Use of oral ketamine in chronic pain management: a review

Pain and Perception: Exploring Psychedelics as Novel Therapeutic Agents in Chronic Pain Management

PURPOSE OF REVIEW

Chronic pain affects approximately 1.5 billion people worldwide, representing the leading cause of disability and a significant financial burden on healthcare systems. Conventional treatments, such as opioids and non-steroidal anti-inflammatory drugs, are frequently linked to adverse effects, including dependency and gastrointestinal issues, and often offer limited long-term relief. This review explores the potential of psychedelics, including psilocybin, LSD, and ketamine, as alternative therapeutic agents in chronic pain management.

RECENT FINDINGS

These substances modulate pain perception through actions on serotonergic and glutamatergic systems and may promote neuroplasticity, offering novel pathways for pain relief. Specifically, the review details the pharmacologic actions of psychedelics, their effects on chronic pain syndromes such as cancer pain, migraines, and neuropathic pain, and their clinical implications. The safety profiles, patient responses, and analgesic properties of these compounds are examined, highlighting the need for further research to validate their efficacy and optimize their therapeutic use in pain management.

Comparison of the effect of intraoperative dexmedetomidine versus ketamine on postoperative analgesia in fracture femur patients operated under subarachnoid block - A prospective randomized double-blind controlled trial

Background and Aims

Intravenous sedation during spinal anesthesia has the advantages of increased duration of spinal anesthesia and better postoperative pain control. The aim of this study was to compare the effect of intravenous bolus and infusion of dexmedetomidine versus ketamine given intraoperative on the postoperative analgesia in fracture femur patients operated under subarachnoid block.

Material and Methods

In this prospective randomized double-blind controlled study, 75 patients aged 18-65 years posted for elective surgery were selected and randomly divided into three groups to receive ketamine (group K), dexmedetomidine (group D), and saline (control group C). Postoperative pain was evaluated using the numerical rating scale (NRS). The duration of analgesia and the amount of analgesic consumption were also recorded. Student's t-test and Chi-square test were used to compare the two groups, and one-way ANOVA with posthoc analysis was performed for comparison of the three groups.

Results

Patients in the ketamine group had better postoperative analgesia as assessed by decreased pain (on the NRS scale) and decreased need for postoperative rescue analgesics (P < 0.001). The duration of sensory block and motor block was prolonged in group K as compared to the other two groups (P < 0.001).

Conclusion

Intraoperative use of intravenous ketamine was superior to dexmedetomidine for postoperative analgesia in fracture femur patients operated under subarachnoid block.

Ketamine-assisted buprenorphine initiation: a pilot case series

BACKGROUND

Many people with opioid use disorder who stand to benefit from buprenorphine treatment are unwilling to initiate it due to experience with or fear of both spontaneous and buprenorphine-precipitated opioid withdrawal (BPOW). An effective means of minimizing withdrawal symptoms would reduce patient apprehensiveness, lowering the barrier to buprenorphine initiation. Ketamine, approved by the FDA as a dissociative anesthetic, completely resolved BPOW in case reports when infused at a sub-anesthetic dose range in which dissociative symptoms are common. However, most patients attempt buprenorphine initiation in the outpatient setting where altered mental status is undesirable. We explored the potential of short-term use of ketamine, self-administered sublingually at a lower, sub-dissociative dose to assist ambulatory patients undergoing transition to buprenorphine from fentanyl and methadone.

METHODS

Patients prescribed ketamine were either (1) seeking transition to buprenorphine from illicit fentanyl and highly apprehensive of BPOW or (2) undergoing transition to buprenorphine from illicit fentanyl or methadone and experiencing BPOW. We prescribed 4-8 doses of sublingual ketamine 16 mg (each dose bioequivalent to 3-6% of an anesthetic dose), monitored patients daily or near-daily, and adjusted buprenorphine and ketamine dosing based on patient response and prescriber experience.

RESULTS

Over a period of 14 months, 37 patients were prescribed ketamine. Buprenorphine initiation was completed by 16 patients, representing 43% of the 37 patients prescribed ketamine, and 67% of the 24 who reported trying it. Of the last 12 patients who completed buprenorphine initiation, 11 (92%) achieved 30-day retention in treatment. Most of the patients who tried ketamine reported reduction or elimination of spontaneous opioid withdrawal symptoms. Some patients reported avoidance of severe BPOW when used prophylactically or as treatment of established BPOW. We developed a ketamine protocol that allowed four of the last patients to complete buprenorphine initiation over four days reporting only mild withdrawal symptoms. Two patients described cognitive changes from ketamine at a dose that exceeded the effective dose range for the other patients.

