a critical care RN-driven protocol was associated with reduced opioid and benzodiazepine requirements and few adverse effects. Prospective studies are needed to investigate additional patient outcomes and the independent administration of ketamine by critical care RNs.

Novel Approaches for Treating Pain in Children

PURPOSE OF REVIEW

Good pain management in children, especially those at end of life, is a crucial component of palliative medicine. The current review assesses some of the new and/or innovative ways to manage pain in children. The article focuses on some recent medications/pharmaceutical options such as cannabinoids and also innovative ways to administer medication to children, such as intranasal and inhalation.

RECENT FINDINGS

Current approaches to pain management now include (1) new uses of old drugs such as ketamine and lidocaine, (2) use of new drugs/medications such as cannabinoids, and (3) creative use of old technology such as atomizers, intranasal drops, and inhalation. Typically, novel approaches to care rarely start in pediatrics or palliative care. The current review has presented some new and old drugs being utilized in new and old ways.

Quality control and stability of ketamine, remifentanil, and sufentanil syringes in a pediatric operating theater

BACKGROUND

Transforming a drug from its commercial form into a ready-to-use drug is common practice, especially in pediatrics. However, the risk of compounding error is real and data on drug stability in practice are not always available.

AIMS

The aim of this study was to assess, in real conditions, both the error rate and stability of three drugs: ketamine, remifentanil, and sufentanil.

METHODS

A new rapid and easy-to-use high-performance liquid chromatography method with a diode array detector has been developed and validated to quantify these drugs and detect their degradation products. Over a 1-month period, 151 syringes were collected in the postanesthesia care unit. Seventy-three were stock solution syringes containing a 10-fold dilution of commercial drugs and 78 were serial dilution syringes made from successive dilutions of stock solutions. A comparison between real and expected concentrations as well as the detection of possible degradation products was carried out on these samples.

RESULTS

All stock solution syringes had good chemical stability throughout the working day. A 4-µg/mL remifentanil serial dilution syringe, however, had to be discarded as a degradation peak was detected. Overall, 15.3% (95% CI, 9.5-21.1%) of syringes had a drug concentration outside the ±10% acceptability range, that is, 11.0% (95% CI, 3.7-18.2%) and 19.5% (95% CI, 10.6%-28.4%) of stock and diluted syringes respectively, with drug amounts ranging from -25.3% to 22.0%. The highest error rates were observed with sufentanil syringes: 20% and 28% for stock solution and serial dilution, respectively.

CONCLUSION

The study shows that stock solution syringes prepared in advance are chemically stable throughout the day, unlike certain serial dilution syringes, indicating that the latter should be prepared just before administration to ensure chemical stability. Our results show that the error rate for serial dilution syringes is twice that of stock solution. Different safety measures are under discussion and have to be further studied.

Topical treatments for diabetic neuropathic pain

Diabetic neuropathic pain (DNP) has a huge impact on quality of life and can be difficult to treat. Oral treatment is the most frequently used method for DNP, but its use is often limited by systemic side effects. Topical use of drugs as an alternative option for DNP treatment is currently gaining interest. In the present review, a summary is provided of the available agents for topical use in patients with DNP, including lidocaine plasters or patches, capsaicin cream, gel or patches, amitriptyline cream, clonidine gel, ketamine cream, extracts from medicinal plants including nutmeg extracts and Citrullus colocynthis extract oil, and certain compounded topical analgesics. Furthermore, the potential efficacy of these treatments is addressed according to the available clinical research literature. It has been indicated that these topical drugs have the potential to be valuable additional options for the management of DNP, with adequate safety and continuous long-term treatment efficacy. Compounded topical agents are also effective and safe for patients with DNP and could be another area worthy of further investigation based on the strategy of using low-dose, complementary therapies for DNP. The findings indicate that developing topical drugs acting on different targets in the process of DNP is a valuable area of future research.

Nonanesthetic Effects of Ketamine: A Review Article

Ketamine is considered a dissociative anesthetic medication, and it is commonly administered by a parenteral route. It works mainly by blocking the N-methyl-D-aspartate receptor. It inhibits the voltage-gated Na and K channels and serotonin and dopamine reuptake; also, it affects specific receptors, such as α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, kainate, and aminobutyric acid A receptors. Ketamine appears to have particular mechanisms that are potentially involved during analgesic induction, including enhancing of descending inhibition and antiinflammatory effects. More recently, it has been shown that ketamine has potential in clinical practice for the management of chronic pain, cognitive function, depression, acute brain injury, and disorders of the immune system.

Systematic review of pharmacological therapies for the management of ischaemic pain in patients with non-reconstructable critical limb ischaemia

BACKGROUND

Critical limb ischaemia (CLI) is a severe manifestation of peripheral arterial disease, characterised by chronic ischaemic rest pain, ulcers or gangrene. Management of ischaemic pain is challenging in patients with no options for revascularisation and optimal pharmacological therapies have not been established.

