Synergistic Effect of Ketamine and Buprenorphine Observed in the Treatment of Buprenorphine Precipitated Opioid Withdrawal in a Patient With Fentanyl Use

Ketamine: An emerging agent in the management of neuropsychiatric disorders

Ketamine's unique pharmacological profile, safety, modulation of multiple neurotransmitter systems, and ability to produce neuroplastic changes make it a subject of study with implications for a wide range of neuropsychiatric disorders beyond its traditional use as an anesthetic agent. This article aims to provide an overview of the pharmacology of ketamine and briefly discuss its emerging use in treating: substance use disorders (alcohol, cannabis, cocaine, and opioids); withdrawal syndromes (opioid and alcohol); acute and chronic pain syndromes; and severe psychomotor agitation. Ketamine for the treatment of depression and suicidality is well established; however, the focus of this paper is to outline less common indications.

Ketamine and Hydroxynorketamine as Novel Pharmacotherapies for the Treatment of Opioid Use Disorders

Opioid use disorder (OUD) has reached epidemic proportions, with many countries facing high levels of opioid use and related fatalities. Although currently prescribed medications for OUD are considered lifesaving, they inadequately address negative affect and cognitive impairment, resulting in high relapse rates to nonmedical opioid use even years after drug cessation (protracted abstinence). Evidence supports the notion that ketamine, an anesthetic and rapid-acting antidepressant drug, holds promise as a candidate for OUD treatment, including the management of acute withdrawal somatic symptoms, negative affect during protracted opioid abstinence, and prevention of retaking nonmedical opioids. In this review, we comprehensively discuss preclinical and clinical research that has evaluated ketamine and its metabolites as potential novel therapeutic strategies for treating OUD. Furthermore, we examine evidence that supports the relevance of the molecular targets of ketamine and its metabolites in relation to their potential effects and therapeutic outcomes in OUD. Overall, existing evidence demonstrates that ketamine and its metabolites can effectively modulate pathophysiological processes affected in OUD, suggesting a promising therapeutic role in the treatment of OUD and the prevention of return to opioid use during abstinence.

The therapeutic effects of psychedelics for opioid use disorder: A systematic review of clinical studies

Opioid-related overdose deaths have reached record high levels, and novel treatments for opioid use disorder (OUD) are needed. The three United States Food and Drug Administration (FDA)-approved medications for OUD function primarily at the mu-opioid receptor. While these remain the gold-standard treatment for OUD, they have shortcomings and treatment options separate from the opioid receptor system deserve attention. Preclinical, clinical, and naturalistic studies of psychedelics have shown some evidence that they may reduce opioid and other substance use. Here, we present the results of a systematic review of clinical studies investigating the therapeutic applications of psychedelics for OUD to describe the current state of the literature and guide future clinical study design in this area. Findings indicate few studies completed using serotonergic psychedelics, with most investigating ibogaine or ketamine. In addition, findings are limited by many studies of weak design focused on opioid withdrawal, and few double-blind or placebo-controlled trials with considerable methodological heterogeneity making comparisons difficult across compounds. Most studies were found to have a high risk of bias mostly related to lack of randomization, blinding, and blinding of assessment outcomes. We outline these limitations and steps towards improving the quality of future studies of psychedelics for OUD.

A Scoping Review and Consensus Recommendations for Emergency Medical Services Buprenorphine (EMS-Bupe) Programs

OBJECTIVES

Emergency Medical Services (EMS) agencies are beginning to provide low-barrier access to treatment for opioid use disorder (OUD) through the development of EMS buprenorphine (EMS-Bupe) programs. However, evidence-based practices for these programs are lacking. Our aim was to review the current literature on EMS and emergency department (ED) based buprenorphine treatment programs to provide consensus recommendations on the EMS-Bupe program development.

METHODS

We performed a scoping review of EMS-Bupe programs and ED medication for OUD (MOUD) programs. We searched Ovid MEDLINE(R), Embase.com, Cochrane Central Register of Controlled Trials and Web of Science (Science Citation Index) for English language articles and abstracts. Additional articles/abstracts as identified independently by coauthors were added. Recommendations were generated through consensus based on the findings of the scoping review and other relevant literature.

RESULTS

We identified a total of 9 EMS-Bupe articles/abstracts and 21 ED MOUD abstract, representing 5 EMS-Bupe programs in 4 states. There was significant variability between programs, from infrastructure, medication dosing, and retention rates. Results and recommendations were grouped into 8 categories: EMS program infrastructure, withdrawal classification thresholds, EMS protocol inclusion/exclusion criteria, buprenorphine dosing and adjunct medications, EMS disposition and scene times, EMS clinician training, referrals, and EMS data collection and quality management.

