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Cell Nov 2022Morphine and fentanyl are among the most used opioid drugs that confer analgesia and unwanted side effects through both G protein and arrestin signaling pathways of...
Morphine and fentanyl are among the most used opioid drugs that confer analgesia and unwanted side effects through both G protein and arrestin signaling pathways of μ-opioid receptor (μOR). Here, we report structures of the human μOR-G protein complexes bound to morphine and fentanyl, which uncover key differences in how they bind the receptor. We also report structures of μOR bound to TRV130, PZM21, and SR17018, which reveal preferential interactions of these agonists with TM3 side of the ligand-binding pocket rather than TM6/7 side. In contrast, morphine and fentanyl form dual interactions with both TM3 and TM6/7 regions. Mutations at the TM6/7 interface abolish arrestin recruitment of μOR promoted by morphine and fentanyl. Ligands designed to reduce TM6/7 interactions display preferential G protein signaling. Our results provide crucial insights into fentanyl recognition and signaling of μOR, which may facilitate rational design of next-generation analgesics.
Topics: Humans; Analgesics, Opioid; Arrestin; Fentanyl; GTP-Binding Proteins; Morphine; Receptors, Opioid, mu
PubMed: 36368306
DOI: 10.1016/j.cell.2022.09.041 -
Pharmacogenomics Apr 2021Oxycodone is a semisynthetic μ- and κ-opioid receptor with agonist with a broad scope of use including postoperative analgesia as well as control of neuropathic and... (Review)
Review
Oxycodone is a semisynthetic μ- and κ-opioid receptor with agonist with a broad scope of use including postoperative analgesia as well as control of neuropathic and cancer pain. Advantages over other opioids include prolonged duration of action, greater potency than morphine and lack of histamine release or ceiling effect. Individual responses to oxycodone can vary due to genetic differences. This review article aims to summarize the oxycodone literature and provide context on its pharmacogenomics and pharmacokinetics. The evidence for clinical effect of genetic polymorphisms on oxycodone is conflicting. There is stronger evidence linking polymorphic genetic enzymes CYP2D6 and CYP3A with therapeutic outcomes. Further, research is needed to discern all of oxycodone's metabolites and their contribution to the overall analgesic effect.
Topics: Analgesics, Opioid; Cytochrome P-450 CYP2D6; Cytochrome P-450 CYP3A; Humans; Morphine; Oxycodone; Pharmacogenetics; Polymorphism, Genetic
PubMed: 33728947
DOI: 10.2217/pgs-2020-0143 -
Neuropharmacology Jun 2019Opioid drugs are important tools to alleviate pain of different origins, but they have strong addictive potential and their abuse at higher doses often results in... (Review)
Review
Opioid drugs are important tools to alleviate pain of different origins, but they have strong addictive potential and their abuse at higher doses often results in serious health complications. Respiratory depression that leads to brain hypoxia is perhaps the most dangerous symptom of acute intoxication with opioids, and it could result in lethality. The development of substrate-specific sensors coupled with amperometry made it possible to directly evaluate physiological and drug-induced fluctuations in brain oxygen levels in awake, freely-moving rats. The goal of this review paper is to consider changes in brain oxygen levels induced by several opioid drugs (heroin, fentanyl, oxycodone, morphine). While some of these drugs are widely used in clinical practice, they all are abused, often at doses exceeding the clinical range and often resulting in serious health complications. First, we consider some basic knowledge regarding brain oxygen, its physiological fluctuations, and mechanisms involved in regulating its entry into brain tissue. Then, we present and discuss data on brain oxygen changes induced by each opioid drug within a wide range of doses, from low, behaviorally relevant, to high, likely to be self-administered by drug users. These data allowed us to compare the effects of these drugs on brain oxygen in terms of their potency, time-course, and their potential danger when used at high doses via rapid-onset administration routes. While most data discussed in this work were obtained in rats, we believe that these data have clear human relevance in addressing the alarming rise in lethality associated with the opioid abuse.
Topics: Analgesics, Opioid; Animals; Brain; Fentanyl; Heroin; Humans; Hypoxia, Brain; Morphine; Oxycodone; Rats; Respiratory Insufficiency
PubMed: 30735692
DOI: 10.1016/j.neuropharm.2019.02.008 -
JAMA Nov 2022Chronic breathlessness is common in people with chronic obstructive pulmonary disease (COPD). Regular, low-dose, extended-release morphine may relieve breathlessness,... (Randomized Controlled Trial)
Randomized Controlled Trial
IMPORTANCE
Chronic breathlessness is common in people with chronic obstructive pulmonary disease (COPD). Regular, low-dose, extended-release morphine may relieve breathlessness, but evidence about its efficacy and dosing is needed.
OBJECTIVE
To determine the effect of different doses of extended-release morphine on worst breathlessness in people with COPD after 1 week of treatment.