CONCLUSIONS

Ketamine at a sub-dissociative dose allowed completion of buprenorphine initiation in the outpatient setting in the majority of patients who reported trying it. Further research is warranted to confirm these results and develop reliable protocols for a range of treatment settings.

Increasing the bioavailability of oral esketamine by a single dose of cobicistat: A case study

Background

Intranasal esketamine is an approved drug for treatment‐resistant depression (TRD); however, it is costly and may result in specific adverse effects. In this single case study, we explored if oral esketamine can be a suitable alternative.

Methods

In collaboration with a 39‐year‐old female with TRD, we compared plasma concentration curves of intranasal (84 mg) and oral (1, 2 and 4 mg/kg) esketamine. Because oral esketamine has a relatively low bioavailability, it results in a different ratio between esketamine and its primary metabolite noresketamine. To increase the bioavailability of oral esketamine, we co‐administered a single dose of the cytochrome P‐450 (CYP) 3A4 inhibitor cobicistat (150 mg).

Results

For all doses administered, oral esketamine resulted in lower esketamine but higher noresketamine peak plasma concentrations compared with intranasal treatment. Using oral esketamine it was not possible to generate a similar esketamine plasma concentration curve as with the intranasal treatment, except when combined with cobicistat (esketamine 2 mg/kg plus cobicistat 150 mg).

Conclusions

Our findings demonstrate that cobicistat effectively increases the bioavailability of oral esketamine. Further research is required in a larger population, especially to investigate the clinical benefit of cobicistat as a booster drug for oral esketamine.

Oral ketamine may offer a solution to the ketamine conundrum

Ketamine has received considerable attention for its rapid and robust antidepressant response over the past decade. Current evidence, in clinical populations, predominantly relates to parenterally administered ketamine, which is reported to produce significant undesirable side effects, with additional concerns regarding long-term safety and abuse potential. Attempts to produce a similar drug to ketamine, without the psychotomimetic side effects, have proved elusive. Orally administered ketamine has a different pharmacological profile to parentally administered ketamine, suggesting it may be a viable alternative. Emerging evidence regarding the efficacy and tolerability of oral ketamine suggests that it may be a favourable route of administration, as it appears to obtain similarly beneficial treatment effects, but without the cost and medical resources required in parenteral dosing. The pharmacological effects may be due to the active metabolite norketamine, which has been found to be at substantially higher levels via oral dosing, most likely due to first-pass clearance. Despite bioavailability and peak plasma concentrations both being lower than when administered parenterally, evidence suggests that low-dose oral ketamine is clinically effective in treating pain. This may also be due to the actions of norketamine and therefore, its relevance to the mental health context is explored in this narrative review.

Cancer Pain Management: A Narrative Review of Current Concepts, Strategies, and Techniques

Pain is frequently reported during cancer disease, and it still remains poorly controlled in 40% of patients. Recent developments in oncology have helped to better control pain. Targeted treatments may cure cancer disease and significantly increase survival. Therefore, a novel population of patients (cancer survivors) has emerged, also enduring chronic pain (27.6% moderate to severe pain). The present review discusses the different options currently available to manage pain in (former) cancer patients in light of progress made in the last decade. Major progress in the field includes the recent development of a chronic cancer pain taxonomy now included in the International Classification of Diseases (ICD-11) and the update of the WHO analgesic ladder. Until recently, cancer pain management has mostly relied on pharmacotherapy, with opioids being considered as the mainstay. The opioids crisis has prompted the reassessment of opioids use in cancer patients and survivors. This review focuses on the current utilization of opioids, the neuropathic pain component often neglected, and the techniques and non-pharmacological strategies available which help to personalize patient treatment. Cancer pain management is now closer to the management of chronic non-cancer pain, i.e., "an integrative and supportive pain care" aiming to improve patient's quality of life.

Ketamine for Complex Regional Pain Syndrome: A Narrative Review Highlighting Dosing Practices and Treatment Response

This is a narrative review of intravenous ketamine infusions for the treatment of complex regional pain syndrome (CRPS). It briefly covers the definition of CRPS, its epidemiology, and other treatments before introducing ketamine as the article's focus. A summary of ketamine's evidence base and its mechanisms of action is provided. The authors then review ketamine dosages reported in peer-reviewed literature for the treatment of CRPS, and their associated duration of pain relief. The observed response rates to ketamine and predictors of treatment response are also discussed.

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.

A Comparison of the Anti-Anxiety Effects of Oral Ketamine and Fluvoxamine in Children with Separation Anxiety Disorder Manifesting as School Refusal

Background

Children suffer from a high prevalence of anxiety problems that require prompt treatment. It has been demonstrated that ketamine offers rapid anti-anxiety effects. This study aimed to evaluate ketamine's anti-anxiety impact in the treatment of children with school-refusal separation anxiety disorder.