CONCLUSIONS

The EMS-Bupe program data are limited but show important variability. In general, we recommend that programs respond to community needs by establishing relationships with local resources. We also favor protocols that increase patient eligibility and treatment retention. Lastly, programs should consider low-barrier, patient-centered strategies aimed at preventing gaps in treatment.

Challenges with current diagnosis and treatment strategies for precipitated opioid withdrawal in the emergency department and the role of the pharmacist

PURPOSE

To demonstrate the challenges with current diagnosis and treatment strategies for precipitated opioid withdrawal secondary to naloxone the emergency department (ED) setting and describe the role of the emergency medicine (EM) pharmacist in its management.

SUMMARY

There are no standardized criteria to define precipitated opioid withdrawal syndrome, so the diagnosis is typically based on sentinel signs and symptoms and time course. Complicating factors include a positive urine toxicology screen for nonopioid substances, comorbidities and associated medications prior to admission, medications given in the ED, and a fluctuating patient course during the ED stay that likely involves all these issues. Although buprenorphine is frequently recommended as the primary treatment for precipitated withdrawal, its use can be complicated if patients are on methadone maintenance or other long-acting opioids. The EM pharmacist plays a key role in managing patients with precipitated withdrawal.

CONCLUSION

Practice changes related to the diagnosis and treatment of opioid use disorder (OUD) with precipitated withdrawal in the ED are needed. EM pharmacists as part of the interprofessional care team have an important role in the management of patients with OUD, including those patients undergoing possible precipitated withdrawal.

Nonopioid medications for managing opioid withdrawal in acute care settings: A scoping review

PURPOSE

There are hospitalized patients with chronic opioid use who will experience signs and symptoms of opioid withdrawal who were not on medications for opioid use disorder (OUD) prior to admission, do not want to start or are unable to start medications for OUD during admission, and want to limit or avoid the use of opioids. The purpose of this scoping review was to assess the potential effectiveness and safety of using non-opioid agents for managing acute opioid withdrawal in acute care settings.

METHODS

PubMed (inception to 2024), Embase (inception to 2024), and Cochrane Library (inception to 2024) were the databases evaluated for the literature search. Bibliographies of full-text articles were reviewed for additional relevant papers.

RESULTS

Twenty-eight studies evaluating nonopioid agents for managing acute opioid withdrawal were identified in the literature search. The agents could be divided into 4 broad mechanistic categories: α-adrenergic receptor agonists, N-methyl-d-aspartate (NMDA) antagonists, gamma-aminobutyric acid (GABA) modulators, and serotonergic agents. Of these drug classes, the available literature suggests the α-adrenergic receptor agonists clonidine and lofexidine have the best evidence of efficacy as alternative agents for acute opioid withdrawal, although the majority of studies comparing such agents to opioids for opioid withdrawal were conducted well before the rise in synthetic opioid overdose deaths and have other methodologic issues that limit firm conclusions concerning efficacy and, particularly, safety.

CONCLUSION

For the nonopioid alternative agents that have been studied for acute opioid withdrawal, there is more evidence supporting the efficacy of α-adrenergic receptor agonists as opposed to NMDA antagonists, GABA modulators, or sertonergic agents; however, more research is needed regarding the efficacy and safety of nonopioid alternatives for acute opioid withdrawal in order to better guide clinical decision-making.

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.

Esketamine in depression: putative biomarkers from clinical research

The discovery of racemic (R, S)-ketamine as a rapid-acting antidepressant and the subsequent FDA approval of its (S)-enantiomer, esketamine, for treatment-resistant depression (TRD) are significant advances in the development of novel neuropsychiatric therapeutics. Esketamine is now recognized as a powerful tool for addressing persistent symptoms of TRD compared to traditional oral antidepressants. However, research on biomarkers associated with antidepressant response to esketamine has remained sparse and, to date, has been largely extrapolated from racemic ketamine studies. Genetic, proteomic, and metabolomic profiles suggest that inflammation and mitochondrial function may play a role in esketamine's antidepressant effects, though these preliminary results require verification. In addition, neuroimaging research has consistently implicated the prefrontal cortex, striatum, and anterior cingulate cortex in esketamine's effects. Esketamine also shows promise in perioperative settings for reducing depression and anxiety, and these effects appear to correlate with increased peripheral biomarkers such as brain-derived neurotrophic factor and serotonin. Further indications are likely to be identified with the continued repurposing of racemic ketamine, providing further opportunity for biomarker study and mechanistic understanding of therapeutic effects. Novel methodologies and well-designed biomarker-focused clinical research trials are needed to more clearly elucidate esketamine's therapeutic actions as well as biologically identify those most likely to benefit from this agent, allowing for the improved personalization of antidepressant treatment.

