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

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.