A Phase I Placebo-Controlled Trial Comparing the Effects of Buprenorphine Buccal Film and Oral Oxycodone Hydrochloride Administration on Respiratory Drive

Oxycodone: A Current Perspective on Its Pharmacology, Abuse, and Pharmacotherapeutic Developments

Oxycodone, a semisynthetic derivative of naturally occurring thebaine, an opioid alkaloid, has been available for more than 100 years. Although thebaine cannot be used therapeutically due to the occurrence of convulsions at higher doses, it has been converted to a number of other widely used compounds that include naloxone, naltrexone, buprenorphine, and oxycodone. Despite the early identification of oxycodone, it was not until the 1990s that clinical studies began to explore its analgesic efficacy. These studies were followed by the pursuit of several preclinical studies to examine the analgesic effects and abuse liability of oxycodone in laboratory animals and the subjective effects in human volunteers. For a number of years oxycodone was at the forefront of the opioid crisis, playing a significant role in contributing to opioid misuse and abuse, with suggestions that it led to transitioning to other opioids. Several concerns were expressed as early as the 1940s that oxycodone had significant abuse potential similar to heroin and morphine. Both animal and human abuse liability studies have confirmed, and in some cases amplified, these early warnings. Despite sharing a similar structure with morphine and pharmacological actions also mediated by the μ-opioid receptor, there are several differences in the pharmacology and neurobiology of oxycodone. The data that have emerged from the many efforts to analyze the pharmacological and molecular mechanism of oxycodone have generated considerable insight into its many actions, reviewed here, which, in turn, have provided new information on opioid receptor pharmacology. SIGNIFICANCE STATEMENT: Oxycodone, a μ-opioid receptor agonist, was synthesized in 1916 and introduced into clinical use in Germany in 1917. It has been studied extensively as a therapeutic analgesic for acute and chronic neuropathic pain as an alternative to morphine. Oxycodone emerged as a drug with widespread abuse. This article brings together an integrated, detailed review of the pharmacology of oxycodone, preclinical and clinical studies of pain and abuse, and recent advances to identify potential opioid analgesics without abuse liability.

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).

Pharmacokinetics of Buprenorphine Buccal Film and Orally-administered Oxycodone in a Respiratory Study: An Analysis of Secondary Outcomes from a Randomized Controlled Trial

OBJECTIVE

To evaluate pharmacokinetic (PK) parameters and oxygen saturation as markers of abuse potential after administration of buprenorphine buccal film (BBF) and immediate-release (IR) oxycodone.

METHODS

This was a secondary analysis of data from a phase I randomized controlled trial. A total of 19 healthy subjects who self-identified as recreational opioid users were enrolled, with 15 completing the study. Subjects were administered 300, 600, and 900 µg BBF; 30 and 60 mg orally-administered oxycodone; and placebo. For PK analysis, blood samples were collected before dosing and at 0.5, 1, 2, 3, 4, and 6 h postdose. Respiratory drive/ventilatory response to hypercapnia and oxygen saturation were evaluated before dosing and up to 8 h after administration of test drugs.

RESULTS

Median time to maximum concentration (T_max) was 2.17 h for 900 µg BBF and 1.17 h for 60 mg oxycodone and was similar across all doses for each drug. Mean maximum concentration (C_max) was 1.06 ng/mL for 900 µg BBF and 132 ng/mL for 60 mg oxycodone. The abuse quotient, defined as C_max/T_max, was substantially higher for oxycodone compared to BBF. Respiratory depression (maximum decrease in minute ventilation) was similar for all 3 doses of BBF, consistent with a potential ceiling effect. In addition, respiratory depression occurred sooner with oxycodone vs BBF, and a greater mean decrease in oxygen saturation was observed for oxycodone 30- and 60-mg doses, compared with BBF.

CONCLUSION

These results indicate that BBF may have a decreased risk of abuse and respiratory depression compared with the full µ-opioid receptor agonist oxycodone.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT03996694.

Endogenous opiates and behavior: 2020

This paper is the forty-third consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2020 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

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.

Benefit-Risk Analysis of Buprenorphine for Pain Management

Health care providers in the United States are facing challenges in selecting appropriate medication for patients with acute and chronic pain in the midst of the current opioid crisis and COVID-19 pandemic. When compared with conventional opioids, the partial µ-opioid receptor agonist buprenorphine has unique pharmacologic properties that may be more desirable for pain management. The formulations of buprenorphine approved by the US Food and Drug Administration for pain management include intravenous injection, transdermal patch, and buccal film. A comparison of efficacy and safety data from studies of buprenorphine and conventional opioids suggests that buprenorphine may be a better-tolerated treatment option for many patients that provides similar or superior analgesia. Our benefit-risk assessment in this narrative review suggests that health care providers should consider that buprenorphine may be an appropriate alternative for pain management over other opioids.