Materials and Methods

In this open-labeled randomized clinical trial, 71 children (6-10 years) diagnosed with school refusal separation anxiety disorder were randomly assigned to two groups; a case group, who received ketamine at a weekly rising dose of 0.1 to 1 mg/kg; the control group treated with Fluvoxamine (25 mg/day), which could increase to 200 mg/day if necessary. The SCARED and CATS questionnaires were used to assess anxiety before treatment, at the 8^th and 16^th weeks of intervention. The data were analyzed using repeated-measures analysis of covariance.

Results

The mean anxiety scores in the eighth week (19.7 ± 16.1) were significantly lower in the ketamine group than before (31.5 ± 10.8). Until the sixteenth week (19.4 ± 14.6), there was no further decrease in scores in the ketamine group, in the fluvoxamine group, pre-treatment scores (36.3 ± 16.5) and eighth week (36.9 ± 16.6) were not significantly different, but scores decreased significantly in a sixteenth week (26.2 ± 12.5).

Conclusion

In first eight weeks of treatment, ketamine was more successful than fluvoxamine at reducing anxiety disorder, considering the emergence of this disorder and the lack of major adverse effects of ketamine, it seems to be beneficial in early phases of treatment. Due to the quick onset of ketamine in future trials, their combination therapy is recommended during the initial weeks of treatment.

Current understanding of the etiology of cyclic vomiting syndrome and therapeutic strategies in its management

INTRODUCTION

Cyclic vomiting syndrome is a chronic debilitating disorder of the gut-brain interaction and is characterized by recurrent episodes of nausea and vomiting.Recent studies indicate that it is common and affects 2% of the US population. Unfortunately, there is significant heterogeneity in the management of these patients in the medical community. This review article aims to bridge this gap and will review the epidemiology and etiology with a focus on management of CVS.

AREAS COVERED

This article reviews the epidemiology, and pathophysiology of CVS and impact on patients. It also discusses management based on recent guidelines based on which is intended for the busy clinician. A literature search was done using PubMed and key words "cyclic vomiting", "management", "etiology", and pathophysiology were used to identify articles of importance.

EXPERT OPINION

CVS is a complex, poorly understood disorder of gut-brain interaction (DGBI) and has a significant negative impact on patients, families and the healthcare system. Recent guidelines recommend a multidisciplinary approach to management using prophylactic therapy in moderate-severe CVS and abortive medication for acute flares. However more research is needed to better understand the pathophysiology and develop targeted therapies for CVS.

Risk Factors for the Development of Neuropsychiatric Adverse Effects in Ketamine-Treated Pain

Ketamine use has increased recently for the management of acute and chronic pain. Ketamine can cause a variety of neuropsychiatric adverse effects, such as hallucinations, dysphoria, and nightmares. The objective of this study was to explore risk factors for the development of neuropsychiatric adverse effects in ketamine-treated pain. This was a retrospective, single-center cohort study of hospitalized patients who received low dose intravenous (IV) ketamine or oral ketamine for pain. Patients who had a neuropsychiatric adverse effect were compared to those who did not. One hundred and seventy-one patients were included, with 155 receiving IV ketamine and 16 receiving oral ketamine. Overall, 50 (29.2%) had a neuropsychiatric adverse effect and 26 (15.2%) required treatment discontinuation. No significant differences were found between patients who tolerated ketamine and those who did not. Patients who had an adverse effect were numerically less likely to receive benzodiazepines (28% vs 39.7%, p = 0.153), as were patients who required discontinuation of ketamine (23.1% vs. 41.4%, p = 0.08). In patients receiving ketamine for pain, predicting who may be more likely to experience neuropsychiatric adverse effects remains difficult. Further research is warranted to determine whether benzodiazepines are safe and effective for mitigating these adverse effects in this setting.

From a Symptom-Based to a Mechanism-Based Pharmacotherapeutic Treatment in Complex Regional Pain Syndrome

Complex regional pain syndrome (CRPS) is a debilitating painful condition of a distal extremity that can develop after tissue damage. CRPS is thought to be a multimechanism syndrome and ideally the most prominent mechanism(s) should be targeted by drugs in an individually tailored manner. This review gives an overview of the action and evidence of current and future pharmacotherapeutic options for CRPS. The available options are grouped in four categories by their therapeutic actions on the CRPS mechanisms, i.e. inflammation, central sensitisation, vasomotor disturbances and motor disturbances. More knowledge about the underlying mechanisms of CRPS helps to specifically target important CRPS mechanisms. In the future, objective biomarkers could potentially aid in selecting appropriate mechanism-based drugs in order to increase the effectiveness of CRPS treatment. Using this approach, current and future pharmacotherapeutic options for CRPS should be studied in multicentre trials to prove their efficacy. The ultimate goal is to shift the symptom-based selection of therapy into a mechanism-based selection of therapy in CRPS.

