Oliceridine: A Novel Drug for the Management of Moderate to Severe Acute Pain - A Review of Current Evidence

A free-radical design featuring an intramolecular migration for a synthetically versatile alkyl-(hetero)arylation of simple olefins

A free-radical approach has enabled the development of a synthetically versatile alkyl-(hetero)arylation of olefins. Alkyl and (hetero)aryl groups were added concurrently to a full suite of mono- to tetrasubstituted simple alkenes (i.e., without requiring directing or electronically activating groups) for the first time. Key advances also included the introduction of synthetically diversifiable alkyl groups featuring different degrees of substitution, good diastereocontrol in both cyclic and acyclic settings, the addition of biologically valuable heteroarenes featuring Lewis basic nitrogen atoms as well as simple benzenes, and the generation of either tertiary or quaternary benzylic centers. The synthetic potential of this transformation was demonstrated by leveraging it as the key step in a concise synthesis of oliceridine, a new painkiller that received FDA approval in 2020.

Subacute toxicity evaluations of LPM3480392 in rats, a full µ-opioid receptor biased agonist

Opiates produce analgesia via G-protein signaling, and adverse effects, such as respiratory depression and decreased bowel motility, by β-arrestin pathway. Oliceridine, a G protein-biased MOR agonist, only presents modest safety advantages as compared to other opiates in clinical trials, possibly due to its limited bias. Our previous study shown that LPM3480392, a full MOR biased agonist, is selective for the Gi pathway over the β-arrestin-2. In the present article, we evaluated the subacute toxicity of LPM3480392 in rats. The rats were administered with control article or LPM3480392 0.6, 1.2 or 2.4 mg/kg/day for 4 consecutive weeks followed by a 4-week recovery phase. Intravenous infusion was conducted at tail vein at 0.2, 0.4 or 0.8 mg/kg/day with a dosing volume of 10 mL/kg and 5 min/rat/dose, three times a day with an interval of approximately 4 h. The concomitant toxicokinetics study was conducted. Two unscheduled rats at 2.4 mg/kg/day died with no clear cause. For the scheduled necropsy, the major effects were associated with the MOR agonist-related pharmacodynamic properties of LPM3480392 (e.g., increased activity, increased muscle tone; decreased food consumption and body weight gain; and clinical chemistry changes related with decreased food consumption) in three LPM3480392 groups. In addition, LPM3480392 at 2.4 mg/kg/day also induced deep respiration and histopathology changes in testis and epididymis in sporadic individual rats. However, different from other opiates, LPM3480392 presents weak/no immunosuppression and the decreased adrenal gland weight, which may be due to LPM3480392' full MOR bias. At the end of recovery phase, all findings were recovered to some extent or completely. In the toxicokinetics study, the dose-dependent elevation of drug exposure was observed, which partly explained the toxicity of high dose. In summary, LPM3480392 has exhibited good safety characteristics in this subacute toxicity study in rats.

Opioids-Induced Inhibition of HERG Ion Channels and Sudden Cardiac Death, A Systematic Review of Current Literature

BACKGROUND

It is estimated that over 60 million individuals regularly use opioids globally, with opioid use disorder increasing substantially in the past decade. Several reports have linked sudden cardiac death, QTc prolongation, and other adverse cardiovascular outcomes with opioid use through their inhibitory effect on the human ether-a-go-go-related gene (HERG) ion channel. Therefore, understanding this underlying mechanism may be critical for risk prevention and management in prescribing opioids and treating patients with opioid dependency.

AIM

The present systematic review summarizes the current literature on the impact of opioids-induced inhibition of HERG channel function and its relationship with sudden cardiac death, QTc prolongation, and other cardiovascular adverse effects.

METHODS

A systematic review was conducted of the databases PubMed, EMBASE, Cochrane, and ClinicalTrials.gov of primary studies that reported the effects of opioids on HERG channel function and associated cardiovascular outcomes.

