Extended-Release 7-Day Injectable Buprenorphine for Patients With Minimal to Mild Opioid Withdrawal.

Importance: Buprenorphine is an effective yet underused treatment for opioid use disorder (OUD). Objective: To evaluate the feasibility (acceptability, tolerability, and safety) of 7-day injectable extended-release buprenorphine in patients with minimal to mild opioid withdrawal. Design, Setting, and Participants: This nonrandomized trial comprising 4 emergency departments in the Northeast, mid-Atlantic, and Pacific geographic areas of the US included adults aged 18 years or older with moderate to severe OUD and Clinical Opiate Withdrawal Scale (COWS) scores less than 8 (minimal to mild), in which scores range from 0 to 7, with higher scores indicating increasing withdrawal. Exclusion criteria included methadone-positive urine, pregnancy, overdose, or required admission. Outcomes were assessed at baseline, daily for 7 days by telephone surveys, and in person at 7 days. Patient recruitment occurred between July 13, 2020, and May 25, 2023. Intervention: Injection of a 24-mg dose of a weekly extended-release formulation of buprenorphine (CAM2038) and referral for ongoing OUD care. Main Outcomes and Measures: Primary feasibility outcomes included the number of patients who (1) experienced a 5-point or greater increase in the COWS score or (2) transitioned to moderate or greater withdrawal (COWS score ≥13) within 4 hours of extended-release buprenorphine or (3) experienced precipitated withdrawal within 1 hour of extended-release buprenorphine. Secondary outcomes included injection pain, satisfaction, craving, use of nonprescribed opioids, adverse events, and engagement in OUD treatment. Results: A total of 100 adult patients were enrolled (mean [SD] age, 36.5 [8.7] years; 72% male). Among the patients, 10 (10.0% [95% CI, 4.9%-17.6%]) experienced a 5-point or greater increase in COWS and 7 (7.0% [95% CI, 2.9%-13.9%]) transitioned to moderate or greater withdrawal within 4 hours, and 2 (2.0% [95% CI, 0.2%-7.0%]) experienced precipitated withdrawal within 1 hour of extended-release buprenorphine. A total of 7 patients (7.0% [95% CI, 2.9%-13.9%]) experienced precipitated withdrawal within 4 hours of extended-release buprenorphine, which included 2 of 63 (3.2%) with a COWS score of 4 to 7 and 5 of 37 (13.5%) with a COWS score of 0 to 3. Site pain scores (based on a total pain score of 10, in which 0 indicated no pain and 10 was the worst possible pain) after injection were low immediately (median, 2.0; range, 0-10.0) and after 4 hours (median, 0; range, 0-10.0). On any given day among those who responded, between 29 (33%) and 31 (43%) patients reported no cravings and between 59 (78%) and 75 (85%) reported no use of opioids; 57 patients (60%) reported no days of opioid use. Improving privacy (62%) and not requiring daily medication (67%) were deemed extremely important. Seventy-three patients (73%) were engaged in OUD treatment on day 7. Five serious adverse events occurred that required hospitalization, of which 2 were associated with medication. Conclusions and Relevance: This nonrandomized trial of the feasibility of a 7-day buprenorphine injectable in patients with minimal to mild opioid withdrawal (COWS scores, 0-7) found the formulation to be acceptable, well tolerated, and safe in those with COWS scores of 4 to 7. This new medication formulation could substantially increase the number of patients with OUD receiving buprenorphine. Trial Registration: ClinicalTrials.gov Identifier: NCT04225598.

Scaling Emergency Department Opioid Use Disorder Treatment Across California to Reduce Overdose Deaths, 2019-2023.

Since April 2019, CA Bridge has worked with emergency departments (EDs) in diverse geographic and emergency care settings across California to scale up low-threshold buprenorphine access, patient navigation programs, harm reduction services, and take-home naloxone. Between April 2019 and June 2023, 268 (81.0%) of 331 acute care hospitals in California received funding and technical assistance from CA Bridge and completed data reporting. These hospitals provided navigation services during 279 025 patient encounters and gave patients buprenorphine in 89 549 ED visits. (Am J Public Health. Published online ahead of print June 27, 2024:e1-e5. https://doi.org/10.2105/AJPH.2024.307710).

