A Narrative Pharmacological Review of Buprenorphine: A Unique Opioid for the Treatment of Chronic Pain

Retrospective Observational Descriptive Study on Use and Rotations to Belbuca®

The purpose of this study was to better characterize morphine equivalent daily dose (MEDD) equivalencies with buccal buprenorphine, and identify real-world efficacy and safety outcomes associated with the use of buccal buprenorphine for chronic pain at a local VA Medical Center. This study was a retrospective chart review of Computerized Patient Record System (CPRS) patient records with outpatient prescriptions for buccal buprenorphine (Belbuca®). Overall, there was a high discontinuation rate of Belbuca®: being 60% or greater across all different patient groups. These high attrition rates may potentially be result of failure to titrate to an optimal dose of Belbuca® needed for adequate analgesia. Those fully rotated fared marginally better than those partially rotated in that those fully rotated discontinued at a lesser rate and less quickly than those who were partially rotated. From the results of this study, a local dosing scheme for Belbuca® based on baseline MEDD was created for facility level guidance. The exact MEDD conversion ratio, however, for individual buprenorphine products as well as MEDD contributed by these products on a patient's overall opioid related risk compared to other full agonist opioids still remains unclear and further studies are warranted.

Structural Determinants of Buprenorphine Partial Agonism at the μ-Opioid Receptor

The μ-opioid receptor (μOR) is a class A G Protein-Coupled Receptor (GPCR) targeted by natural and synthetic ligands to provide analgesia to patients with pain of various etiologies. Available opioid medications present several unwanted side effects, stressing the need for safer pain therapies. Despite the attractive proposal that biasing μOR signaling toward G protein pathways would lead to fewer side effects, recent studies indicate that low-efficacy opioid drugs, such as buprenorphine, may represent a safer alternative. In the present work, we combine molecular docking, microsecond-time scale molecular dynamics (MD) simulations, and metadynamics to investigate the conformational dynamics of the μOR bound to morphine or buprenorphine. Our objective was to determine structural aspects associated with the unique pharmacological effects caused by the latter, taking morphine as a reference. MD simulations identified a salt bridge with D1493.32 as crucial for stabilizing both ligands into the μOR orthosteric site, with this interaction being weaker in buprenorphine. The morphinan-scaffold of both ligands shared contacts with transmembrane (TM) helix residues of the receptor, including TM3, TM5, TM6, and TM7. Conversely, while morphine showed stronger interactions with a few TM3 residues, additional chemical groups of buprenorphine showed stronger interactions with TM2, extracellular loop 2 (ECL2), and TM7 residues. We also observed distinct TM arrangements induced by these ligands, with buprenorphine causing an extracellular outward movement of TM7 and morphine provoking intracellular inward movements of TM5 and TM7 of the receptor. In addition, we found that buprenorphine tends to explore deeper regions in the μOR orthosteric site, further supported by funnel-metadynamics, resulting in diverse side chain orientations of W2956.48. Metadynamics also unveiled distinct intermediate states for morphine and buprenorphine, with the latter accessing a secondary binding site associated with partial μOR agonists. Our results indicate that the weakened salt bridge of buprenorphine with D1493.32, along with the strong TM7 interaction through its cyclopropyl group, may explain its low efficacy and consequent partial μOR agonism. Furthermore, ECL2 interactions may contribute to explaining the biased agonism of buprenorphine, a common feature shared with other opioid modulators with similar functional effects. Our study sheds light on the complex pharmacology of buprenorphine, identifying structural aspects associated with its partial and biased μOR agonism. These results can provide valuable information for the design of new effective and safer opioid drugs.

Treatment Experience Using a Micro-Induction Buprenorphine Protocol for Chronic Pain in Pediatric Sickle Cell Disease

BACKGROUND

Patients with sickle cell disease (SCD) experience painful vaso-occlusive episodes that increase with age; a subset develops chronic pain (CP). CP is usually managed with acute pain management guidelines despite evidence of ineffectiveness. Buprenorphine (BUP), a partial opioid agonist, is a potent analgesic with less euphoric effect and a respiratory "ceiling effect." BUP therefore provides an alternative "harm reduction" approach for CP management in pediatric SCD patients.

METHODS

This single urban center retrospective study assessed the feasibility of inpatient transition to BUP-containing analgesics in adolescents with SCD and CP. Patients aged 12-20 years who transitioned from full opioid agonists (FOA) to BUP between December 2020 and September 2022 were included. Acute care utilization, hospital length of stay, and FOA use in both inpatient and outpatient settings were compared pre- and post-BUP induction for up to a year.

RESULTS

Fourteen adolescents with SCD underwent inpatient BUP induction and maintenance therapy. Inpatient transition using a micro-induction approach was feasible and well tolerated in this population. There were low rates of adverse events, such as opioid withdrawal signs. Maintenance on BUP products was sustainable over the 1-year post-induction period. Three patients (21%) discontinued BUP during maintenance therapy. There was a significant reduction (p < 0.05) in acute care utilization, length of stay, and FOA use (both inpatient and outpatient).

CONCLUSION

Inpatient micro-induction to BUP from FOA in adolescent SCD patients with CP is feasible with minimal signs of opioid withdrawal. This study suggests decreased acute care utilization with BUP.

Cancer-Related Pain Management in Pregnancy-A Review

Background: Cancer-related pain management in pregnant patients is a complex clinical challenge requiring a careful balance between effective maternal analgesia and fetal safety. The pathophysiology of cancer-related pain varies, necessitating a nuanced, individualized approach to treatment with careful consideration of maternal-fetal safety, and pharmacokinetics. Objectives: This review aims to explore safe and effective pharmacological and interventional strategies for managing cancer-related pain in pregnant patients while highlighting disparities in access to care. Design: A comprehensive literature review was conducted. A total of 4766 articles were identified, with 98 studies included for final analysis after exclusion. Setting/Subjects: Studies included pregnant individuals with various hematological and solid tumor malignancies across various community and academic settings. Measurements: Pain typology was categorized (nociceptive or neuropathic), with treatment options including commonly available over-the-counter medications, opioids, various neuropathic medications, and interventional pain management options. In addition to pharmacological efficacy and maternofetal safety profiles, interventional efficacy, and socio-cultural influences on care were also measured. Disparities in access to care were also analyzed. Results: Analgesic options in pregnancy include acetaminophen, opioids, certain neuropathic medications, with very cautious use of NSAIDs. Interventional methods-neuraxial anesthesia, nerve blocks, spinal cord stimulation-offer adjunctive benefit if done under ultrasound guidance, but fluoroscopy and radiation guided modalities are best avoided in pregnancy. Diverse populations often encountered significant barriers to adequate pain control. Conclusions: Optimal cancer pain management in pregnancy necessitates a multidisciplinary, and individually tailored approach. Enhancing clinical evidence, and ensuring culturally competent care are critical to improving outcomes in this patient population.

Embryonic Zebrafish Irritant-evoked Hyperlocomotion (EZIH) as a high-throughput behavioral model for nociception

Behavioral models have served a key role in understanding nociception, the sensory system by which animals detect noxious stimuli in their environment. Developing zebrafish (Danio rerio) are a powerful study organism for examining nociceptive pathways, given the vast array of genetic, developmental, and neuroscience tools available for these animals. However, at present there are few widely-adopted behavioral models for nociception in developing zebrafish. This study examines the locomotor response of hatching-stage zebrafish embryos to dilute solutions of the noxious chemical and TRPA1 agonist allyl isothiocyanate (AITC). At this developmental stage, AITC exposure induces a robust uniphasic hyperlocomotion response. This behavior was thoroughly characterized by determining the effects of pre-treatment with an array of pharmacological agents, including anesthetics, TRPA1 agonists/antagonists, opioids, NSAIDs, benzodiazepines, SSRIs, and SNRIs. Anesthetics suppressed the response to AITC, pre-treatment with TRPA1 agonists induced hyperlocomotion and blunted the response to subsequent AITC exposures, and TRPA1 antagonists and the opioid buprenorphine tended to reduce the response to AITC. The behavioral responses of zebrafish embryos to a noxious chemical were minimally affected by the other pharmacological agents examined. The feasibility of using this behavioral model as a screening platform for drug discovery efforts was then evaluated by assaying a library of natural product mixtures from microbial extracts and fractions. Overall, our results indicate that irritant-evoked locomotion in embryonic zebrafish is a robust behavioral model for nociception with substantial potential for examining the molecular and cellular pathways associated with nociception and for drug discovery efforts.

