Buprenorphine: Far Beyond the "Ceiling"

Orally dissolving buprenorphine for opioid use disorder linked to caries

BACKGROUND

Buprenorphine is under scrutiny because of the development of xerostomia and caries. The purpose of this article was to inform dental care professionals about the oral effects of buprenorphine and to increase knowledge and awareness of medication-assisted treatment in the management of opioid use disorder (OUD).

CASE DESCRIPTION

In 2022, the US Food and Drug Administration issued a warning about xerostomia and caries associated with the use of transmucosal (sublingual and buccal formulations) buprenorphine. Dental health care professionals should instruct patients taking buprenorphine on how to prevent these dental issues by means of rinsing with water and swallowing once the drug has been completely dissolved, followed by toothbrushing at least 1 hour after taking the drug. In addition, a fluoride supplement should be prescribed.

PRACTICAL IMPLICATIONS

It is imperative for dentists to recognize buprenorphine as medication-assisted treatment and to recognize a patient as having an OUD. While taking buprenorphine, the patient should have regular oral health care appointments, including home care instructions and caries risk assessment to monitor for caries and xerostomia so that treatment, if indicated, could be initiated as soon as possible. In addition, the dentist's role in OUD is to make sure patients follow the treatment recommendations and use the buprenorphine and to not have them discontinue because of potential caries risk.

Quantifying a potential protective effect of buprenorphine on fatality risk during acute fentanyl exposures

INTRODUCTION

Buprenorphine is an important therapy for opioid use disorder and may also reduce the risk of fatal overdoses in fentanyl exposures. However, the role of buprenorphine in reducing this risk has not been quantified. This cross-sectional study examined the association between buprenorphine presence, decedent characteristics, and other factors with the predicted fentanyl concentrations in overdose deaths.

METHODS

The study identified unintentional fentanyl overdose decedents (n = 3036) from the West Virginia Forensic Drug Database, 2011 through mid-2020. The main outcome was fentanyl concentrations in overdose deaths in the presence and absence of buprenorphine. A multiple linear regression model examined the association of fentanyl concentrations with buprenorphine presence based on the concentrations of the parent drug buprenorphine (B) and its metabolite norbuprenorphine (N), adjusting for demographics, toxicological characteristics (presence of multiple opioids, benzodiazepines, stimulants, marijuana, and alcohol), and comorbidities. We used a B/N concentration ratio < 1 as an indirect indicator of longer-term buprenorphine exposure prior to drug overdose death.

RESULTS

The median fentanyl concentration was 65 % higher when buprenorphine was present (N = 168) vs. absent (N = 2868) (0.028 vs. 0.017 μg/mL, p < 0.001). In the multivariable model, statistically significant associations occurred between buprenorphine presence and increased fentanyl concentrations (+28.7 %) with a B/N ratio < 1. Obesity, male sex, alcohol presence, and comorbid cardiovascular diseases were statistically significantly associated with lower (-11.3 % to -20.7 %) fentanyl concentrations, whereas marijuana presence and a history of substance use disorder were associated with statistically significant higher fentanyl concentrations (+8.8 % to +31.3 %).

CONCLUSIONS

These findings suggest that sustained or longer-term buprenorphine intake might exert some protective effect on fatalities resulting from fentanyl exposure as documented by the association of higher fentanyl blood concentrations with buprenorphine presence among fatal drug overdoses. As fentanyl availability and overdose rates increase nationally, buprenorphine is a vital tool for effective opioid use disorder treatment that might also reduce the risk of fatality in an acute fentanyl exposure.

Buprenorphine for Chronic Pain Management: a Narrative Review

PURPOSE OF REVIEW

The aim of this review is to educate healthcare professionals regarding buprenorphine for the use of opioid use disorder (OUD) as well as for chronic pain management. This review provides physicians and practitioners with updated information regarding the distinct characteristics and intricacies of prescribing buprenorphine.