RESULTS

The search identified 1,546 studies, of which 12 were finally included for data extraction. Based on the current literature, methadone, oliceridine, l-α-acetylmethadol (LAAM), and fentanyl were found to inhibit the HERG channel function and were associated with QTc prolongation. However, other opioids such as morphine, codeine, tramadol, and buprenorphine were not associated with inhibition of HERG channels or QTc prolongation. Additional cardiac outcomes associated with opioid related HERG channels dysfunction included sudden cardiac death and torsade de pointes.

CONCLUSION

Our findings suggest that certain opioid consumption may result in the inhibition of HERG channels, subsequently prolonging the QTc interval and increasing patient susceptibility to sudden cardiac death.

Emerging principles of cytokine pharmacology and therapeutics

Cytokines are secreted signalling proteins that play essential roles in the initiation, maintenance and resolution of immune responses. Although the unique ability of cytokines to control immune function has garnered clinical interest in the context of cancer, autoimmunity and infectious disease, the use of cytokine-based therapeutics has been limited. This is due, in part, to the ability of cytokines to act on many cell types and impact diverse biological functions, resulting in dose-limiting toxicity or lack of efficacy. Recent studies combining structural biology, protein engineering and receptor pharmacology have unlocked new insights into the mechanisms of cytokine receptor activation, demonstrating that many aspects of cytokine function are highly tunable. Here, we discuss the pharmacological principles underlying these efforts to overcome cytokine pleiotropy and enhance the therapeutic potential of this important class of signalling molecules.

Oliceridine for the Management of Moderate to Severe Acute Postoperative Pain: A Narrative Review

Despite current advances in acute postoperative pain management, prevalence remains high. Inadequate treatment could lead to poor outcomes and even progression to chronic pain. Opioids have traditionally been the mainstay for treatment of moderate to severe acute pain. However, their use has been associated with opioid-related adverse events (ORAEs), such as respiratory depression, sedation, nausea, vomiting, pruritus, and decreased bowel motility. In addition, their liberal use has been implicated in the current opioid epidemic. As a result, there has been renewed interest in multimodal analgesia to target different mechanisms of action in order to achieve a synergistic effect and minimize opioid usage. Oliceridine is a novel mu-opioid receptor agonist that is part of a new class of biased ligands that selectively activate G-protein signaling and downregulate β-arrestin recruitment. Since G-protein signaling has been associated with analgesia while β-arrestin recruitment has been associated with ORAEs, there is potential for a wider therapeutic window. In this review, we will discuss the clinical evidence behind oliceridine and its potential role in acute postoperative pain management. We have systematically searched the PubMed database using the keywords oliceridine, olinvyk, and trv130. All articles identified were reviewed and evaluated, and all clinical trials were included.

Design and Synthesis of Fsp3-Enriched Spirocyclic-Based Biological Screening Compound Arrays via DOS Strategies and Their NNMT Inhibition Profiling

Medicinal chemists are keen to explore tridimensional compounds, especially when it comes to small molecules. It has already been stressed that the majority of known drugs tend to be flat, whereas natural products tend to be more tridimensional and represent a good source of active compounds. 3D metrics have been implemented and computational descriptors are available to evaluate and prioritize compounds based on their 3D geometry. This is usually done by comparing the saturated carbon atoms in a molecule with the total number of its non-hydrogen atoms (the Fsp3 value). While this aspect is clear, still there are not enough synthetic tools that support the realization of novel chemotypes that conform to these criteria. Herein we describe a diversity oriented synthesis (DOS) synthetic cascade technology that starts from two simple reagents, and generates highly enriched Fsp3 novel and diverse spiro-scaffolds with pragmatic synthetic handles (points of diversity). The spiro nature of these scaffolds not only ensures high Fsp3 values but renders the compounds more rigid and therefore more effective in forming precise stereo-interactions with their potential biological targets. These compounds were also profiled for their drug-like properties and as potential modulators of the NNMT enzyme.