Strategy for effective analgesia with intravenous buprenorphine in patients with acute postoperative pain

BACKGROUND

Analgesic treatment is the primary method for managing acute postoperative pain. Opioid analgesics are the main class of drugs used to treat moderate to severe pain, whether it is acute or chronic. These opioids differ in various ways, including their pharmacochemical properties, distribution and absorption rates, metabolism, and elimination pathways for the drug and its metabolites. These differences result in varying degrees of analgesic efficacy, which, in clinical practice, allows for the selection of the most effective drug that maximizes pain relief while ensuring safety. Buprenorphine is a semi-synthetic opioid with properties that are not yet fully understood. It has a wide range of applications in treating both acute and chronic pain, including non-cancer and cancer-related pain. One of the most significant clinical advantages of buprenorphine is its safety profile, which includes a ceiling effect on respiratory depression, no immunosuppressive effects, inhibition of hyperalgesia, no cumulative effects in patients with renal failure, and a low risk of constipation following its use.

AIM

This study aims to analyze current reports on the use of intravenous buprenorphine as a first-line opioid analgesic for postoperative pain relief. The paper discusses the pharmacochemical properties of the drug and the mechanisms behind postoperative pain. Additionally, it presents the experiences of the pain management team at Copernicus Hospital in Gdansk regarding administering intravenous buprenorphine.

MATERIAL AND METHODS

The current literature on buprenorphine for treating moderate to severe acute pain has been reviewed, focusing on its effectiveness in managing postoperative pain following surgical procedures. Additionally, the experience of the Copernicus Hospital pain team with buprenorphine is summarized in a brief discussion.

CONCLUSION

After reviewing current literature and recommendations, along with the experiences of the pain management team at Copernicus Hospital in Gdańsk, it can be concluded that buprenorphine is an analgesic that demonstrates a high level of efficacy and safety. When used in combination with non-opioid analgesics, buprenorphine achieves a synergistic effect, resulting in effective pain relief. This approach facilitates early patient rehabilitation and enables a swift return to normal activities, even following extensive surgical procedures.

Trends in Outpatient Buprenorphine Prescribing for Chronic Pain: A Retrospective Analysis Over 18 Months

Background

Buprenorphine, a partial opioid agonist, has gained attention for its use in chronic pain management due to its lower risk of abuse and respiratory depression compared to traditional opioids. The utilization of buprenorphine for chronic pain has increased in recent years. This study aimed to analyze trends in buprenorphine prescribing for chronic pain in an outpatient setting over an 18-month period, excluding buprenorphine-naloxone combinations used for opioid use disorder and opioid dependence.

Methods

A retrospective chart review was conducted, examining outpatient buprenorphine and long-acting opioid prescriptions issued by three pain management physicians between January 1, 2023, and June 30, 2024. Prescription data were collected from electronic medical records (EMRs) and analyzed across three six-month intervals: January 1, 2023, to June 30, 2023; July 1, 2023, to December 31, 2023; and January 1, 2024, to June 30, 2024. Only unique buprenorphine prescriptions for chronic pain management were included, while buprenorphine-naloxone prescriptions for opioid use disorder were excluded. Long-acting opioids analyzed included extended release (ER) formulations including tramadol ER, morphine ER, hydrocodone ER, oxycodone ER, fentanyl, and methadone.

Results

Over the 18-month study period, a total of 61 unique buprenorphine prescriptions for chronic pain were issued by the three physicians. The number of prescriptions increased across each six-month period: 18 prescriptions were issued between January 1, 2023, and June 30, 2023; 20 prescriptions from July 1, 2023, to December 31, 2023; and 23 prescriptions from January 1, 2024, to June 30, 2024. This represents a 27.8% increase over the entire 18-month period. During the same timeframe, 117 long-acting opioid prescriptions (excluding buprenorphine) were issued in the first six-month period, 121 prescriptions in the second period, and 108 prescriptions in the third period. Buprenorphine prescriptions accounted for 13.3% of all long-acting opioid prescriptions in the first period (18 out of 135 total prescriptions), 14.2% in the second period (20 out of 141 total prescriptions), and 17.6% in the third period (23 out of 131 total prescriptions). Notably, while the absolute number of buprenorphine prescriptions increased steadily, its proportion relative to total long-acting opioid prescriptions also grew over time.

Conclusions

The findings demonstrate a steady increase in buprenorphine prescribing for chronic pain in the outpatient setting, while long-acting opioid prescriptions exhibited a slight decline in the later periods. The proportion of buprenorphine prescriptions relative to long-acting opioids increased over time, suggesting growing acceptance of buprenorphine as a safer alternative for chronic pain management. Further research is needed to explore the factors driving these prescribing patterns and the long-term clinical outcomes associated with buprenorphine use in chronic pain management.

Buprenorphine: an old dog with new tricks

PURPOSE OF REVIEW

The survival rate of patients with a cancer or palliative care diagnosis has improved over the years although pain remains a debilitating symptom that many patients still require treatment with opioids. Compared to full mu-opioid receptor agonists such as morphine and oxycodone, buprenorphine continues to remain a second- or third-line choice in this group of patients.We have reviewed the pharmacology and clinical utility of buprenorphine to stimulate debate around the first-line use of buprenorphine in the management of pain in cancer patients.

RECENT FINDINGS

Buprenorphine has a pharmacological profile that is unique and unlike any other opioid. It is associated with many immediate and long-term benefits, with lower risks of adverse effects that make it an ideal first-line choice in the management of cancer pain.

SUMMARY

Buprenorphine appears to be a promising choice of opioid for cancer patients. Studies have found that buprenorphine is a safe and effective choice for many patients, making it a suitable first-line option for the management of cancer pain.

Opioid use and abuse in adolescents and young adults; dealing with science, laws and ethics: Charming the COBRAS

The subject of substance use disorders in the pediatric population remains a disturbing conundrum for clinicians, researchers and society in general. Many of our youth are at risk of being damaged and even killed by drug addictions that result from the collision of rapidly developing as well as vulnerable central nervous systems encountering the current global drug addiction crisis. A major motif of this chemical calamity is opioid use disorder in adolescents and young adults that was stimulated by the 19th century identification of such highly addictive drugs as morphine, heroin and a non-opiate, cocaine. This analysis focuses on the pervasive presence of opioid drugs such as heroin and fentanyl that has become a major tragedy in the 21st century arising from an overall substance use and misuse phenomenon rampant in global society. Themes covered in this article include the history of addictive drugs in humans, diagnostic terms in use, the role of neurobiology in drug addiction, and current psychopharmacologic approaches to opioid overdose as well as addiction. Our youth are continuously confronted by dangers of high-risk behaviors including death and injury from opioid use disorders due to their central nervous system neuroplasticity as well as the widespread availability of these harmful chemicals. Healthcare professionals should actively assist our youth who unknowingly and even innocently encounter this deadly menace in the 21st century.

Peripartum buprenorphine and oxycodone exposure impair maternal behavior and increase neuroinflammation in new mother rats

7 % of pregnant people use opioids. Opioid use during pregnancy can negatively impact maternal and offspring health. Medications for opioid use disorder (MOUD), commonly buprenorphine, are the recommended treatment for opioid use disorder during pregnancy to prevent cycles of withdrawal and relapse. In addition to effects on opioid receptors, opioids have strong binding affinity to toll-like receptor (TLR) 4, an immune cell receptor, and thereby impact neuroinflammatory signaling. We have previously shown that neuroimmune alterations are important for the display of maternal behavior. Here, we used a rodent model to assess the impact of chronic peripartum opioid exposure or MOUD on maternal caregiving and neuroinflammation in the postpartum brain. Female rats were exposed to vehicle (VEH), buprenorphine (BUP) to model MOUD, or oxycodone (OXY), to model peripartum drug use, before, during, and after pregnancy. Opioid exposure reduced gestation length and maternal weight gain. Postpartum maternal caretaking behaviors, including pup retrieval, huddling and nursing, and pup-directed sniffing and licking, were reduced in opioid-exposed mothers. Following behavioral testing, tissue was collected from brain regions important for maternal caretaking, including the prefrontal cortex (PFC), nucleus accumbens (NAc), preoptic area (POA), amygdala (AMY), and periaqueductal grey (PAG). Immunofluorescent labeling showed that BUP increased astrocyte labeling, while OXY increased microglia labeling in the PAG, but not other regions. Gene expression analysis also showed regional and treatment differences in immune transcripts. BUP and OXY increased TLR4 in the PFC. BUP increased TNF in the NAc but decreased IL1β in the POA. OXY increased CD68 in the POA, and IL1β, TNF, and TLR4 in the PAG. Together, these results provide novel evidence of peripartum neuroimmune alterations following chronic opioid exposure that could be mediating maternal care deficits. This work provides a foundation to explore the extent to which modulation of neuroimmune activation may be a potential intervention for caregiving deficits in mothers exposed to opioids during pregnancy.

