Operational definition of precipitated opioid withdrawal

Successful administration of extended-release buprenorphine in the emergency department

INTRODUCTION

The ongoing opioid epidemic in the United States has resulted in a substantial increase in overdose deaths and related morbidity and mortality. Given that emergency departments (ED) frequently serve as the initial point of contact for individuals experiencing opioid overdose or seeking treatment for opioid use disorder (OUD), ED clinicians have a pivotal role to play in providing prompt and effective treatment for OUD. While ED clinicians routinely administer sublingual and other transmucosal formulations of buprenorphine, extended-release buprenorphine (BUP-XR) remains underutilized in the ED.

CASE REPORT

We present a case involving the successful administration of BUP-XR in the ED to a patient experiencing spontaneous opioid withdrawal. The patient tolerated test dosing of sublingual buprenorphine (BUP-SL) and subsequently received BUP-XR in the ED. Following this intervention, the patient was referred to the hospital-affiliated substance use disorder outpatient clinic, where he has since demonstrated successful follow-up and retention in treatment.

CONCLUSION

Our report adds to the existing limited literature on the administration of BUP-XR in the ED and highlights the need for more comprehensive clinician teaching and guidance, as well as the establishment of in-hospital protocols for BUP-XR. Despite these challenges, our case indicates that initiating BUP-XR could be a viable and effective option for ED patients with OUD.

Incidence of buprenorphine-precipitated opioid withdrawal in adults with opioid use disorder: A systematic review

BACKGROUND AND AIMS

Buprenorphine is an evidence-based treatment for opioid use disorder, and the risk of precipitated withdrawal contributes to its underuse. The goal of this systematic review was to determine the incidence of buprenorphine-precipitated withdrawal in adults with opioid use disorder.

METHODS

This systematic review was registered on PROSPERO (CRD42023437634). We searched Medline, Embase Classic + Embase, and Cochrane CENTRAL from inception to 10 November 2023, and included original research that reported the incidence of sublingual buprenorphine-precipitated withdrawal in adults with opioid use disorder. Primary screening was completed by four independent reviewers. Full text review, data extraction and risk of bias assessments using the Newcastle Ottawa Scale and the Cochrane Risk of Bias 2 tool were completed by two independent reviewers. The primary outcome was precipitated withdrawal. Secondary outcomes were baseline opioids used, induction dose, initial Clinical Opiate Withdrawal Scale (COWS) score, location of induction, definition and severity of precipitated withdrawal and adverse events. The range of incidence of precipitated withdrawal across studies was described.

RESULTS

Our search yielded 10 197 unique citations. Twenty-one cohort and five randomized trials met inclusion criteria (n = 4497, range 20-1293). The overall incidence of precipitated withdrawal ranged from 0 to 13.2%. Nine studies defined precipitated withdrawal; definitions were inconsistent. Most patients used heroin at baseline. The most common initial dose of buprenorphine was between 2 mg and 8 mg (range: 0.075 mg-24 mg). Initial minimum COWS score ranged from 5 to 13. Induction locations included home, inpatient, emergency department, pre-hospital, outpatient and residential units. Of the fifteen studies with cases of precipitated withdrawal, nine studies did not report the severity of withdrawal experienced. Other induction-related adverse events varied. The overall quality of included studies was poor.

CONCLUSIONS

The best available evidence suggests the incidence of buprenorphine-precipitated withdrawal in adults with opioid use disorder is low and should not be a barrier to use.

Buprenorphine-Precipitated Withdrawal Among Hospitalized Patients Using Fentanyl

Importance

Buprenorphine treatment of opioid use disorder (OUD) is safe and effective, but opioid withdrawal during treatment initiation is associated with poor retention in care. As fentanyl has replaced heroin in the drug supply, case reports and surveys have indicated increased concern for buprenorphine-precipitated withdrawal (PW); however, some observational studies have found a low incidence of PW.

Objective

To estimate buprenorphine PW incidence and assess factors associated with PW among emergency department (ED) or hospitalized patients.

Design, Setting, and Participants

This retrospective cohort study at 3 academic hospitals in Philadelphia, Pennsylvania, included adults with OUD who underwent traditional or high-dose buprenorphine initiation between January 1, 2020, and December 31, 2021. Exclusion criteria included low-dose buprenorphine initiation and missing documentation of opioid withdrawal severity within 4 hours of receiving buprenorphine.

Exposure

Buprenorphine initiation with an initial dose of at least 2 mg of sublingual buprenorphine after a Clinical Opiate Withdrawal Scale (COWS) score of 8 or higher. Additional exposures included 4 predefined factors potentially associated with PW: severity of opioid withdrawal before buprenorphine (COWS score of 8-12 vs ≥13), initial buprenorphine dose (2 vs 4 or ≥8 mg), body mass index (BMI) (<25 vs 25 to <30 or ≥30; calculated as weight in kilograms divided by height in meters squared), and urine fentanyl concentration (0 to <20 vs 20 to <200 or ≥200 ng/mL).