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.

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

BACKGROUND

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

BACKGROUND

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

AIMS

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

METHOD

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

RESULTS

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

CONCLUSIONS

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

The Effect of Intrathecal Injection of Dextromethorphan on the Experimental Neuropathic Pain Model

Background

Peripheral glucocorticoid receptors (GRs) are altered by peripheral nerve injury and may modulate the development of neuropathic pain. Two central pathogenic mechanisms underlying neuropathic pain are neuroinflammation and N-methyl-D-aspartate receptor (NMDAR)-dependent neural plasticity in the spinal cord.

Objectives

This study examined the effect of the non-competitive NMDAR antagonist dextromethorphan on partial sciatic nerve ligation (PSL)-induced neuropathic pain and the spinal expression of the glucocorticoid receptor (GR).

Methods

Male mice were randomly assigned into a sham group and two groups receiving PSL followed by intrathecal saline vehicle or dextromethorphan (iDMP). Vehicle or iDMP was administered 8 - 14 days after PSL. The hotplate paw-withdrawal latency was considered to measure thermal pain sensitivity. The spinal cord was then sectioned and immunostained for GR.

Results

Thermal hyperalgesia developed similarly in the vehicle and iDMP groups prior to the injections (P = 0.828 and 0.643); however, it was completely mitigated during the iDMP treatment (P < 0.001). GR expression was significantly higher in the vehicle group (55.64 ± 4.50) than in the other groups (P < 0.001). The iDMP group (9.99 ± 0.66) showed significantly higher GR expression than the sham group (6.30 ± 1.96) (P = 0.043).

Conclusions

The suppression of PLS-induced thermal hyperalgesia by iDMP is associated with the downregulation of GR in the spinal cord, suggesting that this analgesic effect is mediated by inhibiting GR-regulated neuroinflammation.

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.

Comeback of ketamine: resurfacing facts and dispelling myths

Initially known as CI-581, ketamine was first synthesized in 1962 as a replacement from phencyclidine. It has since been used as an anesthetic and analgesic. In addition, it has bronchodilating, sedative, and amnestic properties, preserving airway reflexes and sympathetic nervous system tone. Since the discovery of ketamine, it has been a major topic of discussion due to controversies regarding its usage in particular sets of patients. In the past 50 years, despite its potential benefits, it is not commonly used because of concerns of "emergence phenomenon," its use as a substance of abuse, and its systemic side effects. Since 2012, three World Health Organization reviews on ketamine have addressed its international control. Researchers have been studying this wonder drug for a decade worldwide. Many myths of ketamine regarding emergence phenomenon and its use in traumatic brain injury and open eye injury have been disproved in recent times. It is becoming popular in pre-hospital settings, critical care, emergency medicine, low-dose acute pain services, and adjuvant in regional anesthesia techniques. This review highlights the current consensus on the various applications of ketamine in the literature.

Chronic Scrotal Content Pain: a Review of the Literature and Management Schemes

PURPOSE OF REVIEW

Chronic scrotal content pain (CSCP) is a complex condition with multiple etiologies that requires a thorough understanding of its pathophysiology, workup, and treatment options. We performed a comprehensive and contemporary review to augment our current understanding of CSCP.

RECENT FINDINGS

We discuss new advances in CSCP-specific pain questionnaires, modern studies of microscopic spermatic cord denervation and its variations, and novel techniques including electric nerve stimulation and cryoablation in addition to randomized control trials with significant negative findings. We also present literature focusing on the prevention of CSCP secondary to surgical iatrogenic causes. The constantly evolving literature of CSCP has led to the significant evolution in its diagnosis and treatment, from oral medications to salvage options after microscopic spermatic cord denervation. With each advance, we come closer to developing a more thorough, evidence-based algorithm to guide urologists in treatment of CSCP.

Ketamine's dose related multiple mechanisms of actions: Dissociative anesthetic to rapid antidepressant

Ketamine induces safe and effective anesthesia and displays unusual cataleptic properties that gave rise to the term dissociative anesthesia. Since 1970, clinicians only utilized the drug as an anesthetic or analgesic for decades, but ketamine was found to have rapid acting antidepressant effects in 1990s. Accumulated evidence exhibits NMDAR antagonism may not be the only mechanism of ketamine. The contributions of AMPA receptor, mTor signal pathway, monoaminergic system, sigma-1 receptor, cholinergic, opioid and cannabinoid systems, as well as voltage-gated calcium channels and hyperpolarization cyclic nucleotide gated channels are discussed for the antidepressant effects. Also the effects of ketamine's enantiomers and metabolites are reviewed. Furthermore ketamine's anesthetic and analgesic mechanisms are briefly revisited. Overall, pharmacology of ketamine, its enantiomers and metabolites is very unique. Insight into multiple mechanisms of action will provide further development and desirable clinical effects of ketamine.