Signaling underlying kappa opioid receptor-mediated behaviors in rodents

Kappa opioid receptor (KOR) agonists are potentially useful as analgesic and anti-pruritic agents, for prevention and treatment of substance use disorders, and for treatment of demyelinating diseases. However, side effects of KOR agonists, including psychotomimesis, dysphoria, and sedation, have caused early termination of clinical trials. Understanding the signaling mechanisms underlying the beneficial therapeutic effects and the adverse side effects may help in the development of KOR agonist compounds. In this review, we summarize the current knowledge in this regard in five sections. First, studies conducted on mutant mouse lines (GRK3-/-, p38alpha MAPK-/-, β-arrestin2-/-, phosphorylation-deficient KOR) are summarized. In addition, the abilities of four distinct KOR agonists, which have analgesic and anti-pruritic effects with different side effect profiles, to cause KOR phosphorylation are discussed. Second, investigations on the KOR agonist nalfurafine, both in vitro and in vivo are reviewed. Nalfurafine was the first KOR full agonist approved for clinical use and in the therapeutic dose range it did not produce significant side effects associated with typical KOR agonists. Third, large-scale high-throughput phosphoproteomic studies without a priori hypotheses are described. These studies have revealed that KOR-mediated side effects are associated with many signaling pathways. Fourth, several novel G protein-biased KOR agonists that have been characterized for in vitro biochemical properties and agonist biases and in vivo behavior effects are described. Lastly, possible mechanisms underlying KOR-mediated CPA, hypolocomotion and motor incoordination are discussed. Overall, it is agreed upon that the analgesic and anti-pruritic effects of KOR agonists are mediated via G protein signaling. However, there is no consensus on the mechanisms underlying their side effects. GRK3, p38 MAPK, β-arrestin2, mTOR pathway, CB1 cannabinoid receptor and protein kinase C have been implicated in one side effect or another. For drug discovery, after initial in vitro characterization, in vivo pharmacological characterizations in various behavior tests are still the most crucial steps and dose separation between beneficial therapeutic effects and adverse side effects are the critical determinant for the compounds to be moved forward for clinical development.

Multimodal Pain Management in Orthopedic Surgery

Background: Orthopedic surgery typically results in moderate to severe pain in a majority of patients. Opioids were traditionally the primary medication to target mechanisms of pain transmission. Multimodal analgesia has become a preferred method of pain management in orthopedic practice. Utilizing more than one mode to address post-surgical pain by recruiting multiple receptors through different medications accelerates the recovery process and decreases the need for opioids. By implementing effective analgesic techniques and interventions, this practice, in turn, decreases the usage of perioperative opioids, and in the long term, prevents addiction to pain medications and risk of opioid overdose. In orthopedic surgeries, previous studies have found that multimodal analgesia has reduced early opioid usage in the postoperative course. Pain is the result of direct injury to the nervous system, with a wide variety of chemicals directly stimulating or sensitizing the peripheral nociceptors. The pathophysiology behind the mechanism of post-surgical pain, along with the importance of preoperative, perioperative, and postoperative pain regimens are emphasized. A brief overview of pain medications and their properties is provided. These medications are further categorized, with information on special considerations and typical dosage requirements. Pain management should address both neuropathic and subjective types of pain. Effective pain control requires constant reassessment with individualized strategies. Conclusion: By focusing on multimodal analgesia, anesthesiologists can now utilize newer techniques for postoperative pain relief from orthopedic surgery, with better short-term and long-term outcomes for the patient.

Discovery of pyrazole-1-carboxamide derivatives as novel Gi-biased μ-opioid receptor agonists

μ-Opioid receptor (MOR) Gi-biased agonists with no recruitment of β-arrestin were introduced as a new analgesic strategy to overcome the conventional undesirable side effects of opioid receptor-targeted drugs, such as tolerance, addiction, respiratory depression, and constipation. For the development of novel Gi-biased MOR agonists, the design, synthesis, and structure-activity relationship (SAR) analysis of the aminopyrazole core skeleton were conducted according to the current SAR data of PZM21 (2a) and its derivatives. New derivatives were biologically evaluated for their agonistic effects on cyclic adenosine monophosphate (cAMP) levels for the Gi pathway and β-arrestin recruitment in MOR/κ-opioid receptor/δ opioid receptor. An optimized selective Gi-biased agonist, Compound 17a, was discovered with potent cAMP inhibitory activities, with a 50% efficacy concentration value of 87.1 nM and no activity in the MOR β-arrestin pathway and other subtypes. The in vivo pain relief efficacy of Compound 17a was confirmed in a dose-dependent manner with spinal nerve ligation and cisplatin-induced peripheral neuropathy rodent neuropathic pain models.