Cold nociception as a measure of hyperalgesia during spontaneous heroin withdrawal in mice

Opioids are powerful analgesic drugs that are used clinically to treat pain. However, chronic opioid use causes compensatory neuroadaptations that result in greater pain sensitivity during withdrawal, known as opioid withdrawal-induced hyperalgesia (OWIH). Cold nociception tests are commonly used in humans, but preclinical studies often use mechanical and heat stimuli to measure OWIH. Thus, further characterization of cold nociception stimuli is needed in preclinical models. We assessed three cold nociception tests-thermal gradient ring (5-30 °C, 5-50 °C, 15-40 °C, and 25-50 °C), dynamic cold plate (4 °C to -1 °C at -1 °C/min, -1 °C to 4 °C at +1 °C/min), and stable cold plate (10 °C, 6 °C, and 2 °C)-to measure hyperalgesia in a mouse protocol of heroin dependence. On the thermal gradient ring, mice in the heroin withdrawal group preferred warmer temperatures, and the results depended on the ring's temperature range. On the dynamic cold plate, heroin withdrawal increased the number of nociceptive responses, with a temperature ramp from 4 °C to -1 °C yielding the largest response. On the stable cold plate, heroin withdrawal increased the number of nociceptive responses, and a plate temperature of 2 °C yielded the most significant increase in responses. Among the three tests, the stable cold plate elicited the most robust change in behavior between heroin-dependent and nondependent mice and had the highest throughput. To pharmacologically characterize the stable cold plate test, we used μ-opioid and non-opioid receptor-targeting drugs that have been previously shown to reverse OWIH in mechanical and heat nociception assays. The full μ-opioid receptor agonist methadone and μ-opioid receptor partial agonist buprenorphine decreased OWIH, whereas the preferential μ-opioid receptor antagonist naltrexone increased OWIH. Two N-methyl-d-aspartate receptor antagonists (ketamine, MK-801), a corticotropin-releasing factor 1 receptor antagonist (R121919), a β2-adrenergic receptor antagonist (butoxamine), an α2-adrenergic receptor agonist (lofexidine), and a 5-hydroxytryptamine-3 receptor antagonist (ondansetron) had no effect on OWIH. These data demonstrate that the stable cold plate at 2 °C yields a robust, reliable, and concise measure of OWIH that is sensitive to opioid agonists.

Ketamine in neuropsychiatric disorders: an update

The discovery of ketamine as a rapid-acting antidepressant led to a new era in the development of neuropsychiatric therapeutics, one characterized by an antidepressant response that occurred within hours or days rather than weeks or months. Considerable clinical research supports the use of-or further research with-subanesthetic-dose ketamine and its (S)-enantiomer esketamine in multiple neuropsychiatric disorders including depression, bipolar disorder, anxiety spectrum disorders, substance use disorders, and eating disorders, as well as for the management of chronic pain. In addition, ketamine often effectively targets symptom domains associated with multiple disorders, such as anxiety, anhedonia, and suicidal ideation. This manuscript: 1) reviews the literature on the pharmacology and hypothesized mechanisms of subanesthetic-dose ketamine in clinical research; 2) describes similarities and differences in the mechanism of action and antidepressant efficacy between racemic ketamine, its (S) and (R) enantiomers, and its hydroxynorketamine (HNK) metabolite; 3) discusses the day-to-day use of ketamine in the clinical setting; 4) provides an overview of ketamine use in other psychiatric disorders and depression-related comorbidities (e.g., suicidal ideation); and 5) provides insights into the mechanisms of ketamine and therapeutic response gleaned from the study of other novel therapeutics and neuroimaging modalities.

Suspected Buprenorphine-Precipitated Opioid Withdrawal following Intercourse: A Case Report

Buprenorphine, a partial mu-opioid receptor agonist, is a commonly prescribed medication for opioid use disorder (OUD). There is evidence that drugs may enter the male genitourinary tract by an ion-trapping process, based on the lipid solubility and degree of ionization (1). While little is known about the pharmacokinetics of drugs in seminal fluid, pH is thought to play an integral role. Limited evidence exists surrounding cervical absorption of drugs via seminal fluid transmission. This also prompts survey of the frequency of this event and the influence on treatment within this population.