A revised excretion factor for estimating ketamine consumption by wastewater-based epidemiology - Utilising wastewater and seizure data

The rate of drug excretion (excretion factor) is a critical parameter for monitoring drug consumption in the population by wastewater-based epidemiology (WBE). Previous studies have refined excretion factors for common illicit drugs, such as cocaine, amphetamine, methamphetamine, heroin, to improve the accuracy and reduce uncertainty in back-calculating consumption. Nevertheless, for ketamine, one of the most prevalent psychoactive substances, a careful review of its excretion factors has not been performed due to limited pharmacokinetic data. Here we review WBE studies and seizure data to refine and validate the excretion factors for ketamine and norketamine. The average ketamine/norketamine ratio in wastewater (5.36) was much higher than that found in urine (0.64), which means that the excretion factors derived only from pharmacokinetics data are not appropriate. Based on the comparison of the ratio between estimated consumptions of ketamine and methamphetamine by WBE with their corresponding ratio in official seizure data, a revised WBE excretion factor of 20% was proposed for ketamine following this review and applied to estimate the ketamine consumption in China. The revised estimates of ketamine consumption corresponded well with drug statistics. This suggests that the revised ketamine excretion factor is appropriate for estimating ketamine consumption by WBE. Systematic review of WBE studies is a suitable approach to refine the excretion factors for substances with inadequate pharmacokinetic data.

A Review of Nonanesthetic Uses of Ketamine

Ketamine, a nonselective NMDA receptor antagonist, is used widely in medicine as an anesthetic agent. However, ketamine's mechanisms of action lead to widespread physiological effects, some of which are now coming to the forefront of research for the treatment of diverse medical disorders. This paper aims at reviewing recent data on key nonanesthetic uses of ketamine in the current literature. MEDLINE, CINAHL, and Google Scholar databases were queried to find articles related to ketamine in the treatment of depression, pain syndromes including acute pain, chronic pain, and headache, neurologic applications including neuroprotection and seizures, and alcohol and substance use disorders. It can be concluded that ketamine has a potential role in the treatment of all of these conditions. However, research in this area is still in its early stages, and larger studies are required to evaluate ketamine's efficacy for nonanesthetic purposes in the general population.

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.

A Review of Adjunctive Therapies for Burn Injury Pain During the Opioid Crisis

Opioids are the mainstay of pain management after burn injury. The United States currently faces an epidemic of opioid overuse and abuse, while simultaneously experiencing a nationwide shortage of intravenous narcotics. Adjunctive pain management therapies must be sought and utilized to reduce the use of opioids in burn care to prevent the long-term negative effects of these medications and to minimize the dependence on opioids for analgesia. The purpose of this review was to identify literature on adjunctive pain management therapies that have been demonstrated to reduce pain severity or opioid consumption in adult burn patients. Three databases were searched for prospective studies, randomized controlled trials, and systematic reviews that evaluated adjunctive pain management strategies published between 2008 and 2019 in adult burn patients. Forty-six studies were analyzed, including 24 randomized controlled trials, six crossover trials, and 10 systematic reviews. Various adjunctive pain management therapies showed statistically significant reduction in pain severity. Only one randomized controlled trial on music therapy for acute background pain showed a reduction in opioid use. One cohort study on hypnosis demonstrated reduced opioid use compared with historical controls. We recommend the development of individualized analgesic regimens with the incorporation of adjunctive therapies in order to improve burn pain management in the midst of an abuse crisis and concomitant national opioid shortage.

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.

Expanding Role of NMDA Receptor Antagonists in the Management of Pain

Pain management is complex regardless of whether the pain is acute or chronic in nature or non-cancer or cancer related. In addition, relatively few pain pharmacotherapy options with adequate efficacy and safety data currently exist. Consequently, interest in the role of NMDA receptor antagonists as a pharmacological pain management strategy has surfaced. This narrative review provides an overview of the NMDA receptor and elaborates on the pharmacotherapeutic profile and pain management literature findings for the following NMDA receptor antagonists: ketamine, memantine, dextromethorphan, and magnesium. The literature on this topic is characterized by small studies, many of which exhibit methodological flaws. To date, ketamine is the most studied NMDA receptor antagonist for both acute and chronic pain management. Although further research about NMDA receptor antagonists for analgesia is needed and the optimal dosage/administration regimens for these drugs have yet to be determined, ketamine appears to hold the most promise and may be of particular value in the perioperative pain management realm.

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.

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.

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.

