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Translational Psychiatry Apr 2023Heroin is an opioid agonist commonly abused for its rewarding effects. Since its synthesis at the end of the nineteenth century, its popularity as a recreational drug... (Review)
Review
Heroin is an opioid agonist commonly abused for its rewarding effects. Since its synthesis at the end of the nineteenth century, its popularity as a recreational drug has ebbed and flowed. In the last three decades, heroin use has increased again, and yet the pharmacology of heroin is still poorly understood. After entering the body, heroin is rapidly deacetylated to 6-monoacetylmorphine (6-MAM), which is then deacetylated to morphine. Thus, drug addiction literature has long settled on the notion that heroin is little more than a pro-drug. In contrast to these former views, we will argue for a more complex interplay among heroin and its active metabolites: 6-MAM, morphine, and morphine-6-glucuronide (M6G). In particular, we propose that the complex temporal pattern of heroin effects results from the sequential, only partially overlapping, actions not only of 6-MAM, morphine, and M6G, but also of heroin per se, which, therefore, should not be seen as a mere brain-delivery system for its active metabolites. We will first review the literature concerning the pharmacokinetics and pharmacodynamics of heroin and its metabolites, then examine their neural and behavioral effects, and finally discuss the possible implications of these data for a better understanding of opioid reward and heroin addiction. By so doing we hope to highlight research topics to be investigated by future clinical and pre-clinical studies.
Topics: Humans; Heroin; Analgesics, Opioid; Morphine Derivatives; Morphine; Heroin Dependence
PubMed: 37031205
DOI: 10.1038/s41398-023-02406-5 -
Bioengineered Dec 2021Morphine tolerance poses a great challenge for clinicians, whose pathogenesis has a close connection with microglial activation and neuroinflammation. Dihydroartemisinin...
Morphine tolerance poses a great challenge for clinicians, whose pathogenesis has a close connection with microglial activation and neuroinflammation. Dihydroartemisinin (DHA) that derives from artemisinin, may serve as a potential anti-inflammatory drug. In this study, the effects as well as the underlying mechanism of DHA on suppressing microglial activation and neuroinflammation were explored. The microglial cell line BV-2 cells were induced by morphine and treated with DHA or minocycline. With the application of CCK-8, the cell viability was detected. Western blot was employed to assess the expressions of Ki67, IBa-1, and TLR4 and quantitative real-time PCR (qRT-PCR) was adopted to evaluate miRNA-16 (miR-16) expression. With the adoption of ELISA kits and qRT-PCR, the release of inflammatory cytokines was evaluated. Besides, luciferase reporter assay was applied to testify the binding relationship between miR-16 and TLR4. NF-κB expression was measured by immunofluorescence. DHA reduced cell viability and decreased protein expression of Ki67 and IBa-1 in morphine-induced BV-2 cells. Additionally, DHA contributed to the declined release of pro-inflammatory cytokines. miR-16 was down-regulated by morphine but was up-regulated by DHA concentration-dependently in BV-2 cells. The inhibition of miR-16 partly abolished the inhibitory effects of DHA on morphine-induced microglial activation and neuroinflammation. Moreover, TLR4 was found to be bound to miR-16, and the inhibitory effect of DHA on TLR4/NF-κB was partly reversed by miR-16 inhibition. In conclusion, DHA remarkably suppressed microglial activation and neuroinflammation through regulating miR-16-mediated TLR4/NF-κB signaling. This study may provide a new solution to improve clinical analgesic efficacy of morphine.
Topics: Animals; Artemisinins; Cell Line; Gene Expression Regulation; Inflammation; Mice; Microglia; Morphine; Nerve Tissue Proteins
PubMed: 34854364
DOI: 10.1080/21655979.2021.1982311 -
Canadian Journal of Anaesthesia =... Oct 2017
Topics: Analgesics, Opioid; Blood-Brain Barrier; Brain; Morphine
PubMed: 28721688
DOI: 10.1007/s12630-017-0932-y -
Addiction Biology May 2022Levamisole is a veterinary anthelmintic drug and a common adulterant of misused drugs. This study analyses the lethal, antinociceptive and haematological effects...
Levamisole is a veterinary anthelmintic drug and a common adulterant of misused drugs. This study analyses the lethal, antinociceptive and haematological effects produced by acute or repeated levamisole administration by itself or combined with morphine. Independent groups of male Swiss Webster mice were i.p. injected with 100 mg/kg morphine, 31.6 mg/kg levamisole (lethal doses at 10%, LD ) or the same doses combined. Naloxone pretreatment (10 mg/kg, i.p.) prevented morphine-induced death, as did 2.5 mg/kg, i.p. mecamylamine with levamisole. Co-administration of levamisole and morphine (Lvm + Mor) increased lethality from 10% to 80%. This augmented effect was prevented by 30 mg/kg, i.p. naloxone and reduced with 10 mg/kg naloxone plus 2.5 mg/kg, i.p. mecamylamine. In independent groups of mice, 17.7 mg/kg, i.p. levamisole antagonized the acute morphine's antinociceptive effect evaluated in the tail-flick test. Repeated 17.7 mg/kg levamisole administration (2×/day/3 weeks) did not affect tolerance development to morphine (10 mg/kg, 3×/day/1 week). Blood samples obtained from mice repeatedly treated with levamisole showed leukopenia and neutropenia. Morphine also produced neutropenia, increased erythrocyte count and other related parameters (e.g. haemoglobin). Lvm + Mor had similar effects on leukocyte and neutrophil counts to those seen with levamisole only, but no erythrocyte-related alterations were evident. Blood chemistry analysis did not indicate liver damage but suggested some degree of electrolyte balance impairment. In conclusion, Lvm + Mor increased death risk, altered morphine-induced antinociceptive effects and produced haematologic abnormalities. The importance of studying combinations of drugs of abuse lies in the fact that drug users frequently combine drugs, which are commonly adulterated.