RECENT FINDINGS

Buprenorphine is approved by the US Food and Drug Administration (FDA) for acute pain, chronic pain, opioid use disorder (OUD), and opioid dependence. When compared to most other opioids, buprenorphine offers superior patient tolerability, an excellent half-life, and minimal respiratory depression. Buprenorphine does have notable side effects as well as pharmacokinetic properties that require special attention, especially if patients require future surgical interventions. Many physicians are not trained to initiate or manage patients on buprenorphine. However, buprenorphine offers a potentially safer alternative for medication management for patients who require chronic opioid therapy for pain or have OUD. This review provides updated information on buprenorphine for both chronic pain and OUD.

Validation of a pharmacological imaging challenge using 11C-buprenorphine and 18F-2-fluoro-2-deoxy-D-glucose positron emission tomography to study the effects of buprenorphine to the rat brain

Aim

Buprenorphine mainly acts as an agonist of mu-opioid receptors (mu-OR). High dose buprenorphine does not cause respiratory depression and can be safely administered to elicit typical opioid effects and explore pharmacodynamics. Acute buprenorphine, associated with functional and quantitative neuroimaging, may therefore provide a fully translational pharmacological challenge to explore the variability of response to opioids in vivo. We hypothesized that the CNS effects of acute buprenorphine could be monitored through changes in regional brain glucose metabolism, assessed using ¹⁸F-FDG microPET in rats.

Materials and methods

First, level of receptor occupancy associated with a single dose of buprenorphine (0.1 mg/kg, s.c) was investigated through blocking experiments using ¹¹C-buprenorphine PET imaging. Behavioral study using the elevated plus-maze test (EPM) was performed to assess the impact of the selected dose on anxiety and also locomotor activity. Then, brain PET imaging using ¹⁸F-FDG was performed 30 min after injection of unlabeled buprenorphine (0.1 mg/kg, s.c) vs. saline. Two different ¹⁸F-FDG PET acquisition paradigms were compared: (i) ¹⁸F-FDG injected i.v. under anesthesia and (ii) ¹⁸F-FDG injected i.p. in awake animals to limit the impact of anesthesia.

Results

The selected dose of buprenorphine fully blocked the binding of ¹¹C-buprenorphine in brain regions, suggesting complete receptor occupancy. This dose had no significant impact on behavioral tests used, regardless of the anesthetized/awake handling paradigm. In anesthetized rats, injection of unlabeled buprenorphine decreased the brain uptake of ¹⁸F-FDG in most brain regions except in the cerebellum which could be used as a normalization region. Buprenorphine treatment significantly decreased the normalized brain uptake of ¹⁸F-FDG in the thalamus, striatum and midbrain (p < 0.05), where binding of ¹¹C-buprenorphine was the highest. The awake paradigm did not improve sensitivity and impact of buprenorphine on brain glucose metabolism could not be reliably estimated.

Conclusion

Buprenorphine (0.1 mg/kg, s.c) combined with ¹⁸F-FDG brain PET in isoflurane anesthetized rats provides a simple pharmacological imaging challenge to investigate the CNS effects of full receptor occupancy by this partial mu-OR agonist. Sensitivity of the method was not improved in awake animals. This strategy may be useful to investigate de desensitization of mu-OR associated with opioid tolerance in vivo.