DESIGN, SETTING, AND PARTICIPANTS
Multicenter, double-blind, placebo-controlled randomized clinical trial including people with COPD and chronic breathlessness (defined as a modified Medical Research Council score of 3 to 4) conducted at 20 centers in Australia. People were enrolled between September 1, 2016, and November 20, 2019, and followed up through December 26, 2019.
INTERVENTIONS
People were randomized 1:1:1 to 8 mg/d or 16 mg/d of oral extended-release morphine or placebo during week 1. At the start of weeks 2 and 3, people were randomized 1:1 to 8 mg/d of extended-release morphine, which was added to the prior week's dose, or placebo.
MAIN OUTCOMES AND MEASURES
The primary outcome was change in the intensity of worst breathlessness on a numerical rating scale (score range, 0 [none] to 10 [being worst or most intense]) using the mean score at baseline (from days -3 to -1) to the mean score after week 1 of treatment (from days 5 to 7) in the 8 mg/d and 16 mg/d of extended-release morphine groups vs the placebo group. Secondary outcomes included change in daily step count measured using an actigraphy device from baseline (day -1) to the mean step count from week 3 (from days 19 to 21).
RESULTS
Among the 160 people randomized, 156 were included in the primary analyses (median age, 72 years [IQR, 67 to 78 years]; 48% were women) and 138 (88%) completed treatment at week 1 (48 in the 8 mg/d of morphine group, 43 in the 16 mg/d of morphine group, and 47 in the placebo group). The change in the intensity of worst breathlessness at week 1 was not significantly different between the 8 mg/d of morphine group and the placebo group (mean difference, -0.3 [95% CI, -0.9 to 0.4]) or between the 16 mg/d of morphine group and the placebo group (mean difference, -0.3 [95%, CI, -1.0 to 0.4]). At week 3, the secondary outcome of change in mean daily step count was not significantly different between the 8 mg/d of morphine group and the placebo group (mean difference, -1453 [95% CI, -3310 to 405]), between the 16 mg/d of morphine group and the placebo group (mean difference, -1312 [95% CI, -3220 to 596]), between the 24 mg/d of morphine group and the placebo group (mean difference, -692 [95% CI, -2553 to 1170]), or between the 32 mg/d of morphine group and the placebo group (mean difference, -1924 [95% CI, -47 699 to 921]).
CONCLUSIONS AND RELEVANCE
Among people with COPD and severe chronic breathlessness, daily low-dose, extended-release morphine did not significantly reduce the intensity of worst breathlessness after 1 week of treatment. These findings do not support the use of these doses of extended-release morphine to relieve breathlessness.
TRIAL REGISTRATION
ClinicalTrials.gov Identifier: NCT02720822.
Topics: Aged; Female; Humans; Male; Delayed-Action Preparations; Double-Blind Method; Dyspnea; Morphine; Pulmonary Disease, Chronic Obstructive; Respiratory System Agents; Chronic Disease; Treatment Outcome
PubMed: 36413230
DOI: 10.1001/jama.2022.20206 -
Anesthesiology Jun 2020Intrathecal opioids are routinely administered during spinal anesthesia for postcesarean analgesia. The effectiveness of intrathecal morphine for postcesarean analgesia... (Comparative Study)
Comparative Study Randomized Controlled Trial
BACKGROUND
Intrathecal opioids are routinely administered during spinal anesthesia for postcesarean analgesia. The effectiveness of intrathecal morphine for postcesarean analgesia is well established, and the use of intrathecal hydromorphone is growing. No prospective studies have compared the effectiveness of equipotent doses of intrathecal morphine versus intrathecal hydromorphone as part of a multimodal analgesic regimen for postcesarean analgesia. The authors hypothesized that intrathecal morphine would result in superior analgesia compared with intrathecal hydromorphone 24 h after delivery.
METHODS
In this single-center, double-blinded, randomized trial, 138 parturients undergoing scheduled cesarean delivery were randomized to receive 150 µg of intrathecal morphine or 75 µg of intrathecal hydromorphone as part of a primary spinal anesthetic and multimodal analgesic regimen; 134 parturients were included in the analysis. The primary outcome was the numerical rating scale score for pain with movement 24 h after delivery. Static and dynamic pain scores, nausea, pruritus, degree of sedation, and patient satisfaction were assessed every 6 h for 36 h postpartum. Total opioid consumption was recorded.