Safety and efficacy of maintenance ketamine treatment in patients with treatment-refractory generalised anxiety and social anxiety disorders

OBJECTIVE

In this maintenance treatment study, we sought to evaluate the effect on anxiety ratings, safety and tolerability of 3 months of weekly ketamine in 20 patients with treatment-refractory DSM IV generalised anxiety disorder (GAD) and/or social anxiety disorder (SAD), and subsequent assessment of remission post-treatment.

METHODS

This was an uncontrolled open-label study in 20 patients who had been responders in an ascending dose ketamine study. The study was undertaken in a university clinic. Patients received one or two weekly ketamine doses of 1 mg/kg injected subcutaneously for 3 months. Data were collected from December 2015-June 2017.

RESULTS

There were 10 women (50%) and 10 men (50%); 15 patients (75%) met criteria for GAD and 18 (90%) for SAD. One hour after dosing, Fear Questionnaire ratings decreased by ~50%, as did Hamilton Anxiety ratings. Clinician Administered Dissociative States Scale mean scores declined over time, from 20 points at week 1 to 8.8 points at week 14. Compared with pre-dose values, mean systolic and diastolic blood pressure increased by ~10 mm Hg at 30 min. The most common adverse events were nausea, dizziness and blurred vision. Of the 20 patients, 18 reported improved social functioning and/or work functioning during maintenance treatment.

CONCLUSIONS

Weekly ketamine dosing was safe and well tolerated, and post-dose dissociative symptoms tended to reduce after repeated dosing. Patients reported marked improvements in functionality and in their personal lives. Maintenance ketamine may be a therapeutic alternative for patients with treatment refractory GAD/SAD.

TRIAL REGISTRATION

http://www.anzctr.org.au/ACTRN12615000617561.

Intranasal Ketamine and Its Potential Role in Cancer-Related Pain

Cancer-related pain continues to be a significant therapeutic challenge, made more difficult by contemporary opioid use and diversion concerns. Conventional treatment using a tiered approach of nonsteroidal antiinflammatory drugs (NSAIDs), opioids, and adjuvant agents is limited; and alternatives are needed for patients with rapidly progressing pain and those who develop hyperalgesia and tolerance to opioids. Ketamine, an N-methyl-d-aspartate (NMDA) selective antagonist, has historically been used for anesthesia in adult and pediatric populations but has also been investigated for depression, bipolar disorder, and general and postoperative pain management. As an analgesic, low-dose ketamine decreases morphine requirements and rates of nausea and vomiting, suggesting a potentially beneficial role in cancer-related pain. Ketamine is typically administered intravenously and has a rapid onset of action with a relatively short half-life (2-3 hours) but is inconvenient for use in an ambulatory setting. Oral bioavailability is low and erratic, limiting application of this route for chronic use. Intranasal administration has a number of potential advantages, including avoidance of first-pass hepatic metabolism, no need for venous access, ability to repeat doses quickly, and rapid absorption. Although early studies of intranasal ketamine are promising in a number of indications, information is more limited in its use as an adjunct in cancer-related pain. We review the background, rationale, pharmacokinetics, and clinical and safety data using intranasal ketamine as an adjunctive agent and its potential in cancer-related pain.

Effects of Ketamine on Icam-1 Expression during Lipopolysaccharide Induced Acute Lung Injury in Rats

Introduction

Intercellular adhesion molecule-1 (ICAM-1) serves very important roles in lung injury, and increases in ICAM-1 are associated with severity of lung injury. We intended to examine whether ketamine could have favourable effects on ICAM-1 expression in lipopolysaccharide (LPS)-induced acute lung injury in the rat.

Methods

The acute lung injury was induced by instilling LPS into the tracheas of 72 anaesthetised rats. The animals were divided into four groups including a sham group with intratracheal saline, an LPS group with intratracheal LPS and intraperitoneal saline, and two ketamine treatment groups with intratracheal LPS and treated with 1 mg/kg or 10 mg/kg doses of intraperitoneal ketamine hydrochloride. Half of the animals were sacrificed at three hours and the remaining animals were sacrificed at six hours. Real time PCR was performed on the lung tissues obtained. Concentration of the soluble ICAM-1 was measured in the bronchoalveolar lavage fluid. Expression of ICAM-1 was measured.

Results

The transcriptional activity of ICAM-1 mRNA increased 9.92 fold in the LPS group compared to the sham group but decreased by 84.1% and 83.3%, respectively, in the 1 and 10 mg/kg ketamine treatment groups. The concentration of soluble ICAM-1 in bronchoalveolar lavage fluid increased 2.23 fold in the LPS group compared to the sham group while decreasing by 75.0% and 74.5% respectively in the 1 mg/kg and 10 mg/kg ketamine treatment groups. The intensity of immunohistochemical staining for ICAM-1 was also decreased in both ketamine treatment groups.