A qualitative assessment of emergency physicians' experiences with robust emergency department buprenorphine bridge programs.

OBJECTIVES: Emergency departments (EDs) are a critical point of entry into treatment for patients struggling with opioid use disorder (OUD). When initiated in the ED, buprenorphine is associated with increased addiction treatment engagement at 30 days when initiated. Despite this association, it has had slow adoption. The barriers to ED buprenorphine utilization are well documented; however, the benefits of prescribing buprenorphine for emergency physicians (EPs) have not been explored. This study utilized semistructured interviews to explore and understand how EPs perceive their experiences working in EDs that have successfully implemented ED bridge programs (EDBPs) for patients with OUD. METHODS: Semistructured interviews were conducted with EPs from four geographically diverse academic hospitals with established EDBPs. Interviews were recorded and transcribed, and emergent themes were identified using codebook thematic analysis. Analysis credibility and transparency were confirmed with peer debriefing. RESULTS: Twenty-two interviews were conducted across the four sites. Three key themes were constructed during the analyses: (1) provided EPs agency; (2) transformed EPs' emotions, attitudes, and behaviors related to treating patients with OUD; and (3) improved EPs' professional quality of life. CONCLUSIONS: Participants in this study reported several common themes related to participation in their hospital's BP. Overall our results suggest that physicians who participate in EDBPs may feel a renewed sense of fulfillment and purpose in their personal and professional lives. These positive changes may lead to increased job satisfaction in hospitals that have successfully launched EDBP.

Emergency Department Access to Buprenorphine for Opioid Use Disorder.

Importance: Although substantial evidence supports buprenorphine for treatment of opioid use disorder (OUD) in controlled trials, prospective study of patient outcomes in clinical implementation of emergency department (ED) buprenorphine treatment is lacking. Objective: To examine the association between buprenorphine treatment in the ED and follow-up engagement in OUD treatment 1 month later. Design, Setting, and Participants: This multisite cohort study was conducted in 7 California EDs participating in a statewide implementation project to improve access to buprenorphine treatment. The study population included ED patients aged at least 18 years identified with OUD between April 1, 2021, and June 30, 2022. Data analysis was performed in October 2023. Exposure: All participants were offered buprenorphine treatment for OUD (either in ED administration, prescription, or both), the uptake of which was examined as the exposure of interest. Main Outcomes and Measures: The primary outcome was engagement in OUD treatment 30 days after the ED visit, determined by patient report or clinical documentation. The association of ED buprenorphine treatment with subsequent OUD treatment engagement was estimated using hierarchical generalized linear models. Results: This analysis included 464 ED patients with OUD. Their median age was 36.0 (IQR, 29.0-38.7) years, and most were men (343 [73.9%]). With regard to race and ethnicity, 64 patients (13.8%) self-identified as non-Hispanic Black, 183 (39.4%) as Hispanic, and 185 as non-Hispanic White (39.9%). Most patients (396 [85.3%]) had Medicaid insurance, and more than half (262 [57.8%]) had unstable housing. Self-reported fentanyl use (242 [52.2%]) and a comorbid mental health condition (328 [71.5%]) were common. Interest in buprenorphine treatment was high: 398 patients (85.8%) received buprenorphine treatment; 269 (58.0%) were administered buprenorphine in the ED and 339 (73.1%) were prescribed buprenorphine. With regard to OUD treatment engagement at 30 days after the ED visit, 198 participants (49.7%) who received ED buprenorphine treatment remained engaged compared with 15 participants (22.7%) who did not receive ED buprenorphine treatment. An association of ED buprenorphine treatment with subsequent OUD treatment engagement at 30 days was observed (adjusted risk ratio, 1.97 [95% CI, 1.27-3.07]). Conclusions and Relevance: The findings of this cohort study suggest that among patients with OUD presenting to EDs implementing low-threshold access to medications for OUD, buprenorphine treatment was associated with a substantially higher likelihood of follow-up treatment engagement 1 month later. Future research should investigate techniques to optimize both the uptake and effectiveness of buprenorphine initiation in low-threshold settings such as the ED.