OBJECTIVES

To identify and evaluate the effectiveness of pharmacological therapies to treat ischaemic pain secondary to non-reconstructable CLI.

METHODS

This systematic review was reported in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guideline. Comprehensive searches of three electronic databases, a PubMed-related articles link search, grey literature search and hand-searches of the bibliographies of relevant papers and textbooks were performed. Studies recruiting adult patients with CLI of any aetiology were eligible for inclusion. Surgical and revascularisation procedures, and all invasive interventions were excluded.

RESULTS

Of 792 studies, six met full inclusion criteria. These studies researched the use of intravenous lidocaine, intravenous ketamine, oral gabapentin and the combination of transdermal buprenorphine and epidural morphine/ropivacaine infusion. All studies showed an improvement in severity of ischaemic pain in CLI but with varying side effect profiles and quality. The extracted studies showed substantial heterogeneity and therefore a meta-analysis was not performed.

CONCLUSION

The pharmacological management of pain secondary to non-reconstructable CLI is a challenging review topic. No recommendations of pharmacological agents can be made following this review but a number of novel approaches to manage pain in this cohort have shown positive results and require further investigation.

Ketamine for pain management

Supplemental Digital Content is Available in the Text.

Emerging Trends in Pain Medication Management: Back to the Future: A Focus on Ketamine

Providers face many challenges when faced with pain management. Pain is complex, difficult to understand and diagnose, and especially enigmatic to manage. The discovery of nonopioid agents for pain management has become particularly important considering the ongoing opioid epidemic. This review is focused on revisiting ketamine, an agent that has historically been used for anesthesia, in new ways to manage pain. Ketamine has unique pharmacologic properties that may prevent the development of pain as well as reduce chronic pain. This has led to the use of ketamine for perioperative analgesia as well as chronic pain syndromes. In select patients with pain refractory to other treatment modalities, ketamine may provide much needed relief.

Pain Management in the Emergency Department: a Review Article on Options and Methods

CONTEXT

The aim of this review is to recognizing different methods of analgesia for emergency medicine physicians (EMPs) allows them to have various pain relief methods to reduce pain and to be able to use it according to the patient's condition and to improve the quality of their services.

EVIDENCE ACQUISITION

In this review article, the search engines and scientific databases of Google Scholar, Science Direct, PubMed, Medline, Scopus, and Cochrane for emergency pain management methods were reviewed. Among the findings, high quality articles were eventually selected from 2000 to 2018, and after reviewing them, we have conducted a comprehensive comparison of the usual methods of pain control in the emergency department (ED).

RESULTS

For better understanding, the results are reported in to separate subheadings including "Parenteral agents" and "Regional blocks". Non-opioids analgesics such as nonsteroidal anti-inflammatory drugs (NSAIDs) and acetaminophen are commonly used in the treatment of acute pain. However, the relief of acute moderate to severe pain usually requires opioid agents. Considering the side effects of systemic drugs and the restrictions on the use of analgesics, especially opioids, regional blocks of pain as part of a multimodal analgesic strategy can be helpful.

CONCLUSION

This study was designed to investigate and identify the disadvantages and advantages of using each drug to be able to make the right choices in different clinical situations for patients while paying attention to the limitations of the use of these analgesic drugs.

Illicit drug ketamine induces adverse effects from behavioral alterations and oxidative stress to p53-regulated apoptosis in medaka fish under environmentally relevant exposures

With increasing problems of drug abuse worldwide, aquatic ecosystems are contaminated by human pharmaceuticals from the discharge of hospital or municipal effluent. However, ecotoxicity data and related toxic mechanism for neuroactive controlled or illicit drugs are still lacking, so assessing the associated hazardous risk is difficult. This study aims to investigate the behavioral changes, oxidative stress, gene expression and neurotoxic or apoptosis effect(s) in larvae of medaka fish (Oryzias latipes) with environmentally relevant exposures of ketamine (KET) solutions for 1-14 days. KET exposure at an environmentally relevant concentration (0.004 μM) to 40 μM conferred specific patterns in larval swimming behavior during 24 h. At 14 days, such exposure induced dose- and/or time-dependent alteration on reactive oxygen species induction, the activity of antioxidants catalase and superoxide dismutase, glutathione S-transferase and malondialdehyde contents in fish bodies. KET-induced oxidative stress disrupted the expression of acetylcholinesterase and p53-regulated apoptosis pathways and increased caspase expression in medaka larvae. The toxic responses of medaka larvae, in terms of chemical effects, were qualitatively analogous to those of zebrafish and mammals. Our results implicate a toxicological impact of waterborne KET on fish development and human health, for potential ecological risks of directly releasing neuroactive drugs-containing wastewater into the aquatic environment.