Low-Dose Buprenorphine Initiation for Hospitalized Patients With Chronic Pain and Opioid Use Disorder or Opioid Misuse: Protocol for an Open-Label, Parallel-Group, Effectiveness-Implementation Randomized Controlled Trial

Buprenorphine is an effective medication for both opioid use disorder (OUD) and chronic pain (CP), but transitioning from full opioid agonists to buprenorphine, a partial opioid agonist, can be challenging. Preliminary studies suggest that low-dose buprenorphine initiation can overcome some challenges in starting treatment, but no randomized controlled trials have compared low-dose and standard buprenorphine initiation approaches regarding effectiveness and safety or examined implementation in hospital settings. In a pragmatic open-label hybrid type I effectiveness-implementation trial based in a single urban health system, 270 hospitalized patients with (a) CP and (b) OUD or opioid misuse are being randomized to buprenorphine treatment initiation using 5-day low-dose or standard initiation protocols. Outcomes include buprenorphine treatment uptake (primary), defined as receiving buprenorphine treatment 7 days after enrollment, and other OUD and pain outcomes at 1-, 3-, and 6-month follow-up (secondary). Data collection will also include safety measures, implementation of low-dose initiation protocols, patient acceptability, and cost-effectiveness. Comparing strategies in a randomized clinical trial will provide the most definitive data to date regarding the effectiveness and safety of low-dose buprenorphine initiation. The study will also provide important data on treating CP at a time that clinical guidelines are evolving to center buprenorphine as a preferred opioid for CP.

Optimizing Safe Opioid Prescribing: A Paradigm Shift in Buprenorphine Management for Orthopaedic Surgery

The worsening opioid epidemic in the United States, exacerbated by the COVID-19 pandemic, necessitates innovative approaches to pain management. Buprenorphine, a long-acting opioid, has gained popularity due to its safety profile and accessibility. Orthopaedic surgeons, encountering an increasing number of patients on buprenorphine, face challenges in perioperative management. This article will update orthopaedic surgeons on new developments in the understanding of buprenorphine as a pain reliever and share evidence-based practice guidelines for buprenorphine management. For patients on buprenorphine for opioid use disorder or chronic pain, the updated recommendation is to continue their home dose of buprenorphine through the perioperative period. The patient's buprenorphine prescriber should be contacted and notified of any impending surgery. The continuation of buprenorphine should be accompanied by a multimodal approach to analgesia, including a preoperative discussion about expectations of pain and pain control, regional anesthesia, standing acetaminophen, Nonsteroidal anti-inflammatory drugs when possible, gabapentinoids at night for patients under 65 years, cryotherapy, elevation, and early mobilization. Patients can also be prescribed short-acting, immediate-release opioids for breakthrough pain. Transdermal buprenorphine is emerging as an excellent option for the management of acute perioperative pain in both elective and nonelective orthopaedic patients. A single patch can provide a steady dose of pain medication for up to 1 week during the postoperative period. A patch delivery method can help combat patient nonadherence and ultimately provide better overall pain control. In the future, transdermal buprenorphine patches could be applied in virtually all fracture surgery, spinal surgery, total joint arthroplasty, ligament reconstructions with bony drilling, etc. As the stigma surrounding buprenorphine decreases, further opportunities for perioperative use may develop.

Pharmacological Pain Treatment in Older Persons

Pharmacological pain treatment in older persons is presented by a multi-disciplinary group of European pain experts. Drugs recommended for acute or chronic nociceptive pain, also for neuropathic pain and the routes of administration of choice are the same as those prescribed for younger persons but comorbidities and polypharmacy in older persons increase the risk of adverse effects and drug interactions. Not all drugs are available or authorised in all European countries. For mild-to-moderate pain, non-opioids including paracetamol and non-steroidal anti-inflammatory drugs are first-line treatments, followed by nefopam and metamizole. Codeine, dihydrocodeine and tramadol are prescribed for moderate to severe pain and 'strong' opioids, including morphine, hydromorphone, oxycodone, fentanyl, buprenorphine, methadone and tapentadol, for severe pain. Chronic neuropathic pain treatment relies on coanalgesics, including anti-epileptics (gabapentinoids) and anti-depressants with additional option of topical lidocaine and capsaicine. The choice of analgesic(s) and the route of administration should be guided by the pain characteristics, as well as by the patient's comorbidities, organ function and medications. Several directions have been highlighted to optimise pharmacological pain management in older individuals: (1) before starting pain treatment adequately detect and assess pain and always perform a full geriatric assessment, (2) consider kidney function systematically to adjust the doses of analgesics and avoid the risks of overdose, (3) start with the lowest dose of an analgesic and increase it gradually under the control of the effect, (4) involve the older persons and family in their treatment, (5) reevaluate pain regularly during treatment and (6) combine pharmacological treatment with non-pharmacological approaches.

Opioid metabolism and drug-drug interaction in cancer

Concomitant use of multiple drugs in most patients with cancer may result in drug-drug interactions (DDIs), potentially causing serious adverse effects. These patients often experience unrelieved cancer-related pain (CRP) during and after cancer treatment, which can lead to a reduced quality of life. Opioids can be used as part of a multimodal pain management strategy when non-opioid analgesics are not providing adequate pain relief, not tolerated, or are contraindicated. However, due to their narrow therapeutic window, opioids are more susceptible to adverse events when a DDI occurs. Clinically relevant DDIs with opioids are usually pharmacokinetic, mainly occurring via metabolism by cytochrome P450 (CYP). This article aims to provide an overview of potential DDIs with opioids often used in the treatment of moderate-to-severe CRP and commonly used anticancer drugs such as chemotherapeutics, tyrosine kinase inhibitors (TKIs), or biologics. A DDI-checker tool was used to contextualize the tool-informed DDI assessment outcomes with clinical implications and practice. The findings were compared to observations from a literature search conducted in Embase and PubMed to identify clinical evidence for these potential DDIs. The limited results mainly included case studies and retrospective reviews. Some potential DDIs on the DDI-checker were aligned with literature findings, while others were contradictory. In conclusion, while DDI-checkers are useful tools in identifying potential DDIs, it is necessary to incorporate literature verification and comprehensive clinical assessment of the patient before implementing tool-informed decisions in clinical practice.

Opioid system and related ligands: from the past to future perspectives

Chronic pain is a pathological condition affecting about 30% of population. It represents a relevant social-health issue worldwide, and it is considered a significant source of human suffering and disability, strongly affecting patients' quality of life. Despite several pharmacological strategies to guarantee an adequate pain management have been proposed over the years, opioids still represent one of the primary choices for treating moderate-to-severe pain in both cancer and non-cancer patients. However, chronic use of opioids often leads to numerous side effects, including respiratory depression, constipation, analgesic tolerance, and opioid-induced hyperalgesia (OIH), which can strongly limit their use. Given the fundamental role of opioid system in pain relief, this review provides a general overview about the main actors (endogenous opioid peptides and receptors) involved in its modulation. Furthermore, this review explores the action and the limitations of conventional clinically used opioids and describes the efficacy and safety profile of some promising analgesic compounds. A deeper understanding of the molecular mechanisms behind both analgesic effects and adverse events could advance knowledge in this field, thus improving chronic pain treatment.

Buprenorphine Transdermal Delivery System: Bioequivalence Assessment and Adhesion Performance of Two Patch Formulations

Background and Objective: Buprenorphine is an opioid drug indicated for the management of severe and persistent pain. The buprenorphine transdermal patch provides a non-invasive method of rate-controlled drug release, ensuring constant and predictable drug plasma levels over an extended period. This study aimed to assess the bioequivalence, skin adhesion non-inferiority, and tolerability of two buprenorphine transdermal patches to meet the regulatory requirements for the registration of a generic product in Brazil. Methods: A randomized, single-dose, two-period, two-sequence crossover trial was performed involving healthy subjects of both genders. The subjects received a single dose of either the test formulation or the reference formulation (Restiva®), separated by a 29-day washout period. For pharmacokinetic analysis, blood samples were collected up to 12 days post-dose and quantified using a validated bioanalytical method. Skin adhesion was assessed over a 7-day period (dosing interval) following patch application. Seventy-six subjects were enrolled and fifty-two completed the study. Results and Conclusion: The 90% confidence intervals for Cmax, AUC0-t, and partial AUCs were within the acceptable bioequivalence limits of 80 to 125%. Adhesion comparison showed the non-inferiority of the test formulation. Based on ANVISA's regulatory requirements, the test and reference formulations were considered bioequivalent and could be interchangeable in clinical practice.

Long-term efficacy and reduced side-effects of buprenorphine in patients with moderate and severe chronic pain

Background

Chronic pain significantly impacts quality of life and poses substantial public health challenges. Buprenorphine, a synthetic analog of thebaine, is recognized for its potential in managing moderate to severe chronic pain with fewer side effects and a lower incidence of tolerance compared to traditional opioids.

Objective

This retrospective study aimed to assess the long-term efficacy and safety of buprenorphine transdermal patches in patients with moderate and severe chronic pain, with a focus on pain relief sustainability and tolerance development.

Methods

This retrospective observational study involved 246 patients prescribed buprenorphine transdermal patches. We evaluated changes in pain intensity using the Numeric Rating Scale (NRS), assessed opioid tolerance based on FDA guidelines for morphine-equivalent doses, and measured patient-reported outcomes through the Patients' Global Impression of Change (PGIC). Any adverse events were also recorded.