RESULTS
There was no significant difference in pain scores with movement at 24 h (intrathecal hydromorphone median [25th, 75th] 4 [3, 5] and intrathecal morphine 3 [2, 4.5]) or at any time point (estimated difference, 0.5; 95% CI, 0 to 1; P = 0.139). Opioid received in the first 24 h did not differ between groups (median [25th, 75th] oral morphine milligram equivalents for intrathecal hydromorphone 30 [7.5, 45.06] vs. intrathecal morphine 22.5 [14.0, 37.5], P = 0.769). From Kaplan-Meier analysis, the median time to first opioid request was 5.4 h for hydromorphone and 12.1 h for morphine (log-rank test P = 0.200).
CONCLUSIONS
Although the hypothesis was that intrathecal morphine would provide superior analgesia to intrathecal hydromorphone, the results did not confirm this. At the doses studied, both intrathecal morphine and intrathecal hydromorphone provide effective postcesarean analgesia when combined with a multimodal analgesia regimen.
Topics: Adult; Analgesia, Epidural; Analgesia, Obstetrical; Analgesics, Opioid; Cesarean Section; Double-Blind Method; Female; Humans; Hydromorphone; Male; Morphine; Pain, Postoperative; Treatment Outcome
PubMed: 32251031
DOI: 10.1097/ALN.0000000000003283 -
JAMA Pediatrics Aug 2018Although opioids are used to treat neonatal abstinence syndrome (NAS), the best pharmacologic treatment has not been established. (Comparative Study)
Comparative Study Randomized Controlled Trial
IMPORTANCE
Although opioids are used to treat neonatal abstinence syndrome (NAS), the best pharmacologic treatment has not been established.
OBJECTIVE
To compare the safety and efficacy of methadone and morphine in NAS.
DESIGN, SETTING, AND PARTICIPANTS
In this randomized, double-blind, intention-to-treat trial, term infants from 8 US newborn units whose mothers received buprenorphine, methadone, or opioids for pain control during pregnancy were eligible. A total of 117 infants were randomized to receive methadone or morphine from February 9, 2014, to March 6, 2017. Mothers who declined randomization could consent to data collection and standard institutional treatment.
INTERVENTIONS
Infants were assessed with the Finnegan Neonatal Abstinence Scoring System every 4 hours and treated with methadone or placebo every 4 hours or morphine every 4 hours. Infants with persistently elevated Finnegan scores received dose increases. Infants who exceeded a predetermined opioid dose received phenobarbital. Dose reductions occurred every 12 to 48 hours when signs of NAS were controlled with therapy, stopping at 20% of the original dose.
MAIN OUTCOMES AND MEASURES
The primary end point was length of hospital stay (LOS). The secondary end points were LOS attributable to NAS and length of drug treatment (LOT).
RESULTS
A total of 183 mothers consented to have their infants in the study; 117 infants required treatment. Because 1 parent withdrew consent, data were analyzed on 116 infants (mean [SD] gestational age, 39.1 [1.1] weeks; mean [SD] birth weight, 3157 [486] g; 58 [50%] male). Demographic variables and risk factors were similar except for more prenatal cigarette exposure in infants who received methadone. Adjusting for study site and maternal opioid type, methadone was associated with decreased mean number of days for LOS by 14% (relative number of days, 0.86; 95% CI, 0.74-1.00; P = .046), corresponding to a difference of 2.9 days; 14% reduction in LOS attributable to NAS (relative number of days, 0.86; 95% CI, 0.77-0.96; P = .01), corresponding to a difference of 2.7 days; and 16% reduction in LOT (relative number of days, 0.84; 95% CI, 0.73-0.97; P = .02), corresponding to a difference of 2.3 days. Methadone was also associated with reduced median LOS (16 vs 20 days, P = .005), LOS attributable to NAS (16 vs 19 days, P = .005), and LOT (11.5 vs 15 days, P = .009). Study infants had better short-term outcomes than 170 nonrandomized infants treated with morphine per standard institutional protocols.
CONCLUSIONS AND RELEVANCE
With use of weight- and sign-based treatment for NAS, short-term outcomes were better in infants receiving methadone compared with morphine. Assessment of longer-term outcomes is ongoing.
TRIAL REGISTRATION
ClinicalTrials.gov Identifier: NCT01958476.