Leveraging a Learning Collaborative Model to Develop and Pilot Quality Measures to Improve Opioid Prescribing in the Emergency Department.

The American College of Emergency Physicians (ACEP) Emergency Medicine Quality Network (E-QUAL) Opioid Initiative was launched in 2018 to advance the dissemination of evidence-based resources to promote the care of emergency department (ED) patients with opioid use disorder. This virtual platform-based national learning collaborative includes a low-burden, structured quality improvement project, data benchmarking, tailored educational content, and resources designed to support a nationwide network of EDs with limited administrative and research infrastructure. As a part of this collaboration, we convened a group of experts to identify and design a set of measures to improve opioid prescribing practices to provide safe analgesia while reducing opioid-related harms. We present those measures here, alongside initial performance data on those measures from a sample of 370 nationwide community EDs participating in the 2019 E-QUAL collaborative. Measures include proportion of opioid administration in the ED, proportion of alternatives to opioids as first-line treatment, proportion of opioid prescription, opioid pill count per prescription, and patient medication safety education among ED visits for atraumatic back pain, dental pain, or headache. The proportion of benzodiazepine and opioid coprescribing for ED visits for atraumatic back pain was also evaluated. This project developed and effectively implemented a collection of 6 potential measures to evaluate opioid analgesic prescribing across a national sample of community EDs, representing the first feasibility assessment of opioid prescribing-related measures from rural and community EDs.

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.

URINE TOXICOLOGY PROFILES OF EMERGENCY DEPARTMENT PATIENTS WITH UNTREATED OPIOID USE DISORDER: A MULTI-SITE VIEW.

BACKGROUND: Opioid overdose deaths in 2021 were the highest ever, driven by fentanyl and polysubstance use. OBJECTIVE: The aim of the study was to characterize drug use, assessed by urine drug screens (UDSs), in patients with untreated opioid use disorder (OUD) presenting to 28 emergency departments (EDs) nationally and by region. METHODS: We analyzed UDSs from patients enrolled in the CTN-0099 ED-INNOVATION (Emergency Department-Initiated Buprenorphine Validation) trial between July 12, 2020 and March 9, 2022. Participants were adult ED patients with OUD not engaged in addiction treatment with a UDS positive for an opioid, but negative for methadone. Sites were divided into "East" and "West" regions. RESULTS: A UDS was available for all 925 enrolled participants, 543 from East and 382 from West. Fentanyl was in 702 specimens (76%) (n = 485 [89%] East vs. n = 217 [57%] West; p < 0.01) and was the only opioid in 269 (29%). After fentanyl, the most common opioids were morphine (presumably heroin; n = 411 [44%]; n = 192 [35%] East vs. n = 219 [57%] West; p < 0.01) and buprenorphine (n = 329 [36%]; n = 186 [35%] East vs. n = 143 [37%] West; p = 0.32). The most common drugs found with opioids were stimulants (n = 545 [59%]), tetrahydrocannabinol (n = 417 [45%]), and benzodiazepines (n = 151 [16%]). Amphetamine-type stimulants were more common in West (n = 209 [55%] vs. East (n = 125 [23%]). Cocaine was more common in East (n = 223 [41%]) vs. West (n = 82 [21%]). The presence of multiple drugs was common (n = 759 [82%]). CONCLUSIONS: Most participants had UDS specimens containing multiple substances; a high proportion had fentanyl, stimulants, and buprenorphine. Regional differences were noted. Given the increased risk of death with fentanyl and polysubstance use, ED providers should be providing risk reduction counseling, treatment, and referral.

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.

National Institute on Drug Abuse Clinical Trials Network Meeting Report: Advancing Emergency Department Initiation of Buprenorphine for Opioid Use Disorder.