Results

Over the 36-month period, there was a significant reduction in NRS scores for both moderate and severe pain patients, demonstrating buprenorphine's sustained analgesic effect. Tolerance measurement indicated that no patients required increases in morphine-equivalent doses that would meet or exceed the FDA's threshold for opioid tolerance (60 mg/day of morphine or equivalent). Additionally, patient satisfaction was high, with the PGIC reflecting significant improvements in pain management and overall wellbeing. The side effects were minimal, with skin reactions and nausea being the most commonly reported but manageable adverse events.

Conclusion

The study findings validate the long-term use of buprenorphine transdermal patches as an effective and safe option for chronic pain management, maintaining efficacy without significant tolerance development. These results support the continued and expanded use of buprenorphine in clinical settings, emphasizing its role in reducing the burdens of chronic pain and opioid-related side effects. Further research is encouraged to refine pain management protocols and explore buprenorphine's full potential in diverse patient populations.

Opioid Maintenance Therapy: A Review of Methadone, Buprenorphine, and Naltrexone Treatments for Opioid Use Disorder

The rates of opioid use and opioid related deaths are escalating in the United States. Despite this, evidence-based treatments for Opioid Use Disorder are underutilized. There are three medications FDA approved for treatment of Opioid Use Disorder: Methadone, Buprenorphine, and Naltrexone. This article reviews the history, criteria, and mechanisms associated with Opioid Use Disorder. Pertinent pharmacology considerations, treatment strategies, efficacy, safety, and challenges of Methadone, Buprenorphine, and Naltrexone are outlined. Lastly, a practical decision making algorithm is discussed to address pertinent psychiatric and medical comorbidities when prescribing pharmacology for Opioid Use Disorder.

Serious treatment-emergent adverse events in chronic low back pain patients treated with buprenorphine or oral opioids: a retrospective commercial claims analysis

Aim: Explore the safety of Belbuca® (buprenorphine buccal film), buprenorphine transdermal patches and oral opioids for chronic low back pain (cLBP) treatment. Methods: The retrospective analysis of the MarketScan Commercial database (2018-2021) included treatment-naive cLBP adults. The first date of buprenorphine (Belbuca and transdermal patch) or opioid prescription was index date. Cohorts were defined based on the index medication. Observation included a 6-month pre-index period, while post-index lasted until the end of continuous insurance coverage. There were 44 relevant treatment-emergent adverse events (TEAEs) identified in the literature. Incidence rate ratio (IRR) and incidence rate difference (IRD) were used to compare serious TEAE rates (in 1000 person-years) between cohorts. Propensity-score matching minimized the selection bias. Results: Buprenorphine had lower rates of 15 serious TEAEs than oral opioids (all p ≤ 0.037), while higher rates only for serious dizziness (IRR 2.44, p = 0.011; driven by Belbuca), opioid abuse/dependence (IRR 3.13, p = 0.004; driven by patches) and cholecystitis (IRD 20.25, p = 0.044; an outlier). Additionally, a comparison between Belbuca and oral opioids showed lower rates of 13 serious TEAEs (all p ≤ 0.024) and a higher serious dizziness rate (IRR 3.17, p = 0.024). Although the rates of serious opioid abuse/dependence were similar (24.60 vs 26.93, p = 0.921), all Belbuca patients and none of the opioid patients had a positive history of these events. Belbuca also had lower rates of five serious TEAEs than transdermal patches (all p ≤ 0.018), including a serious opioid abuse/dependence (IRR 0.04, p < 0.001), but higher rates of serious cholecystitis (IRD 52.17, p = 0.035; an outlier) and suicidal ideation (IRD 156.50, p < 0.001; an outlier). Conclusion: Buprenorphine had a better safety profile than oral opioids in cLBP treatment. Belbuca showed a more favorable TEAE profile than buprenorphine transdermal patches and oral opioids.

Economic burden and dosing trends of buprenorphine buccal film and transdermal patch in chronic low back pain

Aim: Exploring prescribing trends and economic burden of chronic low back pain (cLBP) patients prescribed buprenorphine buccal film (Belbuca®) or transdermal patches. Methods: In the MarketScan® commercial insurance claims (employees and their spouses/dependents, 2018-2021), the first film or patch prescription date was an index event. The observation covered 6-month pre-index and 12-month post-index periods. Results: Patients were propensity-score matched (708 per cohort). Buprenorphine initiation had stable cost trends in buccal film and increasing trends in transdermal patch cohort. Between-cohort comparisons of healthcare expenditures, cost trends and resource utilization showed significant differences, mostly in favor of buccal film. Buccal film also had higher daily doses and wider dosing range. Conclusion: Buprenorphine film is more cost-effective cLBP treatment with more flexible dosing.

How Do I Manage Acute Pain for Patients Prescribed Buprenorphine for Opioid Use Disorder?

AbstractA growing number of patients are prescribed buprenorphine for opioid use disorder (OUD). Consequently, clinicians are likely to encounter hospitalized patients with acute surgical or nonsurgical pain who are also prescribed buprenorphine for OUD. This scenario evokes the clinical question of how to adequately manage acute pain among hospitalized patients receiving buprenorphine for OUD. This article reviews buprenorphine's pharmacology, describes various buprenorphine products used to treat pain and OUD, and provides pain management recommendations for patients prescribed buprenorphine in the setting of acute surgical and nonsurgical pain.

Post-operative pain control in patients on buprenorphine or methadone for opioid use disorder

OBJECTIVE

This study aimed to determine whether there is a difference in pain scores and opioid consumption after elective surgery in patients maintained on methadone or buprenorphine for opioid use disorder (OUD). Additionally, we investigated the impact of continuing or discontinuing methadone or buprenorphine on post-operative pain outcomes.

DESIGN

A single-center retrospective cohort study.

SETTING

Tertiary care medical center.

PATIENTS AND PARTICIPANTS

Adults aged 18 years or older with OUD maintained on buprenorphine or methadone who underwent elective surgery between January 1, 2017, and January 1, 2021.

INTERVENTIONS

Patients were identified through electronic medical records, and demographic and clinical data were collected.

MAIN OUTCOME MEASURES

The primary outcome was opioid consumption at 24 hours post-operatively, measured in milligram morphine equivalents. The secondary outcome was opioid consumption and pain scores up to 72 hours post-operatively, assessed using a numeric rating scale.

RESULTS

This study included 366 patients (64 percent on buprenorphine and 36 percent on methadone). Opioid utilization significantly increased when buprenorphine was not administered post-operatively. Both groups exhibited comparable total opioid consumption during the post-operative period. In the buprenorphine cohort, pain scores differed significantly based on the receipt of medications for OUD post-operatively.

CONCLUSIONS

This study reinforces existing evidence supporting the continuation of medications for opioid use disorder, specifically buprenorphine and methadone, during the perioperative period. Dissemination of guideline recommendations is essential to ensure optimal post-operative pain management for this patient population.

Pharmacokinetic-pharmacodynamic analysis of drug liking blockade by buprenorphine subcutaneous depot (CAM2038) in participants with opioid use disorder

Buprenorphine is used to treat opioid use disorder (OUD). Weekly and monthly subcutaneous long-acting buprenorphine injections (CAM2038) provide more stable buprenorphine plasma levels and reduce the treatment burden, misuse, and diversion associated with sublingual transmucosal buprenorphine formulations. To characterize the pharmacokinetic/pharmacodynamic (PK/PD) relationship, a maximum inhibition (Imax) model was developed relating CAM2038 buprenorphine plasma concentration to drug liking maximum effect (Emax) visual analog scale (VAS; bipolar) score after intramuscular hydromorphone administration. Data included time-matched observations of buprenorphine plasma concentration and drug liking Emax VAS score after hydromorphone 18 mg administration in 47 non-treatment-seeking adults with moderate to severe OUD in a phase 2 study. Analysis used non-‍linear mixed-effects modeling (NONMEM®). The final Imax model adequately described the PK/PD relationship between buprenorphine plasma concentration and drug liking Emax VAS score. Simulations showed drug liking was effectively blocked at low buprenorphine plasma concentrations (0.4 ng/mL) where the upper 95% confidence interval of the drug liking Emax VAS score was below the pre-defined 11-point complete blockade threshold. The buprenorphine plasma concentration required to achieve 90% of the maximal effect (IC90) of drug liking was 0.675 ng/mL. Interindividual variability in responses to buprenorphine was observed; some participants experienced fluctuating responses, and a few did not achieve drug liking blockade even with higher buprenorphine plasma concentrations. This affirms the need to individualize treatment and titrate doses for optimal treatment outcomes. PK/PD models were also developed for desire to use VAS and Clinical Opiate Withdrawal Scale (COWS) scores, with results aligned to those for drug liking.