Interactions between the Nociceptin and Toll-like Receptor Systems

Nociceptin and the nociceptin receptor (NOP) have been described as targets for treatment of pain and inflammation, whereas toll-like receptors (TLRs) play key roles in inflammation and impact opioid receptors and endogenous opioids expression. In this study, interactions between the nociceptin and TLR systems were investigated. Human THP-1 cells were cultured with or without phorbol myristate acetate (PMA 5 ng/mL), agonists specific for TLR2 (lipoteichoic acid, LTA 10 µg/mL), TLR4 (lipopolysaccharide, LPS 100 ng/mL), TLR7 (imiquimod, IMQ 10 µg/mL), TLR9 (oligonucleotide (ODN) 2216 1 µM), PMA+TLR agonists, or nociceptin (0.01−100 nM). Prepronociceptin (ppNOC), NOP, and TLR mRNAs were quantified by RT-qPCR. Proteins were measured using flow cytometry. PMA upregulated ppNOC mRNA, intracellular nociceptin, and cell membrane NOP proteins (all p < 0.05). LTA and LPS prevented PMA’s upregulating effects on ppNOC mRNA and nociceptin protein (both p < 0.05). IMQ and ODN 2216 attenuated PMA’s effects on ppNOC mRNA. PMA, LPS, IMQ, and ODN 2216 increased NOP protein levels (all p < 0.05). PMA+TLR agonists had no effects on NOP compared to PMA controls. Nociceptin dose-dependently suppressed TLR2, TLR4, TLR7, and TLR9 proteins (all p < 0.01). Antagonistic effects observed between the nociceptin and TLR systems suggest that the nociceptin system plays an anti-inflammatory role in monocytes under inflammatory conditions.

Suboxone: History, controversy, and open questions

There are more than 200 opioid overdose deaths each day in the US. In combating this epidemic we look to available treatment tools. Here, we find only three medications approved by the Food and Drug Administration (FDA) for the treatment of opioid use disorder. Of the three, buprenorphine is of particular importance due to its reduced overdose potential as a partial opioid agonist. Evidence supports its clinical equivalence to its full agonist cousin methadone, and suggests that it is better slated for long-term treatment of opioid use disorder compared to the non-selective opioid antagonist naltrexone. Buprenorphine is most popularized within Suboxone, a medication which also contains the non-selective opioid antagonist naloxone. The naloxone has no additional effect when the drug is taken as instructed, as it is intended to prevent diversion in those that would attempt to inject the medication. While Suboxone is regarded by some as the future of medical treatment, others have expressed concerns. This review aims to explore the history, controversy, and open questions that surround buprenorphine and its most prescribed variation, Suboxone. These include its pharmacological, legislative, and social history, alternative indications, efficacy as a treatment of opioid use disorder, and more. Armed with this information, the reader will have a more in-depth and holistic understanding of the medication's place in their community.

An Italian Expert Consensus on the Use of Opioids for the Management of Chronic Non-Oncological Pain in Clinical Practice: Focus on Buprenorphine

Purpose

The aim of the present work was to evaluate the knowledge and prescriptive habits of clinicians involved in the management of chronic non cancer pain (CNCP), with a special focus on the use of opioids.

Methods

A Delphi method was used. A Board of specialists elaborated and discussed a series of statements, based on available literature and personal clinical expertise, about particularly controversial topics on pain pathophysiology and treatment. A Panel of experts in the field of pain management, selected by the Board, was invited to vote the proposed statements, indicating the level of agreement on a 5-point Likert scale (1: strongly disagree; 2: disagree; 3: partially agree; 4: agree; 5: strongly agree). The threshold for consensus was set at minimum 66.6% of the number of respondents with a level of agreement ≥4 (Agree or Strongly agree).

Results

The Board included 5 pain therapists, 1 pharmacologist and 1 methodology expert and drew up a total of 36 statements (for a total of 40 requested answers)”. A total of 100 clinicians were included in the Expert Panel. Respondents were 89 (89%). Consensus was achieved for 32 out of 40 answers. Most of the lack of consensus was recorded for statements regarding opioids use, and resulted from a low level of agreement (3 on the Likert scale), suggesting a neutral position deriving from a lack of knowledge rather than a strong contrary opinion.

Conclusion

Most of the proposed items reached consensus, suggesting a generally homogeneous approach to CNCP management. However, the lack of consensus recorded for several items regarding opioid use confirms the need to fill important gaps in the knowledge of available agents. A clear explanation of the peculiar pharmacological properties of drugs associated with potential clinical advantages (such as buprenorphine) will help optimize pain treatment in both primary care and hospital settings and improving pain control in CNCP patients.