Opioid epidemic: lessons learned and updated recommendations for misuse involving prescription versus non-prescription opioids

INTRODUCTION

In the past decades, the opioid crisis has heavily impacted parts of the US society and has been followed by an increase in the use of opioids worldwide. It is of paramount importance that we explore the origins of the US opioid epidemic to develop best practices to tackle the rising tide of opioid overdoses.

AREAS COVERED

In this expert review, we discuss opioid (over)prescription, change in perception of pain, and false advertisement of opioid safety as the leading causes of the US opioid epidemic. Then, we review the evidence about opioid dependence and addiction potential and provide current knowledge about predictors of aberrant opioid-related behavior. Lastly, we discuss different approaches that were considered or undertaken to combat the rising tide of opioid-related deaths by regulatory bodies, pharmaceutical companies, and health-care professionals. For this expert review, we considered published articles relevant to the topic under investigation that we retrieved from Medline or Google scholar electronic database.

EXPERT OPINION

The opioid epidemic is a dynamic process with many underlying mechanisms. Therefore, no single approach may be best suited to combat it. In our opinion, the best way forward is to employ multiple strategies to tackle different underlying mechanisms.

Tyrosine 7.43 is important for mu-opioid receptor downstream signaling pathways activated by fentanyl

G protein–coupled receptors can signal through both G proteins and ß-arrestin2. For the µ-opioid receptor (MOR), early experimental evidence from a single study suggested that G protein signaling mediates analgesia and sedation, whereas ß-arrestin signaling mediates respiratory depression and constipation. Then, receptor mutations were used to clarify which residues interact with ligands to selectively regulate signals in a ligand-specific manner. However, there is no systematic study on how to determine these residues and clarify the molecular mechanism of their influence on signal pathways. We have therefore used molecular docking to predict the amino acid sites that affect the binding of ligands and MOR. Then, the corresponding sites were mutated to determine the effect of the structural determinant of MOR on G_i/o protein and ß-arrestin pathways. The pharmacological and animal behavioral experiments in combination with molecular dynamics simulations were used to elucidate the molecular mechanism of key residues governing the signaling. Without affecting ligand binding to MOR, MOR^Y7.43A attenuated the activation of both G_i/o protein and ß-arrestin signaling pathways stimulated by fentanyl, whereas it did not change these two pathways stimulated by morphine. Likewise, the activation peak time of extracellular regulated protein kinases was significantly prolonged at MOR^Y7.43A compared with that at MOR^wildtype stimulated by fentanyl, but there was no difference stimulated by morphine. In addition, MOR^Y7.43A significantly enhanced analgesia by fentanyl but not by morphine in the mice behavioral experiment. Furthermore, the molecular dynamics simulations showed that H6 moves toward the cellular membrane. H6 of the fentanyl–Y7.43A system moved outward more than that in the morphine–Y7.43A system. Y7.43 mutation disrupted hydrophobic interactions between W6.48 and Y7.43 in the fentanyl–Y7.43A system but not in the morphine–Y7.43A system. Our results have disclosed novel mechanisms of Y7.43 mutation affecting MOR signaling pathways. Y7.43 mutation reduced the activation of the G_i/o protein pathway and blocked the ß-arrestin2 recruitment, increased the H6 outward movement of MOR, and disrupted hydrophobic interactions. This may be responsible for the enhanced fentanyl analgesia. These findings are conducive to designing new drugs from the perspective of ligand and receptor binding, and Y7.43 is also expected to be a key site to structure optimization of synthesized compounds.