Advances in animal models of prenatal opioid exposure

Neonatal opioid withdrawal syndrome (NOWS) is a growing public health concern. The complexity of in utero opioid exposure in clinical studies makes it difficult to investigate underlying mechanisms that could ultimately inform early diagnosis and treatments. Clinical studies are unable to dissociate the influence of maternal polypharmacy or the environment from direct effects of in utero opioid exposure, highlighting the need for effective animal models. Early animal models of prenatal opioid exposure primarily used the prototypical opioid, morphine, and opioid exposure that was often limited to a narrow period during gestation. In recent years, the number of preclinical studies has grown rapidly. Newer models utilize both prescription and nonprescription opioids and vary the onset and duration of opioid exposure. In this review, we summarize novel prenatal opioid exposure models developed in recent years and attempt to reconcile results between studies while critically identifying gaps within the current literature.

Buprenorphine for Pain: A Narrative Review and Practical Applications

Chronic noncancer pain affects about 20% of US adults and can significantly affect function and quality of life. Current guidelines recommend multimodal pain control. Despite risks associated with long-term opioid therapy, opioids are commonly prescribed. Buprenorphine is a partial opioid agonist with an improved safety profile compared to full agonists. Some formulations are approved for chronic pain and others for opioid use disorder. Buprenorphine is an option for patients who use chronic daily opioids for pain. This review summarizes the literature on buprenorphine's efficacy and safety for chronic pain and provides recommendations to generalists on initiation, titration, and monitoring of buprenorphine-based pain treatment. We also discuss a communication approach when considering buprenorphine for pain.

Unveiling the link between chronic pain and misuse of opioids and cannabis

Over 50 million Americans endure chronic pain where many do not receive adequate treatment and self-medicate to manage their pain by taking substances like opioids and cannabis. Research has shown high comorbidity between chronic pain and substance use disorders (SUD) and these disorders share many common neurobiological underpinnings, including hypodopaminergic transmission. Drugs commonly used for self-medication such as opioids and cannabis relieve emotional, bothersome components of pain as well as negative emotional affect that perpetuates misuse and increases the risk of progressing towards drug abuse. However, the causal effect between chronic pain and the development of SUDs has not been clearly established. In this review, we discuss evidence that affirms the proposition that chronic pain is a risk factor for the development of opioid and cannabis use disorders by outlining the clinical evidence and detailing neurobiological mechanisms that link pain and drug misuse. Central to the link between chronic pain and opioid and cannabis misuse is hypodopaminergic transmission and the modulation of dopamine signaling in the mesolimbic pathway by opioids and cannabis. Moreover, we discuss the role of kappa opioid receptor activation and neuroinflammation in the context of dopamine transmission, their contribution to opioid and cannabis withdrawal, along with potential new treatments.

Frontline Perspectives on Buprenorphine for the Management of Chronic Pain

Due to the prevalence of chronic pain and high-impact chronic pain in the US, a significant percentage of the population is prescribed opioids for pain management. However, opioid use disorder is associated with reduced quality of life, along with fatal opioid overdoses, and is a significant burden on the US economy. Considering the clinical needs of patients with intractable chronic pain and the potential harms associated with prescribed and illicit opioids in our communities, having a deep understanding of current treatment options, supporting evidence, and clinical practice guidelines is essential for optimizing treatment selections. Buprenorphine is a Schedule III opioid with a unique mechanism of action, allowing effective and long-lasting analgesia at microgram doses with fewer negative side effects and adverse events, including respiratory depression, when compared with other immediate-release, long-acting, and extended-release prescription opioids. Due to its relatively lower risk for overdose and misuse, buprenorphine was recently added to the Clinical Practice Guideline for the Use of Opioids in the Management of Chronic Pain as a first-line treatment for chronic pain managed by opioids by the US Departments of Defense and Veterans Affairs, and the Department of Health and Human Services recommends that buprenorphine be made available for the treatment of chronic pain. In this narrative review, we discuss the different buprenorphine formulations, clinical efficacy, advantages for older adults and other special populations, clinical practice guideline recommendations, and payer considerations of buprenorphine and suggest that buprenorphine products approved for chronic pain should be considered as a first-line treatment for this indication.

Considerations and limitations of buprenorphine prescribing for opioid use disorder in the intensive care unit setting: A narrative review

PURPOSE

The purpose of this review is to discuss important considerations when prescribing buprenorphine for opioid use disorder (OUD) in the intensive care unit (ICU) setting, recognizing the challenges of providing detailed recommendations in the setting of limited available evidence.

SUMMARY

Buprenorphine is a partial mu-opioid receptor agonist that is likely to be increasingly prescribed for OUD in the ICU setting due to the relaxation of prescribing regulations. The pharmacology and pharmacokinetics of buprenorphine are complicated by the availability of several formulations that can be given by different administration routes. There is no single optimal dosing strategy for buprenorphine induction, with regimens ranging from very low-dose to high dose regimens. Faster induction with higher doses of buprenorphine has been studied and is frequently utilized in the emergency department. In patients admitted to the ICU who were receiving opioids either medically or illicitly, analgesia will not occur until their baseline opioid requirements are covered when their preadmission opioid is either reversed or interrupted. For patients in the ICU who are not on buprenorphine at the time of admission but have possible OUD, there are no validated tools to diagnose OUD or the severity of opioid withdrawal in critically ill patients unable to provide the subjective components of instruments validated in outpatient settings. When prescribing buprenorphine in the ICU, important issues to consider include dosing, monitoring, pain management, use of adjunctive medications, and considerations to transition to outpatient therapy. Ideally, addiction and pain management specialists would be available when buprenorphine is prescribed for critically ill patients.

CONCLUSION

There are unique challenges when prescribing buprenorphine for OUD in critically ill patients, regardless of whether they were receiving buprenorphine when admitted to the ICU setting for OUD or are under consideration for buprenorphine initiation. There is a critical need for more research in this area.

Increasing buprenorphine access for patients with chronic pain: a quality improvement initiative

OBJECTIVE

Buprenorphine is effective for chronic pain and safer than full-agonist opioids; however, limited education about and support for buprenorphine can result in under-prescribing in primary care and reduced access in specialty pain clinics. The purpose of this quality improvement initiative was to optimize and evaluate procedures for transferring patients stable on buprenorphine for chronic pain from a specialty pain clinic back to primary care.

SETTING

Eight primary care clinics within a Veterans Health Administration health care system.

METHODS

A standard operating procedure for facilitated transfer of prescribing was developed after a needs assessment and was introduced during an educational session with primary care providers, and providers completed a survey assessing attitudes about buprenorphine prescribing. Success of the initiative was measured through the number of patients transferred back to primary care over the course of 18 months.

RESULTS

Survey results indicated that primary care providers with previous experience prescribing buprenorphine were more likely to view buprenorphine prescribing for pain as within the scope of their practice and to endorse feeling comfortable managing a buprenorphine regimen. Providers identified systemic and educational barriers to prescribing, and they identified ongoing support from specialty pain care and primary care as a facilitator of prescribing. Metrics suggested that the standard operating procedure was generally successful in transferring and retaining eligible patients in primary care.

CONCLUSION

This quality improvement initiative suggests that a facilitated transfer procedure can be useful in increasing buprenorphine prescribing for pain in primary care. Future efforts to increase primary care provider comfort and address systemic barriers to buprenorphine prescribing are needed.

PHARMACOKINETICS OF TRAMADOL AND O-DESMETHYLTRAMADOL IN GIANT TORTOISES (CHELONOIDIS VANDENBURGHI, CHELONOIDIS VICINA)

The objective of this study was to determine the pharmacokinetics of two orally administered doses of tramadol (1 mg/kg and 5 mg/kg) and its metabolite, O-desmethyltramadol (M1) in giant tortoises (Chelonoidis vandenburghi, Chelonoidis vicina). Eleven giant tortoises (C. vandenburghi, C. vicina) received two randomly assigned, oral doses of tramadol (either 1 mg/kg or 5 mg/kg), with a washout period of 3 wk between each dose. The half-life (t½) of orally administered tramadol at 1 mg/kg and 5 mg/kg was 11.9 ± 4.6 h and 13.2 ± 6.1 h, respectively. After oral administration of tramadol at 1 mg/kg and 5 mg/kg, the maximum concentration (Cmax) was 125 ± 69 ng/ml and 518 ± 411 ng/ml, respectively. There were not enough data points to determine pharmacokinetic (PK) parameters for the M1 metabolite from either dose. Tramadol administered orally to giant tortoises at both doses provided measurable plasma concentrations of tramadol for approximately 48 h with occasional transient sedation. Oral tramadol at 5 mg/kg, on average, achieves concentrations of >100 ng/ml, the reported human therapeutic threshold, for 24 h. Based on the low levels of M1 seen in this study, M1 may not be a major metabolite in this taxon.