Conclusion

Ketamine attenuates ICAM-1 expression during acute lung injury in rats. (Hong Kong j.emerg.med. 2011;18:397-405)

Ketamine for pain

The efficacy of the N-methyl-D-aspartate receptor antagonist ketamine as an analgesic agent is still under debate, especially for indications such as chronic pain. To understand the efficacy of ketamine for relief of pain, we performed a literature search for relevant narrative and systematic reviews and meta-analyses. We retrieved 189 unique articles, of which 29 were deemed appropriate for use in this review. Ketamine treatment is most effective for relief of postoperative pain, causing reduced opioid consumption. In contrast, for most other indications (that is, acute pain in the emergency department, prevention of persistent postoperative pain, cancer pain, and chronic non-cancer pain), the efficacy of ketamine is limited. Ketamine's lack of analgesic effect was associated with an increase in side effects, including schizotypical effects.

Transition from intravenous to enteral ketamine for treatment of nonconvulsive status epilepticus

Background

Nonconvulsive status epilepticus (NCSE) is a diagnosis that is often challenging and one that may progress to refractory NCSE. Ketamine is a noncompetitive N-methyl-d-aspartate antagonist that increasingly has been used to treat refractory status epilepticus. Current Neurocritical Care Society guidelines recommend intravenous (IV) ketamine infusion as an alternative treatment for refractory status epilepticus in adults. On the other hand, enteral ketamine use in NCSE has been reported in only 6 cases (1 adult and 5 pediatric) in the literature to date.

Case presentation

A 33-year-old woman with a history of poorly controlled epilepsy presented with generalized tonic-clonic seizures, followed by recurrent focal seizures that evolved into NCSE. This immediately recurred within 24 h of a prior episode of NCSE that was treated with IV ketamine. Considering her previous response, she was started again on an IV ketamine infusion, which successfully terminated NCSE. This time, enteral ketamine was gradually introduced while weaning off the IV formulation. Treatment with enteral ketamine was continued for 6 months and then tapered off. There was no recurrence of NCSE or seizures and no adverse events noted during the course of treatment.

Conclusion

This case supports the use of enteral ketamine as a potential adjunct to IV ketamine in the treatment of NCSE, especially in cases without coma. Introduction of enteral ketamine may reduce seizure recurrence, duration of stay in ICU, and morbidity associated with intubation.

Oral Ketamine in Treatment-Resistant Depression: A Clinical Effectiveness Case Series

PURPOSE

The aim of the study was to assess the effectiveness, tolerability, and safety of oral ketamine as an antidepressant treatment in adults with treatment-resistant depression.

METHODS

We reviewed retrospective data on 22 patients with treatment-resistant depression, who failed at least 3 adequate antidepressant treatment trials and 1 adequate trial of repetitive transcranial magnetic stimulation; subsequently, they received open-label treatment with oral ketamine, commenced at a dose of 50 mg every 3 days, titrated up by 25 mg every 3 days, according to response and tolerability. The primary outcome measure was the Beck Depression Inventory II, which was used to rate subjective mood improvement at baseline and then at each follow-up visit. Data about adverse effects related to ketamine and a self-harm risk assessment were also obtained.

FINDINGS

Over the course of treatment, 18% of the patients showed greater than 50% reduction in the Beck Depression Inventory II scores, 14% reported partial improvement in mood symptoms, while 45% had no response to ketamine and 23% showed a mild worsening in their depressive symptoms. The most frequent adverse effects were acute dissociation, dizziness, blurred vision, numbness and sedation. Neither serious adverse effects, nor any cases of abuse or dependence were observed.

CONCLUSIONS

Although this case series found oral ketamine to be safe and well tolerated, the findings also showed rather modest effectiveness of oral ketamine in treatment-resistant depression, with only approximately 30% reporting some benefit and approximately 70% reporting no change or worsening of mood. However, bearing in mind the limitations of this small, open-label case series, further exploration of the effectiveness of oral ketamine is warranted.

Modulation of NMDA Receptor Activity in Fibromyalgia

Activation of the N-methyl-d-aspartate receptor (NMDAR) results in increased sensitivity of spinal cord and brain pathways that process sensory information, particularly those which relate to pain. The NMDAR shows increased activity in fibromyalgia and hence modulation of the NMDAR is a target for therapeutic intervention. A literature review of interventions impacting on the NMDAR shows a number of drugs to be active on the NMDAR mechanism in fibromyalgia patients, with variable clinical effects. Low-dose intravenous ketamine and oral memantine both show clinically useful benefit in fibromyalgia. However, consideration of side-effects, logistics and cost need to be factored into management decisions regarding use of these drugs in this clinical setting. Overall benefits with current NMDAR antagonists appear modest and there is a need for better strategy trials to clarify optimal dose schedules and to delineate potential longer–term adverse events. Further investigation of the role of the NMDAR in fibromyalgia and the effect of other molecules that modulate this receptor appear important to enhance treatment targets in fibromyalgia.