Synthetic Approaches to the New Drugs Approved During 2020

New drugs introduced to the market are privileged structures that have affinities for biological targets implicated in human diseases and conditions. These new chemical entities (NCEs), particularly small molecules and antibody-drug conjugates (ADCs), provide insight into molecular recognition and simultaneously function as leads for the design of future medicines. This Review is part of a continuing series presenting the most likely process-scale synthetic approaches to 44 new chemical entities approved for the first time anywhere in the world during 2020.

Recent Progress in Assays for GPCR Drug Discovery

G-protein coupled receptors (GPCRs), also known as 7 transmembrane receptors, are the largest family of cell surface receptors in eukaryotes. There are ~800 GPCRs in human, regulating diverse physiological processes. GPCRs are the most intensively studied drug targets. Drugs that target GPCRs account for about a quarter of the global market share of therapeutic drugs. Therefore, to develop physiologically relevant and robust assays to search new GPCR ligands or modulators remain the major focus of drug discovery research worldwide. Early functional GPCR assays are mainly depend on the measurement of G protein-mediated second messenger generation. Recent development in GPCR biology indicate the signaling of these receptors is much more complex than the oversimplified classical view. GPCRs have been found to activate multiple G proteins simultaneously and induce b-arrestin-mediated signaling. GPCRs have also been found to interacte with other cytosolic scaffolding proteins and form dimer or heteromer with GPCRs or other transmembrane proteins. Here we mainly discuss technologies focused on detecting protein-protein interactions, such as FRET/BRET, NanoBiT, Tango, etc, and their applications in measuring GPCRs interacting with various signaling partners. In the final part, we also discuss the species differences in GPCRs when using animal models to study the in vivofunctions of GPCR ligands, and possible ways to solve this problem with modern genetic tools.

Oxadiazole: A highly versatile scaffold in drug discovery

As a pharmacologically important heterocycle, oxadiazole paved the way to combat the problem associated with the confluence of many commercially available drugs with different pharmacological profiles. The present review focuses on the potential applications of five-membered heterocyclic oxadiazole derivatives, especially 1,2,4-oxadiazole, 1,2,5-oxadiazole, and 1,3,4-oxadiazole, as therapeutic agents. Designing new hybrid molecules containing the oxadiazole moiety is a better solution for the development of new drug molecules. The designed molecules may accumulate a biological profile better than those of the drugs currently available on the market. The present review will guide the way for researchers in the field of medicinal chemistry to design new biologically active molecules based on the oxadiazole nucleus. Antitubercular, antimalarial, anti-inflammatory, anti-HIV, antibacterial, and anticancer activities of various oxadiazoles have been reviewed extensively here.

Discovery of a functionally selective ghrelin receptor (GHSR1a) ligand for modulating brain dopamine

The modulation of growth hormone secretagogue receptor-1a (GHSR_1a) signaling is a promising strategy for treating brain conditions of metabolism, aging, and addiction. GHSR_1a activation results in pleiotropic physiological outcomes through distinct and pharmacologically separable G protein– and β-arrestin (βarr)–dependent signaling pathways. Thus, pathway-selective modulation can enable improved pharmacotherapeutics that can promote therapeutic efficacy while mitigating side effects. Here, we describe the discovery of a brain-penetrant small molecule, N8279 (NCATS-SM8864), that biases GHSR_1a conformations toward Gα_q activation and reduces aberrant dopaminergic behavior in mice. N8279 represents a promising chemical scaffold to advance the development of better treatments for GHSR_1a-related brain disorders involving the pathological dysregulation of dopamine.