Barriers and Best Practices on the Management of Opioid Use Disorder

Opioids refer to chemicals that agonize opioid receptors in the body resulting in analgesia and sometimes, euphoria. Opiates include morphine and codeine; semi-synthetic opioids include heroin, hydrocodone, oxycodone, and buprenorphine; and fully synthetic opioids include tramadol, fentanyl and methadone. In 2021, an estimated 5.6 million individuals met criteria for opioid use disorder. This article provides an overview of the pharmacology of heroin and non-prescription fentanyl (NPF) and its synthetic analogues, and summarizes the literature related to the management of opioid use disorder, overdose, and withdrawal. This is followed by a description of barriers to treatment and best practices for management with a discussion on recent updates and their potential impact on this patient population. This is followed by a description of barriers to treatment and best practices for management with a discussion on recent updates and their potential impact on this patient population.

Low-dose buprenorphine initiation and treatment continuation among hospitalized patients with opioid dependence: A retrospective cohort study

BACKGROUND

Buprenorphine is an effective treatment for both opioid use disorder (OUD) and chronic pain, but buprenorphine's pharmacology complicates treatment initiation for some patients. Low-dose buprenorphine initiation is a novel strategy that may reduce precipitated withdrawal. Few studies describe what patient populations benefit most from low-dose initiations and the clinical parameters that impact treatment continuation. This study aimed to 1) describe experiences with low-dose buprenorphine initiation, including both successes and failures among hospitalized patients in an urban underserved community; 2) identify patient- and treatment-related characteristics associated with unsuccessful initiation and treatment discontinuation; and 3) assess buprenorphine treatment continuation after discharge.

METHODS

This is a retrospective cohort study with opioid-dependent (meaning OUD or receiving long-term opioid therapy for chronic pain) patients who underwent low-dose buprenorphine initiation during hospital admission from October 2021 through April 2022. The primary outcome was successful completion of low-dose initiation. Bivariate analysis identified patient- and treatment-related factors associated with unsuccessful initiation. Secondary outcomes were buprenorphine treatment discontinuation at post-discharge follow-up, 30- and 90-days.

RESULTS

Of 28 patients who underwent low-dose buprenorphine initiation, 68 % successfully completed initiation. Unsuccessful initiation was associated with receipt of methadone during admission and higher morphine milligram equivalents (MME) of supplemental opioids. Of 22 patients with OUD, the percent receiving a buprenorphine prescription at a follow-up visit, 30 days, and 90 days, respectively, was 46 %, 36 %, and 36 %. Of 6 patients with chronic pain, the percent receiving a buprenorphine prescription at a follow-up visit, 30 days, and 90 days, respectively, was 100 %, 100 %, and 83 %.

CONCLUSION

Low-dose buprenorphine initiation can be successful in opioid-dependent hospitalized patients. Patients taking methadone or requiring higher MME of supplemental opioids may have more difficulty with the low-dose buprenorphine initiation approach, but these findings should be replicated in larger studies. This study suggests patient- and treatment-related factors that clinicians could consider when determining the optimal treatment strategy for patients wishing to transition to buprenorphine.

Management of Critically Ill Patients Receiving Medications for Opioid Use Disorder

TOPIC IMPORTANCE

Critical care clinicians are likely to see an increasing number of patients admitted to the ICU who are receiving US Food and Drug Administration-approved medications for opioid use disorder (MOUDs) given the well-documented benefits of these agents. Oral methadone, multiple formulations of buprenorphine, and extended-release naltrexone are the three types of MOUD most likely to be encountered by ICU clinicians; however, these drugs vary with respect to formulations, pharmacokinetics, and adverse effects.

REVIEW FINDINGS

No published clinical practice guidelines or consensus statements are available to guide decision-making in patients admitted to the ICU setting who are receiving MOUDs before admission. Additionally, no randomized trials and limited observational studies have evaluated issues related to MOUD use in the ICU. Therefore, ICU clinicians caring for patients admitted who are taking MOUDs must base their decision-making on data extrapolation from pharmacokinetic, pharmacologic, and clinical studies performed in non-ICU settings.

SUMMARY

Despite the challenges in administering MOUDs in critically ill patients, extrapolation of data from other hospital settings suggests that the benefits of continuing MOUD therapy outweigh the risks in patients able to continue therapy. This article provides guidance for critical care clinicians caring for patients admitted to the ICU already receiving methadone, buprenorphine, or extended-release naltrexone. The guidance includes algorithms to aid clinicians in the clinical decision-making process, recognizing the inherent limitations of the existing evidence on which the algorithms are based and the need to account for patient-specific considerations.

Chronic opioid pain treatment converted to buprenorphine: A case series using a 3-step low-dose incremental dosing guideline

We report a 30-case series from the Pain Management Center at the Massachusetts General Hospital where we have applied a guideline to convert chronic treatment for pain from full agonist opioids (FAO) to buprenorphine (BUP). Of the patients, 24 (80 percent) elected to continue BUP over FAO. Five conversions were stopped for side effects (fatigue) and/or lack of sufficient pain reduction. One patient elected not to participate on the day that the conversion was to begin. There were no major adverse events. We conclude that conversion to BUP should be considered as an alternative to treat patients on chronic opioids for pain.

A Guide to Expanding the Use of Buprenorphine Beyond Standard Initiations for Opioid Use Disorder

Buprenorphine has become an important medication in the context of the ongoing opioid epidemic. However, complex pharmacologic properties and varying government regulations create barriers to its use. This narrative review is intended to facilitate buprenorphine use-including non-traditional initiation methods-by providers ranging from primary care providers to addiction specialists. This article briefly discusses the opioid epidemic and the diagnosis and treatment of opioid use disorder (OUD). We then describe the basic and complex pharmacologic properties of buprenorphine, linking these properties to their clinical implications. We guide readers through the process of initiating buprenorphine in patients using full agonist opioids. As there is no single recommended approach for buprenorphine initiation, we discuss the details, advantages, and disadvantages of the standard, low-dose, bridging-strategy, and naloxone-facilitated initiation techniques. We consider the pharmacology of, and evidence base for, buprenorphine in the treatment of pain, in both OUD and non-OUD patients. Throughout, we address the use of buprenorphine in children and adolescent patients, and we finish with considerations related to the settings of pregnancy and breastfeeding.

Outpatient cross-titration to buprenorphine for chronic pain: A retrospective analysis

OBJECTIVE

To determine the effectiveness and safety of the University of Washington's buprenorphine cross-titration protocol for chronic pain in the outpatient setting.

METHODS

Retrospective chart review was performed on 150 patients transitioned from full µ-opioid agonist therapy to buprenorphine using the University of Washington Medical Center Pain Clinic's cross-titration protocol between September 1, 2020, and December 31, 2021, in an outpatient setting. Primary outcome was to determine the percentage of patients who completed the cross-titration and continued buprenorphine without full µ-opioid agonists 4 weeks after completion. Secondary outcomes included final buprenorphine dose, days needed to complete cross-titration, deviation rates from the protocol, and opioid-related adverse events.

RESULTS

Fifteen of 31 (48.4 percent) included patients successfully converted to buprenorphine. Median duration of successful cross-titration was 29 days (interquartile range 19-57). Average end-titration dose for patients on buprenorphine/naloxone sublingual films was 7.9 ± 5.7 mg/day, while for buprenorphine transdermal (TD) patches, it was 11.9 ± 4.8 mcg/h. Morphine equivalent daily dose (MEDD) prior to induction varied widely. All patients transitioned to TD buprenorphine were taking ≤30 mg MEDD. Patients previously taking >120 mg MEDD stabilized on 8-16 mg/day buprenorphine. Most common reasons for cross-titration failure were inadequate pain control and intolerable adverse effects.

DISCUSSION

The University of Washington's buprenorphine cross-titration protocol for chronic pain was successful in about half of included patients undergoing conversion from chronic full µ-opioid agonist therapy and generally well tolerated. Clinical responses were widely variable, and many required slower taper and higher end-titration buprenorphine dose than anticipated. Although protocols provide structure for cross-titration, each course should be monitored closely and individualized.

Acute Pain Management for Patients Maintained on Sublingual Buprenorphine as Medication for Opioid Use Disorder

OBJECTIVE

The aim of this study was to compare morphine milligram equivalent (MME) requirements for acute pain management between patients admitted for medical or surgical diagnoses with opioid use disorder (OUD) who receive >12 mg of sublingual buprenorphine daily compared with those who receive ≤12 mg/d.

DESIGN

This study was performed via retrospective chart review.

SETTING

This study evaluated patient encounters between January 2017 and November 2021 from a single-center community teaching hospital in Lancaster, PA.

METHODS

Patients were assessed according to daily dose of buprenorphine received while admitted (>12 mg/d vs ≤12 mg/d); patients who had buprenorphine held were included within the ≤12 mg/d study group. The primary outcome evaluated daily average MME requirements over the entirety of hospital length of stay. Key secondary outcomes were total MME requirements and daily average pain scores.

SUBJECTS

Key inclusion criteria were sublingual buprenorphine therapy for at least 1 month prior to admission, presence of an acute pain diagnosis during hospital stay, and history of OUD.