Case Report: Utility of Ketamine, Lidocaine, and Mexiletine as Nonopioid Adjuvants in Complex Cancer-Associated Pain

Ketamine, lidocaine, and mexiletine are potential nonopioid adjuvant medications for the use of refractory cancer-related pain, particularly when opioids are demonstrating limited objective benefit. This is a case report of a single patient admitted to a large academic medical center in the United States. The patient is a 43-year-old woman with a history of Crohn's disease complicated by rectal squamous cell carcinoma and complex, progressive, and intractable pelvic and rectal pain. Over the course of hospitalization, her pain demonstrated limited opioid responsiveness despite marked fluctuations of her oral morphine equivalent doses. She also demonstrates variable responsiveness to ketamine. Lidocaine continuous infusion ultimately proves beneficial, and she is discharged after conversion to oral mexiletine. An overview of the hospital system's protocols for ketamine and lidocaine continuous infusions for pain and considerations for transitioning to mexiletine from lidocaine infusion are included.

Ketamine for the treatment of major depressive disorder and bipolar depression: A review of the literature

Introduction

Over the past decade, ketamine has been studied for major depressive disorder and bipolar depression. Ketamine is believed to exert its antidepressant properties through N-methyl-D-aspartate receptor antagonism.

Methods

Study authors completed a literature review of seven randomized controlled trials of ketamine usage in major depressive disorder and bipolar depression.

Results

Ketamine demonstrated a statistically significant improvement over placebo or midazolam in major depressive disorder. Ketamine also exhibited a statistically significant improvement over placebo in bipolar depression.

Discussion

Ketamine has shown promise in quickly reducing symptoms in patients with treatment resistant depression and bipolar depression. Using ketamine may be helpful for patients that have exhausted other therapeutic options.

Factors Affecting Long-Term Postoperative Narcotic Use in Discectomy Patients

BACKGROUND

Long-term narcotic use has risks and potentially life-threatening opioid-related side effects. Extended narcotic use in patients undergoing discectomy raises concerns of other underlying causes of pain or overprescription and/or abuse. The goal of this study was to determine which factors have an effect on active narcotic prescription >3 months after discectomy.

METHODS

The PearlDiver Database was used in this study. Patients 30-55 years old undergoing discectomy without fusions were queried for active narcotic drug prescription occurring >30 days and >3 months after original surgery. Medical co-diagnoses were independently analyzed for effects on long-term active narcotic prescriptions. Prior narcotic use was defined by use within 4 months before surgery.

RESULTS

Of 1321 patients undergoing discectomy, 621 had actively prescribed narcotics >3 months after surgery. Preoperative narcotic use had the largest effect on odds of postoperative prescription (odds ratio [OR] = 3.4). Medical comorbidities increasing odds of long-term narcotic prescriptions included migraines (OR = 1.4), diabetes mellitus (OR = 1.4), depression (OR = 1.6), and smoking (OR = 1.9).

CONCLUSIONS

Narcotic abuse is a serious problem rooted in overprescription of these drugs, which has ultimately led to much more caution in prescribing among physicians. Because pain management and drug prescription must be balanced, identifying patients who may be susceptible to narcotic overprescription is important. Patients with co-diagnoses increasing odds of long-term narcotic prescriptions would benefit from early and continual postsurgical follow-up to ensure accurate pain management and to determine if narcotic prescriptions are justly warranted in the later postoperative period.

Intra-articular injections of ketamine and 25% dextrose improve clinical and pathological outcomes in the monosodium iodoacetate model of osteoarthritis

BACKGROUND

The study evaluated the effect of intra-articular injections of ketamine and 25% dextrose with triamcinolone acetate (TA) and hyaluronic acid (HA) on joint pathology and pain behavior in monosodium iodoacetate (MIA)-induced osteoarthritis (OA) in experimental mice.

METHODS

In phase I, the MIA-induced OA model was standardized. In phase II, mice were divided into three groups: disease controls (DC), ketamine 12 mg/kg (K12) and ketamine 24 mg/kg (K24) to select an effective dose of ketamine for phase III. In phase III, the groups were: DC, normal controls (NC), K24, 25% dextrose (D25) - 10 μL, TA 6 mg/kg, and HA - 3.5 mg/kg. The effect of ketamine was compared with the standard drugs - TA and HA. In phases II and III, after 7 days following the induction of OA, animals were subjected to weekly behavioral tests and biweekly drug administration from week 2 to week 4. Subsequently, after 4 weeks knee joint samples were collected and sent for histopathological evaluation to a veterinary pathologist.

RESULTS

In phase I, the DC group showed significant OA changes as compared to NC on knee joint histopathology scoring. In phase II, all the behavioral tests and knee joint histopathology results demonstrated a significant improvement with K24 as compared to DC. In phase III, significant differences were found between DC vs. HA, DC vs. D25, DC vs. K24, K24 vs. TA, HA vs. TA for open field test and hot plate test (p<0.001), whereas HA and ketamine showed comparable results for these tests. There was a significant improvement in D25, TA and K24, HA groups as compared to DC in histopathology scores, (p<0.05).

CONCLUSIONS

The NMDA antagonist effect of ketamine and the proliferative effect of 25% dextrose showed a reduction in pain and disease activity in the OA model.