Opioid use disorder and opioid overdose deaths are a major public health crisis, yet highly effective evidence-based treatments are available that reduce morbidity and mortality. One such treatment, buprenorphine, can be initiated in the emergency department (ED). Despite evidence of efficacy and effectiveness for ED-initiated buprenorphine, universal uptake remains elusive. On November 15 and 16, 2021, the National Institute on Drug Abuse Clinical Trials Network convened a meeting of partners, experts, and federal officers to identify research priorities and knowledge gaps for ED-initiated buprenorphine. Meeting participants identified research and knowledge gaps in 8 categories, including ED staff and peer-based interventions; out-of-hospital buprenorphine initiation; buprenorphine dosing and formulations; linkage to care; strategies for scaling ED-initiated buprenorphine; the effect of ancillary technology-based interventions; quality measures; and economic considerations. Additional research and implementation strategies are needed to enhance adoption into standard emergency care and improve patient outcomes.

High-Dose Buprenorphine Initiation in the Emergency Department Among Patients Using Fentanyl and Other Opioids.

This cohort study examines buprenorphine treatment initiation, response, and follow-up among patients presenting to California emergency departments (EDs) who reported fentanyl or other opioid use.

Incidence of Precipitated Withdrawal During a Multisite Emergency Department-Initiated Buprenorphine Clinical Trial in the Era of Fentanyl.

This cohort study examines the incidence of precipitated withdrawal comparing traditional sublingual buprenorphine with a 7-day extended-release injectable initiated in the emergency department (ED).

Prehospital Buprenorphine Treatment for Opioid Use Disorder by Paramedics: First Year Results of the EMS Buprenorphine Use Pilot.

BACKGROUND: Prehospital initiation of buprenorphine treatment for Opioid Use Disorder (OUD) by paramedics is an emerging potential intervention to reach patients at greatest risk for opioid-related death. Emergency medical services (EMS) patients who are at high risk for overdose deaths may never engage in treatment as they frequently refuse transport to the hospital after naloxone reversal. The potentially important role of EMS as the initiator for medication for opioid use disorder (MOUD) in the most high-risk patients has not been well described. SETTING: This project relies on four interventions: a public access naloxone distribution program, an electronic trigger and data sharing program, an "Overdose Receiving Center," and a paramedic-initiated buprenorphine treatment. For the final intervention, paramedics followed a protocol-based pilot that had an EMS physician consultation prior to administration. RESULTS: There were 36 patients enrolled in the trial study in the first year who received buprenorphine. Of those patients receiving buprenorphine, only one patient signed out against medical advice on scene. All other patients were transported to an emergency department and their clinical outcome and 7 and 30 day follow ups were determined by the substance use navigator (SUN). Thirty-six of 36 patients had follow up data obtained in the short term and none experienced any precipitated withdrawal or other adverse outcomes. Patients had a 50% (18/36) rate of treatment retention at 7 days and 36% (14/36) were in treatment at 30 days. CONCLUSION: In this small pilot project, paramedic-initiated buprenorphine in the setting of data sharing and linkage with treatment appears to be a safe intervention with a high rate of ongoing outpatient treatment for risk of fatal opioid overdoses.

48-hour Induction of Transdermal Buprenorphine to Sublingual Buprenorphine/Naloxone: The IPPAS Method.

Buprenorphine is an effective medication for the treatment of opioid use disorder. However, the traditional method of buprenorphine induction requires a period of abstinence and the development of at least moderate withdrawal, which can be barriers in starting treatment. We present the case of a hospitalized patient with opioid use disorder using unregulated fentanyl, who underwent a transdermal buprenorphine induction over 48 hours to initiate sublingual buprenorphine/naloxone on the third day. The patient experienced minimal levels of withdrawal and did not experience precipitated withdrawal. The ease of use of this novel induction method over previously published induction protocols can greatly improve the accessibility of buprenorphine for patients and healthcare staff.

Effectiveness of Substance Use Navigation for Emergency Department Patients With Substance Use Disorders: An Implementation Study.