Topics: Analgesics, Opioid; Double-Blind Method; Female; Humans; Infant, Newborn; Intention to Treat Analysis; Male; Methadone; Morphine; Neonatal Abstinence Syndrome; Treatment Outcome
PubMed: 29913015
DOI: 10.1001/jamapediatrics.2018.1307 -
Clinics (Sao Paulo, Brazil) Aug 2016Morphine is an agonist of the µ and k receptors, whose activation results in analgesia. Morphine-like agonists act through the µ opioid receptors to cause pain relief,... (Review)
Review
Morphine is an agonist of the µ and k receptors, whose activation results in analgesia. Morphine-like agonists act through the µ opioid receptors to cause pain relief, sedation, euphoria and respiratory depression. Morphine is glucuronidated and sulfated at positions 3 and 6; the plasma concentration ratios correlate positively with birth weight, which probably reflects increased liver weight with increasing birth weight. Moreover, morphine clearance correlates positively with gestational age and birth weight. Steady-state morphine plasma concentrations are achieved after 24-48 hours of infusion, but the glucuronide metabolite plasma concentrations do not reach steady state before 60 hours. The morphine-3-glucuronide metabolite has lower clearance, a shorter half-life and a smaller distribution volume compared with the morphine-6 metabolite, which is the most active morphine-like agonist. Ordinary doses cause constipation, urinary retention and respiratory depression. Neonatal pain relief may require a blood level of approximately 120 ng/ml, whereas lower levels (20-40 ng/ml) seem adequate for children. A bibliographic search was performed using the PubMed database and the keywords "morphine metabolism neonate" and "morphine pharmacokinetics neonate". The initial and final cutoff points were January 1990 and September 2015, respectively. The results indicate that morphine is extensively glucuronidated and sulfated at positions 3 and 6, and that the glucuronidation rate is lower in younger neonates compared with older infants. Although much is known about morphine in neonates, further research will be required to ensure that recommended therapeutic doses for analgesia in neonates are evidence based.
Topics: Age Factors; Analgesics, Opioid; Birth Weight; Central Nervous System Stimulants; Extracorporeal Membrane Oxygenation; Gestational Age; Humans; Infant, Newborn; Morphine; Morphine Derivatives; Respiration, Artificial; Time Factors
PubMed: 27626479
DOI: 10.6061/clinics/2016(08)11 -
Science Advances Jun 2023The association between rewarding and drug-related memory is a leading factor for the formation of addiction, yet the neural circuits underlying the association remain...
The association between rewarding and drug-related memory is a leading factor for the formation of addiction, yet the neural circuits underlying the association remain unclear. Here, we showed that the interstitial nucleus of the posterior limb of the anterior commissure (IPAC) integrated rewarding and environmental memory information by two different receiving projections from ventral tegmental area (VTA) and nucleus accumbens shell region (NAcSh) to mediate the acquisition of morphine conditioned place preference (CPP). A projection from the VTA GABAergic neurons (VTA) to the IPAC lateral region GABAergic neurons (IPACL) mediated the effect of morphine rewarding, whereas the pathway from NAcSh dopamine receptor 1-expressing neurons (NAcSh) to the IPAC medial region GABAergic neurons (IPACM) was involved in the acquisition of environmental memory. These findings demonstrated that the distinct IPAC circuits VTAIPACL and NAcShIPACM were attributable to the rewarding and environmental memory during the acquisition of morphine CPP, respectively, and provided the circuit-based potential targets for preventing and treating opioid addiction.
Topics: Morphine; Ventral Tegmental Area; Reward; GABAergic Neurons; gamma-Aminobutyric Acid
PubMed: 37352353
DOI: 10.1126/sciadv.adg5849 -
Molecules (Basel, Switzerland) Apr 20226,14-ethenomorphinans are semisynthetic opiate derivatives containing an ethylene bridge between positions 6 and 14 in ring-C of the morphine skeleton that imparts a... (Review)
Review
6,14-ethenomorphinans are semisynthetic opiate derivatives containing an ethylene bridge between positions 6 and 14 in ring-C of the morphine skeleton that imparts a rigid molecular structure. These compounds represent an important family of opioid receptor ligands in which the 6,14-etheno bridged structural motif originates from a [4 + 2] cycloaddition of morphinan-6,8-dienes with dienophiles. Certain 6,14-ethenomorphinans having extremely high affinity for opioid receptors are often non-selective for opioid receptor subtypes, but this view is now undergoing some revision. The agonist 20-etorphine and 20-dihydroetorphine are several thousand times more potent analgesics than morphine, whereas diprenorphine is a high-affinity non-selective antagonist. The partial agonist buprenorphine is used as an analgesic in the management of post-operative pain or in substitution therapy for opiate addiction, sometimes in combination with the non-selective antagonist naloxone. In the context of the current opioid crisis, we communicated a summary of several decades of work toward generating opioid analgesics with lesser side effects or abuse potential. Our summary placed a focus on Diels-Alder reactions of morphinan-6,8-dienes and subsequent transformations of the cycloadducts. We also summarized the pharmacological aspects of radiolabeled 6,14-ethenomorphinans used in molecular imaging of opioid receptors.
Topics: Analgesics; Analgesics, Opioid; Morphinans; Morphine; Naloxone; Receptors, Opioid; Receptors, Opioid, mu
PubMed: 35566212
DOI: 10.3390/molecules27092863 -
Acta Medica Portuguesa Mar 2016
Topics: Analgesics, Opioid; Humans; Morphine; Practice Guidelines as Topic
PubMed: 27285090
DOI: 10.20344/amp.7663