RESULTS

Seventy-eight (78) patients were included for analysis. Daily average MME requirements were similar between patients who received buprenorphine >12 mg/d and ≤12 mg/d (median, 7.5 vs 10.6; P = 0.350). Total MME and daily average pain scores were similar between study groups.

CONCLUSIONS

For OUD patients in need of acute pain management, the continuation of sublingual buprenorphine throughout hospitalization at a daily dose of >12 mg/d compared with ≤12 mg/d did not confer a significant difference in daily average MME requirements.

An Examination of the Complex Pharmacological Properties of the Non-Selective Opioid Modulator Buprenorphine

The goal of this review is to provide a recent examination of the pharmacodynamics as well as pharmacokinetics, misuse potential, toxicology, and prenatal consequences of buprenorphine. Buprenorphine is currently a Schedule III opioid in the US used for opioid-use disorder (OUD) and as an analgesic. Buprenorphine has high affinity for the mu-opioid receptor (MOR), delta (DOR), and kappa (KOR) and intermediate affinity for the nociceptin (NOR). Buprenorphine's active metabolite, norbuprenorphine, crosses the blood-brain barrier, is a potent metabolite that attenuates the analgesic effects of buprenorphine due to binding to NOR, and is responsible for the respiratory depressant effects. The area under the concentration curves are very similar for buprenorphine and norbuprenorphine, which indicates that it is important to consider this metabolite. Crowding sourcing has identified a buprenorphine street value (USD 3.95/mg), indicating some non-medical use. There have also been eleven-thousand reports involving buprenorphine and minors (age < 19) at US poison control centers. Prenatal exposure to clinically relevant dosages in rats produces reductions in myelin and increases in depression-like behavior. In conclusion, the pharmacology of this OUD pharmacotherapy including the consequences of prenatal buprenorphine exposure in humans and experimental animals should continue to be carefully evaluated.

Population Pharmacokinetic Analysis Supports Initiation Treatment and Bridging from Sublingual Buprenorphine to Subcutaneous Administration of a Buprenorphine Depot (CAM2038) in the Treatment of Opioid Use Disorder

BACKGROUND AND OBJECTIVE

In treating opioid use disorder (OUD), subcutaneous (SC) extended-release buprenorphine (BPN) depots, e.g., CAM2038, have been shown to provide smaller and less frequent fluctuations in BPN plasma concentrations and pharmacodynamic responses, improve outcomes, reduce treatment burden, and lower risks of misuse and diversion compared to daily sublingual (SL) BPN. This analysis characterized the pharmacokinetics (PK) of BPN following intravenous and SL administration, and administration of SC CAM2038 weekly and monthly.

METHODS

Pharmacokinetic data from two Phase 1 and two Phase 2 trials in healthy participants and participants with OUD, respectively, were used to develop a population PK model using non-linear mixed effects modelling. The analysis included data from 252 participants and 10,658 BPN observations.

RESULTS

The disposition of BPN was best described by a three-compartment model with first-order elimination, and absorption of SL BPN and SC CAM2038 weekly and monthly by dual parallel absorption pathways. Model diagnostics indicated good predictive performance of BPN concentrations. Buprenorphine plasma concentration-time profiles were simulated for treatment initiation, switching from SL BPN to CAM2038 weekly and monthly, and tapering after interrupting treatment with CAM2038. Simulations predicted CAM2038 weekly and monthly doses that provided BPN plasma maximum concentration (Cmax) and trough concentration (Ctrough) values at steady state within those observed following SL BPN administration.

CONCLUSIONS

This population PK model supports the use of CAM2038 doses as individualized treatment for OUD across different treatment stages, including initiation, switching from SL BPN according to established dose conversion schedules, and tapering.

TRIAL REGISTRATIONS

ISRCTN41550730 (05/19/2014), ISRCTN24987553 (07/29/2014), NCT02611752 (11/23/2015), NCT02710526 (03/16/2016).

Research Priorities for Expansion of Opioid Use Disorder Treatment in the Community Pharmacy

In the last decade, the U.S. opioid overdose crisis has magnified, particularly since the introduction of synthetic opioids, including fentanyl. Despite the benefits of medications for opioid use disorder (MOUD), only about a fifth of people with opioid use disorder (OUD) in the U.S. receive MOUD. The ubiquity of pharmacists, along with their extensive education and training, represents great potential for expansion of MOUD services, particularly in community pharmacies. The National Institute on Drug Abuse's National Drug Abuse Treatment Clinical Trials Network (NIDA CTN) convened a working group to develop a research agenda to expand OUD treatment in the community pharmacy sector to support improved access to MOUD and patient outcomes. Identified settings for research include independent and chain pharmacies and co-located pharmacies within primary care settings. Specific topics for research included adaptation of pharmacy infrastructure for clinical service provision, strategies for interprofessional collaboration including health service models, drug policy and regulation, pharmacist education about OUD and OUD treatment, including didactic, experiential, and interprofessional curricula, and educational interventions to reduce stigma towards this patient population. Together, expanding these research areas can bring effective MOUD to where it is most needed.

Long-Acting Buprenorphine Formulations as a New Strategy for the Treatment of Opioid Use Disorder

Long-acting buprenorphine formulations have been recently marketed for the Opioid Agonist Treatment (OAT) of opioid use disorder (OUD) associated with medical, social, and psychological support. Their duration of action ranges from one week up to 6 months. The non-medical use of opioids is increasing with a parallel rise in lethal overdoses. Methadone and buprenorphine are the standard treatment for opioid dependence. Methadone Maintenance Treatment (MMT) is widely recognized as one of the most effective ways of reducing the risks of overdose, crime, and transmission of HIV (Human Immunodeficiency Virus) in people who use opioids; however, its effectiveness has been hindered by low rates of uptake and retention in treatment. Furthermore, both methadone and buprenorphine are widely diverted and misused. Thus, a crucial aspect of treating OUD is facilitating patients' access to treatment while minimizing substance-related harm and improving quality of life. The newly developed long-acting buprenorphine formulations represent a significant change in the paradigm of OUD treatment, allowing an approach individualized to patients' needs. Strengths of this individualized approach are improved adherence (lack of peaks and troughs in blood concentrations) and a reduced stigma since the patient doesn't need to attend their clinic daily or nearly daily, thus facilitating social and occupational integrations as the quality of life. However, less frequent attendance at the clinic should not affect the patient-physician relationship. Therefore, teleconsulting or digital therapeutic services should be developed in parallel. In addition, diversion and intravenous misuse of buprenorphine are unlikely due to the characteristics of these formulations. These features make this approach of interest for treating OUD in particular settings, such as subjects staying or when released from prison or those receiving long-term residential treatment for OUD in the therapeutic communities. The long-lasting formulations of buprenorphine can positively impact the OUD treatment and suggest future medical and logistic developments to maximize their personalized management and impact.

Compassionate Care for People with Cancer and Opioid Use Disorder

ABSTRACT

Opioid use disorder (OUD) is an important comorbidity to assess and manage in people with cancer. In this article, the authors discuss strategies for safe opioid management in individuals with OUD and cancer-related pain using a composite case example. They highlight core approaches to pain management, including motivational interviewing, harm reduction, and evidence-based treatments, as well as advocacy for person-centered end-of-life care.

Patients' experiences with continuation or discontinuation of buprenorphine before painful procedures: A brief report

BACKGROUND AND OBJECTIVES

Patients with opioid use disorder may be asked by their clinicians to discontinue maintenance buprenorphine treatment before surgical operations due to concerns that buprenorphine will interfere with acute pain management. However, discontinuation of buprenorphine may not be well tolerated or safe for all patients. We, therefore, administered a survey to better understand the experiences of patients on buprenorphine treatment who had previously undergone painful procedures and had their buprenorphine maintenance treatment either continued or discontinued before the procedure.

METHODS

After this study received institutional review board approval, patients were invited to participate if they were being prescribed sublingual buprenorphine for treatment of opioid use disorder and had also previously undergone a painful procedure requiring treatment with full agonist opioids. Patients who were eligible and agreed to participate (n = 32) then completed a survey of basic demographics; medical, psychiatric, and substance use histories; and their experience and satisfaction with the treatment of pain and substance use in the perioperative period, including whether buprenorphine was continued or discontinued before their procedure.

RESULTS

Compared with patients whose home dose of buprenorphine was continued (n = 15), patients whose buprenorphine was discontinued preoperatively (n = 17) reported less satisfaction with pain management and were more likely to be prescribed full agonist opioids upon discharge.

DISCUSSION AND CONCLUSIONS

Consistent with prior studies, these survey findings suggest that discontinuation of buprenorphine before painful surgeries may be associated with poorer clinical outcomes.

SCIENTIFIC SIGNIFICANCE

This survey study adds patients' perspective to a growing body of scientific literature suggesting that discontinuation of maintenance buprenorphine treatment before painful procedures may decrease patient satisfaction and increase clinical risk.