The growth hormone secretagogue receptor-1a (GHSR_1a) is the cognate G protein–coupled receptor (GPCR) for the peptide hormone ghrelin. GHSR_1a is a promising therapeutic target for a wide range of metabolic, age-related, and central nervous system (CNS)–based conditions. In addition, growing evidence supports that GHSR_1a is a modulator of dopamine (DA) homeostasis and is neuroprotective within brain DA circuits. GHSR_1a signaling originates from pharmacologically separable G protein– and β-arrestin (βarr)–dependent pathways, and consequently, GHSR_1a-mediated physiological responses depend upon their distinctive signaling contributions. Thus, when treating disorders of disrupted DA homeostasis, a pharmacological strategy that modulates biased GHSR_1a signaling may uncouple desired therapeutic outcomes from unwanted side effects. Here, we report the discovery of a small molecule GHSR_1a agonist, N8279 (NCATS-SM8864), functionally selective for G protein signaling. Comprehensive pharmacological characterization reveals that N8279 elicits potent Gα_q activity at the apo- and ghrelin-bound GHSR_1a. Further biochemical analysis and molecular modeling demonstrate that N8279 signaling requires the extracellular domain of GHSR_1a, especially extracellular loop 2. Collectively, these findings suggest that N8279 possesses an extended binding mode into the extracellular vestibule of the GHSR_1a that preferentially favors Gα_q signaling over alternative G proteins and βarr2-dependent cellular responses. Critically, N8279 is brain-penetrant in mice, exhibits CNS stability, and attenuates dysfunctional DA-mediated behaviors in both genetic and pharmacological mouse models of hyperdopaminergia. Our findings provide insight into the mechanisms governing GPCR functional selectivity and emphasize how biased ligand drug development can produce novel GHSR_1a pharmacotherapeutics to treat pathological disruptions of brain DA homeostasis.

A Dive Into Oliceridine and Its Novel Mechanism of Action

The current state of the opioid epidemic has revealed the need of utilizing proper pain management, especially in the postoperative setting where there is overuse of potent analgesics. However, the adequate treatment of pain is necessary to reduce mortality and cost of burden while increasing recovery and improving quality of life. Treatment of pain can be difficult to standardize as the guidelines from the American Pain Society discuss the importance of tailoring treatment options based on a patient’s sensitivities and risk factors. An effective fast-acting analgesic with adequate potency and few adverse events is the key to alleviating acute pain. Oliceridine (Olinvyk^®, Trevena Inc., Chesterbrook, USA) is a novel G protein-biased μ-opioid receptor agonist designed to decrease opioid-related adverse events (ORAEs) compared to conventional opioids. This article discusses oliceridine’s novel mechanism of action and current place in therapy. After a literature search on clinicaltrials.gov, three clinical trials were analyzed to understand the safety and efficacy of oliceridine. These trials demonstrated a comparable efficacy to morphine with a decreased risk for serious adverse events. However, further studies need to be conducted to evaluate the true safety impact of oliceridine compared to conventional opioids. 

Biased and allosteric modulation of bone cell-expressing G protein-coupled receptors as a novel approach to osteoporosis therapy

On the cellular level, osteoporosis (OP) is a result of imbalanced bone remodeling, in which osteoclastic bone resorption outcompetes osteoblastic bone formation. Currently available OP medications include both antiresorptive and bone-forming drugs. However, their long-term use in OP patients, mainly in postmenopausal women, is accompanied by severe side effects. Notably, the fundamental coupling between bone resorption and formation processes underlies the existence of an undesirable secondary outcome that bone anabolic or anti-resorptive drugs also reduce bone formation. This drawback requires the development of anti-OP drugs capable of selectively stimulating osteoblastogenesis and concomitantly reducing osteoclastogenesis. We propose that the application of small synthetic biased and allosteric modulators of bone cell receptors, which belong to the G-protein coupled receptors (GPCR) family, could be the key to resolving the undesired anti-OP drug selectivity. This approach is based on the capacity of these GPCR modulators, unlike the natural ligands, to trigger signaling pathways that promote beneficial effects on bone remodeling while blocking potentially deleterious effects. Under the settings of OP, an optimal anti-OP drug should provide fine-tuned regulation of downstream effects, for example, intermittent cyclic AMP (cAMP) elevation, preservation of Ca²⁺ balance, stimulation of osteoprotegerin (OPG) and estrogen production, suppression of sclerostin secretion, and/or preserved/enhanced canonical β-catenin/Wnt signaling pathway. As such, selective modulation of GPCRs involved in bone remodeling presents a promising approach in OP treatment. This review focuses on the evidence for the validity of our hypothesis.