Role of Cytochrome P4502B6 Polymorphisms in Ketamine Metabolism and Clearance

Background

At therapeutic concentrations, cytochrome P4502B6 (CYP2B6) is the major P450 isoform catalyzing hepatic ketamine N-demethylation to norketamine in vitro. The CYP2B6 gene is highly polymorphic. The most common variant allele, CYP2B6*6, is associated with diminished hepatic CYP2B6 expression and catalytic activity compared with wild-type CYP2B6*1/*1. CYP2B6.6, the protein encoded by the CYP2B6*6 allele, and liver microsomes from CYP2B6*6 carriers had diminished ketamine metabolism in vitro. This investigation tested whether humans with the CYP2B6*6 allele would have decreased clinical ketamine metabolism and clearance.

Methods

Thirty volunteers with CYP2B6*1/*1, *1/*6, or *6/*6 genotypes (n = 10 each) received a subsedating dose of oral ketamine. Plasma and urine concentrations of ketamine and the major CYP2B6-dependent metabolites were determined by mass spectrometry. Subjects’ self-assessment of ketamine effects were also recorded. The primary outcome was ketamine N-demethylation, measured as the plasma norketamine/ketamine area under the curve ratio. Secondary outcomes included plasma ketamine enantiomer and metabolite area under the plasma concentration–time curve, maximum concentrations, apparent oral clearance, and metabolite formation clearances.

Results

There was no significant difference between CYP2B6 genotypes in ketamine metabolism or any of the secondary outcome measures. Subjective self-assessment did reveal some differences in energy and level of awareness among subjects.

Conclusions

These results show that while the CYP2B6*6 polymorphism results in diminished ketamine metabolism in vitro, this allelic variant did not affect single, low-dose ketamine metabolism, clearance, and pharmacokinetics in vivo. While in vitro drug metabolism studies may be informative, clinical investigations in general are needed to validate in vitro observations.

Ketamine: 50 Years of Modulating the Mind

Ketamine was introduced into clinical practice in the 1960s and continues to be both clinically useful and scientifically fascinating. With considerably diverse molecular targets and neurophysiological properties, ketamine’s effects on the central nervous system remain incompletely understood. Investigators have leveraged the unique characteristics of ketamine to explore the invariant, fundamental mechanisms of anesthetic action. Emerging evidence indicates that ketamine-mediated anesthesia may occur via disruption of corticocortical information transfer in a frontal-to-parietal (“top down”) distribution. This proposed mechanism of general anesthesia has since been demonstrated with anesthetics in other pharmacological classes as well. Ketamine remains invaluable to the fields of anesthesiology and critical care medicine, in large part due to its ability to maintain cardiorespiratory stability while providing effective sedation and analgesia. Furthermore, there may be an emerging role for ketamine in treatment of refractory depression and Post-Traumatic Stress Disorder. In this article, we review the history of ketamine, its pharmacology, putative mechanisms of action and current clinical applications.

Experience of the use of Ketamine to manage opioid withdrawal in an addicted woman: a case report

BACKGROUND

Opioids are good painkillers, but many patients treated with opioids as painkillers developed a secondary addiction. These patients need to stop misusing opioids, but the mild-to-severe clinical symptoms associated with opioid withdrawal risk increasing their existing pain. In such cases, ketamine, which is used by anaesthetists and pain physicians to reduce opioid medication, may be an effective agent for managing opioid withdrawal.

CASE PRESENTATION

We describe the case of a woman who developed a severe secondary addiction to opioids in the context of lombo-sciatic pain. She presented a severe opioid addiction, and her physicians refused to prescribe such high doses of opioid treatment (oxycontin® extended-release 120 mg daily, oxycodone 60 mg daily, and acetaminophen/codeine 300 mg/25 mg 6 times per day). To assist her with her opioid withdrawal which risked increasing her existing pain, she received 1 mg/kg ketamine oral solution, and two days after ketamine initiation her opioid treatment was gradually reduced. The patient dramatically reduced the dosage of opioid painkillers and ketamine was withdrawn without any withdrawal symptoms.

CONCLUSION

Ketamine displays many interesting qualities for dealing with all symptoms relating to opioid withdrawal. Accordingly, it could be used instead of many psychotropic treatments, which interact with each other, to help with opioid withdrawal. However, the literature describes addiction to ketamine. All in all, although potentially addictive, ketamine could be a good candidate for the pharmacological management of opioid withdrawal.