Early emergency department experience with 7-day extended-release injectable buprenorphine for opioid use disorder

As the opioid overdose epidemic escalates, there is an urgent need for treatment innovations to address both patient and clinician barriers when initiating buprenorphine in the emergency department (ED). These include insurance status, logistical challenges such as the ability to fill a prescription and transportation, concerns regarding diversion, and availability of urgent referral sites. Extended-release buprenorphine (XR-BUP) preparations such as a new 7-day injectable could potentially solve some of these issues. We describe the pharmacokinetics of a new 7-day XR-BUP formulation and the feasibility of its use in the ED setting. We report our early experiences with this medication (investigational drug CAM2038), in the context of an ongoing clinical trial entitled Emergency Department-Initiated BUP VAlidaTION (ED INNOVATION), to inform emergency clinicians as they consider incorporating this medication into their practice. The medication was approved by the European Medicines Agency in 2018 and the U.S. Food and Drug Administration in 2023 for those 18 years or older for the treatment of moderate to severe opioid use disorder (OUD). We report our experience with approximately 800 ED patients with OUD who received the 7-day XR-BUP preparation in the ED between June 2020 and July 2023.

The effects of (2R,6R)-hydroxynorketamine on oxycodone withdrawal and reinstatement

Despite the thousands of lives lost during the ongoing opioid crisis, a scarcity of new and effective clinical treatments for opioid use disorder (OUD) remains. To address this unmet need, some researchers have turned to dissociative and psychedelic drugs to treat multiple psychiatric conditions. In particular, low doses of ketamine have been shown to attenuate opioid withdrawal and drug use in clinical and preclinical studies. However, ketamine has misuse liability and dissociative side effects that may limit its widespread application as a treatment for OUD. More recently, (2R,6R)-hydroxynorketamine (HNK), a ketamine metabolite that lacks misuse potential, has gained attention for its effectiveness in depression and stress models. To uncover its role in OUD, we tested the time-dependent effects of (2R,6R)-HNK on oxycodone withdrawal and reinstatement of oxycodone conditioned place preference (CPP). In male and female oxycodone-dependent mice, we found that 24h pretreatment with (2R,6R)-HNK (10 or 30mg/kg, s.c.) reduced the frequency of withdrawal-like behaviors and global withdrawal scores during naloxone-precipitated withdrawal, whereas 1h pretreatment with (2R,6R)-HNK only reduced paw tremors and the sum of global withdrawal scores but not GWS Z-scores. In other experiments, both 1h and 24h pretreatment with (2R,6R)-HNK (30mg/kg, s.c.) blocked drug-induced reinstatement of oxycodone CPP. Finally, we found (2R,6R)-HNK (30mg/kg, sc) had no effect on locomotor activity and thigmotaxis. Together, these results indicate that acute (2R,6R)-HNK has efficacy in some preclinical models of OUD without producing locomotor or anxiety-like side effects.

ASAM Clinical Considerations: Buprenorphine Treatment of Opioid Use Disorder for Individuals Using High-potency Synthetic Opioids

ABSTRACT

Treatment of opioid use disorder (OUD) with buprenorphine has evolved considerably in the last decade as the scale of the OUD epidemic has increased along with the emergence of high-potency synthetic opioids (HPSOs) and stimulants in the drug supply. These changes have outpaced the development of prospective research, so a clinical consideration document based on expert consensus is needed to address pressing clinical questions. This clinical considerations document is based on a narrative literature review and expert consensus and will specifically address considerations for changes to the clinical practice of treatment of OUD with buprenorphine for individuals using HPSO. An expert panel developed 6 key questions addressing buprenorphine initiation, stabilization, and long-term treatment for individuals with OUD exposed to HPSO in various treatment settings. Broadly, the clinical considerations suggest that individualized strategies for buprenorphine initiation may be needed. The experience of opioid withdrawal negatively impacts the success of buprenorphine treatment, and attention to its management before and during buprenorphine initiation should be proactively addressed. Buprenorphine dose and dosing frequency should be individualized based on patients' treatment needs, the possibility of novel components in the drug supply should be considered during OUD treatment, and all forms of opioid agonist treatment should be offered and considered for patients. Together, these clinical considerations attempt to be responsive to the challenges and opportunities experienced by frontline clinicians using buprenorphine for the treatment of OUD in patients using HPSOs and highlight areas where prospective research is urgently needed.