STUDY OBJECTIVE: We implemented a whole person care-informed intervention delivered by substance use navigators (SUN) for emergency department (ED) patients with substance use disorders. METHODS: This was an implementation study of adult patients discharged from 3 public hospital EDs between September 1, 2021 through January 31, 2022 with cocaine, methamphetamine, alcohol, and opioid use-related diagnoses. The primary effectiveness outcome was treatment engagement within 30 days of ED discharge among patients with and without the SUN intervention. We used logistic regression and nearest neighbor propensity score matching without replacement to control for confounding effects. RESULTS: There were 1,328 patients in the cohort, and 119 (9.0%) received the SUN intervention; 50.4% of patients in the SUN intervention group and 15.9% of patients without the SUN intervention were engaged in outpatient treatment within 30 days of ED discharge (difference in proportions: 34.5%, 95% confidence interval [CI] 25.3% to 43.8%). In the unadjusted analysis, the SUN intervention was associated with higher rates of treatment engagement after ED discharge for patients with alcohol, opioid, and cocaine-related diagnoses; patients with methamphetamine-related diagnoses had low engagement rates with or without the SUN intervention. In addition, the SUN intervention was associated with higher odds of treatment engagement in the multivariable model (aOR 3.7, 95% CI 2.4 to 5.8) and in the propensity score-matched analysis (OR 2.1, 95% CI 1.2 to 3.5). CONCLUSION: A whole person care-informed intervention delivered by SUNs for ED patients with substance use disorders was strongly associated with higher engagement rates in addiction treatment after discharge.

A Neuropharmacological Model to Explain Buprenorphine Induction Challenges.

Buprenorphine induction for treating opioid use disorder is being implemented in emergency care. During this era of high-potency synthetic opioid use, novel and divergent algorithms for buprenorphine induction are emerging to optimize induction experience, facilitating continued treatment. Specifically, in patients with chronic fentanyl or other drug exposures, some clinicians are using alternative buprenorphine induction strategies, such as quickly maximizing buprenorphine agonist effects (eg, macrodosing) or, conversely, giving smaller initial doses and slowing the rate of buprenorphine dosing to avoid antagonist/withdrawal effects (eg, microdosing). However, there is a lack of foundational theory and empirical data to guide clinicians in evaluating such novel induction strategies. We present data from clinical studies of buprenorphine induction and propose a neuropharmacologic working model, which posits that acute clinical success of buprenorphine induction (achieving a positive agonist-to-withdrawal balance) is a nonlinear outcome of the opioid balance at the time of initial buprenorphine dose and mu-opioid-receptor affinity, lipophilicity, and mu-opioid-receptor intrinsic efficacy (the "ALE value") of the prior opioid. We discuss the rationale for administering smaller or larger doses of buprenorphine to optimize the patient induction experience during common clinical situations.

Buprenorphine for High-dose Tramadol Dependence: A Case Report of Successful Outpatient Treatment.

INTRODUCTION: During the coronavirus disease 2019 pandemic caused by the severe acute respiratory syndrome coronavirus 2, deaths from opiate drug overdoses reached their highest recorded annual levels in 2020. Medication-assisted treatment for opiate use disorder has demonstrated efficacy in reducing opiate overdoses and all-cause mortality and improving multiple other patient-centered outcomes. Treatment of tramadol dependence in particular poses unique challenges due to its combined action as opioid agonist and serotonin-norepinephrine reuptake inhibitor. Tramadol puts patients with dependence at risk for atypical withdrawal syndromes when attempting to reduce use. Little evidence is available to guide treatment of tramadol dependence. CASE REPORT: We present a case of high-dose tramadol addiction that began with misuse of medically prescribed tramadol for treatment of musculoskeletal back pain. The patient's use reached oral consumption of 5000-6000 milligrams of illicit tramadol daily. She complained of common complications of tramadol use disorder including memory impairment, excessive sedation, and tramadol-induced seizures. The patient was referred to the emergency department in a withdrawal crisis seeking treatment where she was successfully managed with buprenorphine and phenobarbital and then linked to ongoing outpatient treatment. CONCLUSION: Our report adds to the limited guidance currently available on the acute management of tramadol withdrawal and treatment of tramadol use disorder. Our case suggests the initiation of high-dose buprenorphine may be an effective and feasible option for emergency clinicians.

The Social Context of Unhealthy Alcohol Use Among Emergency Department Patients: A Cross Sectional Study.