Main Outcome and Measures

The main outcome was PW incidence, defined as a 5-point or greater increase in COWS score from immediately before to within 4 hours after buprenorphine initiation. Logistic regression was used to estimate the odds of PW associated with the 4 aforementioned predefined factors.

Results

The cohort included 226 patients (150 [66.4%] male; mean [SD] age, 38.6 [10.8] years). Overall, 26 patients (11.5%) met criteria for PW. Among patients with PW, median change in COWS score was 9 points (IQR, 6-13 points). Of 123 patients with confirmed fentanyl use, 20 (16.3%) had PW. In unadjusted and adjusted models, BMI of 30 or greater compared with less than 25 (adjusted odds ratio [AOR], 5.12; 95% CI, 1.31-19.92) and urine fentanyl concentration of 200 ng/mL or greater compared with less than 20 ng/mL (AOR, 8.37; 95% CI, 1.60-43.89) were associated with PW.

Conclusions and Relevance

In this retrospective cohort study, 11.5% of patients developed PW after buprenorphine initiation in ED or hospital settings. Future studies should confirm the rate of PW and assess whether bioaccumulated fentanyl is a risk factor for PW.

Endogenous opiates and behavior: 2023

This paper is the forty-sixth consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2023 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug and alcohol abuse (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

Establishing a research agenda for the study and assessment of opioid withdrawal

The opioid crisis is an international public health concern. Treatments for opioid use disorder centre largely on the management of opioid withdrawal, an aversive collection of signs and symptoms that contribute to opioid use disorder. Whereas in the past 50 years more than 90 medications have been developed for depression, only five medications have been developed for opioid use disorder during this period. We posit that underinvestment has occurred in part due to an underdeveloped understanding of opioid withdrawal syndrome. This Personal View summarises substantial gaps in our understanding of opioid withdrawal that are likely to continue to limit major advancements in its treatment. There is no firm consensus in the field as to how withdrawal should be precisely defined; 10-550 symptoms of withdrawal can be measured on 18 scales. The imprecise understanding of withdrawal is likely to result in overestimating or underestimating the severity of an individual's withdrawal syndrome or potential therapeutic effects of different candidate medications. The severity of the opioid crisis is not remitting, and an international research agenda for the study and assessment of opioid withdrawal is necessary to support transformational changes in withdrawal management and treatment of opioid use disorder. Nine actionable targets are delineated here: develop a consensus definition of opioid withdrawal; understand withdrawal symptomatology after exposure to different opioids (particularly fentanyl); understand precipitated opioid withdrawal; understand how co-exposure of other drugs (eg, xylazine and stimulants) influences withdrawal expression; examine individual variation in withdrawal phenotypes; precisely characterise the protracted withdrawal syndrome; identify biomarkers of opioid withdrawal severity; identify predictors of opioid withdrawal severity; and understand which symptoms are most closely associated with treatment attrition or relapse. The US Food and Drug Administration recently established a formal indication for opioid withdrawal that has invigorated interest in drug development for opioid withdrawal management. Action is now needed to support these interests and help industry identify new classes of medications so that real change can be achieved for people with opioid use disorder.

Withdrawal during outpatient low dose buprenorphine initiation in people who use fentanyl: a retrospective cohort study

BACKGROUND

Buprenorphine is an effective treatment for opioid use disorder (OUD); however, buprenorphine initiation can be complicated by withdrawal symptoms including precipitated withdrawal. There has been increasing interest in using low dose initiation (LDI) strategies to reduce this withdrawal risk. As there are limited data on withdrawal symptoms during LDI, we characterize withdrawal symptoms in people with daily fentanyl use who underwent initiation using these strategies as outpatients.

METHODS

We conducted a retrospective chart review of patients with OUD using daily fentanyl who were prescribed 7-day or 4-day LDI at 2 substance use disorder treatment clinics in San Francisco. Two addiction medicine experts assessed extracted chart documentation for withdrawal severity and precipitated withdrawal, defined as acute worsening of withdrawal symptoms immediately after taking buprenorphine. A third expert adjudicated disagreements. Data were analyzed using descriptive statistics.

RESULTS

There were 175 initiations in 126 patients. The mean age was 37 (SD 10 years). 71% were men, 26% women, and 2% non-binary. 21% identified as Black, 16% Latine, and 52% white. 60% were unstably housed and 75% had Medicaid insurance. Substance co-use included 74% who used amphetamines, 29% cocaine, 22% benzodiazepines, and 19% alcohol. Follow up was available for 118 (67%) initiations. There was deviation from protocol instructions in 22% of these initiations with follow up. 31% had any withdrawal, including 21% with mild symptoms, 8% moderate and 2% severe. Precipitated withdrawal occurred in 10 cases, or 8% of initiations with follow up. Of these, 7 had deviation from protocol instructions; thus, there were 3 cases with follow up (3%) in which precipitated withdrawal occurred without protocol deviation.