Structural basis of efficacy-driven ligand selectivity at GPCRs

A drug's selectivity for target receptors is essential to its therapeutic utility, but achieving selectivity between similar receptors is challenging. The serendipitous discovery of ligands that stimulate target receptors more strongly than closely related receptors, despite binding with similar affinities, suggests a solution. The molecular mechanism of such 'efficacy-driven selectivity' has remained unclear, however, hindering design of such ligands. Here, using atomic-level simulations, we reveal the structural basis for the efficacy-driven selectivity of a long-studied clinical drug candidate, xanomeline, between closely related muscarinic acetylcholine receptors (mAChRs). Xanomeline's binding mode is similar across mAChRs in their inactive states but differs between mAChRs in their active states, with divergent effects on active-state stability. We validate this mechanism experimentally and use it to design ligands with altered efficacy-driven selectivity. Our results suggest strategies for the rational design of ligands that achieve efficacy-driven selectivity for many pharmaceutically important G-protein-coupled receptors.

Analgesic Effect of Buprenorphine for Chronic Noncancer Pain: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

Buprenorphine is a partial agonist at the µ-opioid receptor and an antagonist at the delta and kappa opioid receptors. It has high affinity and low intrinsic activity at the µ-opioid receptor. Buprenorphine demonstrates no ceiling effect for clinical analgesia, but demonstrates this for respiratory depression and euphoria. It may provide effective analgesia while producing less adverse effects, making it a promising opioid analgesic. A systematic review and meta-analysis were performed to examine the analgesic efficacy of buprenorphine for patients with chronic noncancer pain.

METHODS

PubMed, MEDLNE, Embase, and the Cochrane Library were searched up to January 2022. Randomized controlled trials were included if they compared buprenorphine versus placebo or active analgesic in patients with chronic noncancer pain, where pain score was an outcome. Nonrandomized controlled trials, observational studies, qualitative studies, case reports, and commentaries were excluded. Two investigators independently performed the literature search, study selection, and data collection. A random-effects model was used. The primary outcome was the effect of buprenorphine on pain intensity in patients with chronic noncancer pain based on standardized mean difference (SMD) in pain score. Quality of evidence was assessed using the Grade of Recommendations Assessment, Development, and Evaluation (GRADE) approach.

RESULTS

Two separate literature searches were conducted for patients with and without opioid use disorder (OUD). Only one study met the search criteria for those with OUD. Fourteen randomized controlled trials were included for those without OUD. Buprenorphine was associated with reduced pain score (SMD = -0.368, P < .001, I 2 = 89.37%) compared to placebo or active analgesic. Subgroup meta-analyses showed statistically significant differences in favor of buprenorphine versus placebo (SMD = -0.404, P < .001), for chronic low back pain (SMD = -0.383, P < .001), when administered via the transdermal route (SMD = -0.572, P = .001), via the buccal route (SMD = -0.453, P < .001), with length of follow-up lasting <12 weeks (SMD = -0.848, P < .05), and length of follow-up lasting 12 weeks or more (SMD = -0.415, P < .001). There was no significant difference when compared to active analgesic (SMD = 0.045, P > .05). Quality of evidence was low to moderate.

CONCLUSIONS

Buprenorphine was associated with a statistically significant and small reduction in pain intensity compared to placebo. Both the transdermal and buccal routes provided pain relief. There was more evidence supporting its use for chronic low back pain.

Sublingual/Buccal buprenorphine and dental problems: a pharmacovigilance study

BACKGROUND

The association between dental problems and sublingual/buccal buprenorphine is unclear. We conducted an analysis of dental adverse drug reactions reported with sublingual/buccal buprenorphine in VigiBase®, the pharmacovigilance database of the World Health Organization.

RESEARCH DESIGN AND METHODS

We performed disproportionality analyses to compare the reporting rates of dental problems with sublingual/buccal buprenorphine, compared to other buprenorphine formulations and methadone. Significant signals were considered if the lower boundary of the 95% confidence interval of the Reporting Odds Ratio (ROR) was > 1; cases were ≥ 3 and p-value <0.05. We conducted sensitivity analyses by calculating the ROR according to the reporter's qualification and the reporting continent (United States of America and Europe).

RESULTS

We included 30,769 reports with all buprenorphine forms. We found 20 cases of dental problems with sublingual/buccal buprenorphine. Sublingual/buccal buprenorphine was associated with an overreporting of dental problems compared to other buprenorphine formulations (ROR = 15.10; 95% CI [7.50-30.39]; p < 0.005) and compared to methadone (ROR = 6.02; 95% CI [3.21-11.30]; p < 0.005). Overreporting of dental problems was consistent in sensitivity analyses, except in Europe compared with other buprenorphine formulations and with methadone.

CONCLUSIONS

Sublingual/buccal buprenorphine might increase the risk of reporting dental problems. However, these results do not modify the benefits of sublingual/buccal buprenorphine in the treatment of opioid use disorders.

Opioids and opioid receptors; understanding pharmacological mechanisms as a key to therapeutic advances and mitigation of the misuse crisis

Opioids are a mainstay in acute pain management and produce their effects and side effects (e.g., tolerance, opioid-use disorder and immune suppression) by interaction with opioid receptors. I will discuss opioid pharmacology in some controversial areas of enquiry of anaesthetic relevance. The main opioid target is the µ (mu,MOP) receptor but other members of the opioid receptor family, δ (delta; DOP) and κ (kappa; KOP) opioid receptors also produce analgesic actions. These are naloxone-sensitive. There is important clinical development relating to the Nociceptin/Orphanin FQ (NOP) receptor, an opioid receptor that is not naloxone-sensitive. Better understanding of the drivers for opioid effects and side effects may facilitate separation of side effects and production of safer drugs. Opioids bind to the receptor orthosteric site to produce their effects and can engage monomer or homo-, heterodimer receptors. Some ligands can drive one intracellular pathway over another. This is the basis of biased agonism (or functional selectivity). Opioid actions at the orthosteric site can be modulated allosterically and positive allosteric modulators that enhance opioid action are in development. As well as targeting ligand-receptor interaction and transduction, modulating receptor expression and hence function is also tractable. There is evidence for epigenetic associations with different types of pain and also substance misuse. As long as the opioid narrative is defined by the 'opioid crisis' the drive to remove them could gather pace. This will deny use where they are effective, and access to morphine for pain relief in low income countries.

Analgesic Effects of Fisetin, Peimine, Astaxanthin, Artemisinin, Bardoxolone Methyl and 740 Y-P and Their Influence on Opioid Analgesia in a Mouse Model of Neuropathic Pain

Treatment of neuropathic pain remains a challenge for modern medicine due to the insufficiently understood molecular mechanisms of its development and maintenance. One of the most important cascades that modulate the nociceptive response is the family of mitogen-activated protein (MAP) kinases and phosphatidylinositol-3-kinase (PI3K), as well as nuclear factor erythroid 2-related factor 2 (Nrf2). The aim of this study was to determine the effect of nonselective modulators of MAP kinases-fisetin (ERK1/2 and NFκB inhibitor, PI3K activator), peimine (MAPK inhibitor), astaxanthin (MAPK inhibitor, Nrf2 activator) and artemisinin (MAPK inhibitor, NFκB activator), as well as bardoxolone methyl (selective activator of Nrf2) and 740 Y-P (selective activator of PI3K)-in mice with peripheral neuropathy and to compare their antinociceptive potency and examine their effect on analgesia induced by opioids. The study was performed using albino Swiss male mice that were exposed to chronic constriction injury of the sciatic nerve (CCI model). Tactile and thermal hypersensitivity was measured using von Frey and cold plate tests, respectively. Single doses of substances were administered intrathecally on day 7 after CCI. Among the tested substances, fisetin, peimine, and astaxanthin effectively diminished tactile and thermal hypersensitivity in mice after CCI, while artemisinin did not exhibit analgesic potency in this model of neuropathic pain. Additionally, both of the activators tested, bardoxolone methyl and 740 Y-P, also showed analgesic effects after intrathecal administration in mice exposed to CCI. In the case of astaxanthin and bardoxolone methyl, an increase in analgesia after combined administration with morphine, buprenorphine, and/or oxycodone was observed. Fisetin and peimine induced a similar effect on tactile hypersensitivity, where analgesia was enhanced after administration of morphine or oxycodone. In the case of 740 Y-P, the effects of combined administration with each opioid were observed only in the case of thermal hypersensitivity. The results of our research clearly indicate that substances that inhibit all three MAPKs provide pain relief and improve opioid effectiveness, especially if they additionally block NF-κB, such as peimine, inhibit NF-κB and activate PI3K, such as fisetin, or activate Nrf2, such as astaxanthin. In light of our research, Nrf2 activation appears to be particularly beneficial. The abovementioned substances bring promising results, and further research on them will broaden our knowledge regarding the mechanisms of neuropathy and perhaps contribute to the development of more effective therapy in the future.