BACKGROUND: Housing status and additional social determinants of health are important data for clinicians and policy makers to design and implement effective interventions for emergency department (ED) patients with unhealthy alcohol use (UAU). METHODS: We surveyed patients in an urban, safety-net ED from June to August 2018. UAU was assessed by a validated single-item screening question endorsed by the National Institute on Alcohol Abuse and Alcoholism. Housing status was assessed using items validated for housing stability. RESULTS: Seven hundred fifty-eight patients completed the survey (60% response rate), and 296 (39%; 95% confidence interval: 36%-43%) reported UAU. Patients with and without UAU had the same rates of ED visits (median 2, interquartile range: 1-4; P = 0.69) and hospitalizations (median 0, interquartile range: 0-0; P = 0.31) in the 12 months before index visit. Patients with UAU were more likely to lack stable housing compared to patients without UAU (69% vs 59%; P = 0.006). Illicit drug use and prescription drug misuse was more common in patients with UAU compared to those without UAU (29% vs 14%, P < 0.001; and 18% vs 10%; P < 0.001, respectively). Only 60 (20.3%) of the 296 patients with UAU had a documented diagnosis of UAU in the medical record. CONCLUSIONS: UAU is common in the general ED patient population and usually not clinically recognized. Patients with UAU have high rates of homelessness and co-occurring substance use. Future studies should consider strategies to incorporate social determinants of health and harm reduction treatments into ED-based interventions for UAU.

Prehospital Initiation of Buprenorphine Treatment for Opioid Use Disorder by Paramedics.

Prehospital initiation of buprenorphine treatment for Opioid Use Disorder (OUD) by paramedics is an emerging potential intervention. Many patients who may be at high risk for overdose deaths may never engage in treatment because they frequently refuse transport. Recent data have demonstrated a significant increase in both short and long term mortality following an opioid overdose. We describe 3 preliminary cases with a novel intervention of initiating Buprenorphine in the prehospital setting for symptoms of opioid withdrawal, regardless of etiology. In addition, we describe tracking of long term engagement in additional services as part of an integrated approach to combatting the opioid epidemic through EMS focused interventions.

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

BACKGROUND: Optimal treatment of buprenorphine precipitated opioid withdrawal (BPOW) is unclear. Full agonist treatment of BPOW is limited by buprenorphine's high-affinity blockade at mu-opioid receptors (µORs). Buprenorphine's partial agonism (low intrinsic efficacy) at µORs can limit the effectiveness of even massive doses once BPOW has begun. Adjunct medications, such as clonidine, are rarely effective in severe BPOW. Ketamine is an N -methyl-D-aspartate receptor antagonist with a potentially ideal pharmacologic profile for treatment of BPOW. Ketamine reduces opioid withdrawal symptoms independently of direct µOR binding, synergistically potentiates the effectiveness of buprenorphine µOR signaling, reverses (resensitizes) fentanyl induced µOR receptor desensitization, and inhibits descending pathways of hyperalgesia and central sensitization. Ketamine's rapid antidepressant effects potentially address depressive symptoms and subjective distress that often accompanies BPOW. Ketamine is inexpensive, safe, and available in emergency departments. To date, neither ketamine as treatment for BPOW nor to support uncomplicated buprenorphine induction has been described. CASE DESCRIPTION: We report a case of an illicit fentanyl-using OUD patient who experienced severe BPOW during an outpatient low-dose cross taper buprenorphine induction (ie, "microdose"). The BPOW was successfully treated in the emergency department with a combination of ketamine (0.6 mg/kg intravenous over 1 hour) combined with high-dose buprenorphine (16 mg sublingual single dose); 3 days later he was administered a month-long dose of extended-release subcutaneous buprenorphine which was repeated monthly (300 mg). At 90 days the patient remained in treatment and reported continuous abstinence from fentanyl use. CONCLUSIONS: This single case observation raises important questions about the potential therapeutic role of ketamine as a treatment for BPOW. BPOW is an important clinical problem for which there is currently only limited guidance and no universally accepted approach. Prospective study comparing the effectiveness of differing pharmacologic approaches to treat BPOW is urgently needed.