CONCLUSIONS

Withdrawal was relatively common in our cohort but was mostly mild, and precipitated withdrawal was rare. Deviation from instructions, structural barriers, and varying fentanyl use characteristics may contribute to withdrawal. Clinicians should counsel patients who use fentanyl that mild withdrawal symptoms are likely during LDI, and there is still a low risk for precipitated withdrawal. Future studies should compare withdrawal across initiation types, seek ways to support patients in initiating buprenorphine, and qualitatively elicit patients' withdrawal experiences.

Different projection neurons of basolateral amygdala participate in the retrieval of morphine withdrawal memory with diverse molecular pathways

Context-induced retrieval of drug withdrawal memory is one of the important reasons for drug relapses. Previous studies have shown that different projection neurons in different brain regions or in the same brain region such as the basolateral amygdala (BLA) participate in context-induced retrieval of drug withdrawal memory. However, whether these different projection neurons participate in the retrieval of drug withdrawal memory with same or different molecular pathways remains a topic for research. The present results showed that (1) BLA neurons projecting to the prelimbic cortex (BLA-PrL) and BLA neurons projecting to the nucleus accumbens (BLA-NAc) participated in context-induced retrieval of morphine withdrawal memory; (2) there was an increase in the expression of Arc and pERK in BLA-NAc neurons, but not in BLA-PrL neurons during context-induced retrieval of morphine withdrawal memory; (3) pERK was the upstream molecule of Arc, whereas D1 receptor was the upstream molecule of pERK in BLA-NAc neurons during context-induced retrieval of morphine withdrawal memory; (4) D1 receptors also strengthened AMPA receptors, but not NMDA receptors, -mediated glutamatergic input to BLA-NAc neurons via pERK during context-induced retrieval of morphine withdrawal memory. These results suggest that different projection neurons of the BLA participate in the retrieval of morphine withdrawal memory with diverse molecular pathways.

Evaluation of Low-dose Buprenorphine Initiation With Buprenorphine Buccal Films in Hospitalized Patients: A Retrospective Cohort Study

OBJECTIVE

Low-dose buprenorphine initiation (LDBI) strategies to transition patients from full opioid agonists to buprenorphine have previously been described using sublingual films, intravenous solution, transdermal patches, and, more recently, buccal films. The objective of this study was to describe the effectiveness of LDBI using novel titration schedules with buccal films.

METHODS

This is a retrospective cohort study of hospitalized patients with opioid use disorder (OUD) or physiologic dependence to opioids who underwent LDBI with buprenorphine buccal films at NYU Langone Health. Two LDBI protocols were evaluated, including a short titration schedule over 4 days and a long schedule over 7 days. The primary outcomes of interest included LDBI completion rates and incidence of opioid withdrawal.

RESULTS

Forty-two patients underwent 46 LDBIs at NYU Langone Health between October 2020 and April 2022. The cohort comprised patients with OUD (57%), chronic pain with OUD (33%), and chronic pain without OUD (10%). Indications for LDBI most commonly included co-occurring pain precluding discontinuation of full opioid agonists (72%), prior history of precipitated withdrawal (30%), and methadone use (23%). The overall completion rate of LDBI was 78%. Withdrawal was encountered in 33% of patients; however, only 2 patients required LDBI discontinuation as a result. On multivariate analysis, a diagnosis of OUD was independently associated with withdrawal during LDBI.

CONCLUSIONS

Buprenorphine buccal films can successfully be used off-label to facilitate LDBI in the hospital setting. We present 4- and 7-day titration protocols, which were well-tolerated, and provide practical considerations for use.

Listening to the Data: Computational Approaches to Addiction and Learning

Computational approaches hold great promise for identifying novel treatment targets and creating translational therapeutics for substance use disorders. From circuitries underlying decision-making to computationally derived neural markers of drug-cue reactivity, this review is a summary of the approaches to data presented at our 2023 Society for Neuroscience Mini-Symposium. Here, we highlight data- and hypothesis-driven computational approaches that recently afforded advancements in addiction and learning neuroscience. First, we discuss the value of hypothesis-driven algorithmic modeling approaches, which integrate behavioral, neural, and cognitive outputs to refine hypothesis testing. Then, we review the advantages of data-driven dimensionality reduction and machine learning methods for uncovering novel predictor variables and elucidating relationships in high-dimensional data. Overall, this review highlights recent breakthroughs in cognitive mapping, model-based analysis of behavior/risky decision-making, patterns of drug taking, relapse, and neuromarker discovery, and showcases the benefits of novel modeling techniques, across both preclinical and clinical data.