Case Report: Buprenorphine-precipitated fentanyl withdrawal treated with high-dose buprenorphine

Background: Buprenorphine, a partial agonist of the mu-opioid receptor, is an increasingly prescribed medication for maintenance treatment of opioid use disorder. When this medication is taken in the context of active opioid use, precipitated withdrawal can occur, leading to acute onset of opioid withdrawal symptoms. Fentanyl complicates use of buprenorphine, as it slowly releases from body stores and can lead to higher risk of precipitated withdrawal. Objectives: Describe the successful management of buprenorphine precipitated opioid withdrawal from fentanyl with high doses of buprenorphine. We seek to highlight how no adverse effects occurred in this patient and illustrate his stable transition to outpatient treatment. Case report: We present the case of a patient with severe opioid use disorder who presented in moderately severe opioid withdrawal after taking non-prescribed buprenorphine-naloxone which precipitated opioid withdrawal from daily fentanyl use. He was treated with high doses of buprenorphine, 148 mg over the first 48 hours, averaging 63 mg per day over four days. The patient reported rapid improvement in withdrawal symptoms without noted side effects and was able to successfully taper to 16 mg twice daily by discharge. Conclusions: This case demonstrates the safety and effectiveness of buprenorphine at high doses for treatment of precipitated withdrawal. While other options include symptomatic withdrawal management, initiating methadone or less researched options like ketamine, utilizing buprenorphine can preserve or re-establish confidence in this life-saving medication. This case also increases the previously documented upper boundary on buprenorphine dosing for withdrawal and should provide additional confidence in its use.

Hospitalist perspectives on buprenorphine treatment for inpatients with opioid use disorder

Background

Patients with opioid use disorder (OUD) have high hospital admission rates. Hospitalists, clinicians that work in inpatient medical settings, may have a unique opportunity to intervene on behalf of these patients, yet their experience with and attitudes towards treating patients with OUD need further exploration.

Methods

We conducted qualitative analysis of 22 semi-structured interviews with hospitalists between January and April 2021 in Philadelphia, PA. Participants were hospitalists in one major metropolitan university hospital and one urban community hospital in a city with a high prevalence of OUD and overdose deaths. Participants were asked about their experiences, successes, and difficulties in treating hospitalized patients with OUD.

Results

Twenty-two hospitalists were interviewed. Participants were majority female (14, 64%) and White (16, 73%). We identified the following common themes: lack of training/experience with OUD, a lack of community OUD treatment infrastructure, a lack of inpatient OUD/withdrawal treatment resources, the "X-waiver" as a barrier to prescribing buprenorphine, the "ideal" patient to start on buprenorphine, and the hospital as an ideal intervention setting.

Conclusions

Hospitalization due to acute illness or complication of drug use represents a potential intervention point to initiate treatment for patients with OUD. While hospitalists exhibit willingness to prescribe medications, provide harm reduction education, and link patients to outpatient addiction treatment, they identify training and infrastructure barriers that must first be addressed.

"Just give them a choice": Patients' perspectives on starting medications for opioid use disorder in the ED

OBJECTIVES

Medications for opioid use disorder (MOUD) prescribed in the emergency department (ED) have the potential to save lives and help people start and maintain recovery. We sought to explore patient perspectives regarding the initiation of buprenorphine and methadone in the ED with the goal of improving interactions and fostering shared decision making (SDM) around these important treatment options.

METHODS

We conducted semistructured interviews with a purposeful sample of people with opioid use disorder (OUD) regarding ED visits and their experiences with MOUD. The interview guide was based on the Ottawa Decision Support Framework, a framework for examining decisional needs and tailoring decisional support, and the research team's experience with MOUD and SDM. Interviews were recorded, transcribed, and analyzed in an iterative process using both the Ottawa Framework and a social-ecological framework. Themes were identified and organized and implications for clinical care were noted and discussed.

RESULTS

Twenty-six participants were interviewed, seven in person in the ED and 19 via video conferencing software. The majority had tried both buprenorphine and methadone, and almost all had been in an ED for an issue related to opioid use. Participants reported social, pharmacological, and emotional factors that played into their decision making. Regarding buprenorphine, they noted advantages such as its efficacy and logistical ease and disadvantages such as the need to wait to start it (risk of precipitated withdrawal) and that one could not use other opioids while taking it. Additionally, participants felt that: (1) both buprenorphine and methadone should be offered; (2) because "one person's pro is another person's con," clinicians will need to understand the facets of the options; (3) clinicians will need to have these conversations without appearing judgmental; and (4) many patients may not be "ready" for MOUD, but it should still be offered.

CONCLUSIONS

Although participants were supportive of offering buprenorphine in the ED, many felt that methadone should also be offered. They felt that treatment should be tailored to an individual's needs and circumstances and clarified what factors might be important considerations for people with OUD.