Topics: Analgesics; Animals; Levamisole; Male; Mecamylamine; Mice; Morphine; Naloxone; Neutropenia
PubMed: 35470549
DOI: 10.1111/adb.13166 -
Pharmacology & Therapeutics Jan 2023Morphine prescribed for analgesia has caused drug-related deaths at an estimated incidence of 0.3% to 4%. Morphine has pharmacological properties that make it... (Review)
Review
Morphine prescribed for analgesia has caused drug-related deaths at an estimated incidence of 0.3% to 4%. Morphine has pharmacological properties that make it particularly difficult to assess the causality of morphine administration with a patient's death, such as its slow transfer between plasma and central nervous sites of action and the existence of the active metabolite morphine-6-glucuronide with opioid agonistic effects, Furthermore, there is no well-defined toxic dose or plasma/blood concentration for morphine. Dosing is often adjusted for adequate pain relief. Here, we summarize reported deaths associated with morphine therapy, including associated morphine exposure and modulating patient factors such as pharmacogenetics, concomitant medications, or comorbidities. In addition, we systematically analyzed published numerical information on the stability of concentrations of morphine and its relevant metabolites in biological samples collected postmortem. A medicolegal case is presented in which the causality of morphine administration with death was in dispute and pharmacokinetic modeling was applied to infer the administered dose. The results of this analytical review suggest that (i) inference from postmortem blood concentrations to the morphine dose administered has low validity and (ii) causality between a patient's death and the morphine dose administered remains a highly context-dependent and collaborative assessment among experts from different medical specialties.
Topics: Humans; Morphine; Analgesics, Opioid; Data Science; Morphine Derivatives; Pain
PubMed: 36423714
DOI: 10.1016/j.pharmthera.2022.108312 -
European Journal of Pharmacology May 2020Morphine-3-glucuronide (M3G), the main metabolite of morphine, has been implicated in the development of tolerance and of opioid-induced hyperalgesia, both limiting the...
Morphine-3-glucuronide (M3G), the main metabolite of morphine, has been implicated in the development of tolerance and of opioid-induced hyperalgesia, both limiting the analgesic use of morphine. We evaluated the acute and chronic effects of M3G and morphine as well as development of antinociceptive cross-tolerance between morphine and M3G after intrathecal administration and assessed the expression of pain-associated neurotransmitter substance P in the spinal cord. Sprague-Dawley rats received intrathecal M3G or morphine twice daily for 6 days. Nociception and tactile allodynia were measured with von Frey filaments after acute and chronic treatments. Substance P levels in the dorsal horn of the spinal cord were determined by immunohistochemistry after 4-day treatments. Acute morphine caused antinociception as expected, whereas acute M3G caused tactile allodynia, as did both chronic M3G and morphine. Chronic M3G also induced antinociceptive cross-tolerance to morphine. M3G and morphine increased substance P levels similarly in the nociceptive laminae of the spinal cord. This study shows that chronic intrathecal M3G sensitises animals to mechanical stimulation and elevates substance P levels in the nociceptive laminae of the spinal cord. Chronic M3G also induces antinociceptive cross-tolerance to morphine. Thus, chronic M3G exposure might contribute to morphine-induced tolerance and opioid-induced hyperalgesia.
Topics: Animals; Central Nervous System Stimulants; Disease Models, Animal; Drug Administration Schedule; Drug Tolerance; Humans; Hyperalgesia; Injections, Spinal; Male; Morphine; Morphine Derivatives; Nociception; Pain Measurement; Rats; Spinal Cord; Substance P
PubMed: 32112778
DOI: 10.1016/j.ejphar.2020.173021 -
The Annals of Pharmacotherapy Mar 2016To evaluate acute traumatic pain protocols and to suggest optimization by characterizing opioid pharmacokinetics and pharmacodynamics (PK-PD). (Review)
Review
OBJECTIVE
To evaluate acute traumatic pain protocols and to suggest optimization by characterizing opioid pharmacokinetics and pharmacodynamics (PK-PD).
DATA SOURCES
MEDLINE (1946 to November 2015), EMBASE (1974 to November 2015), International Pharmaceutical Abstracts (1970 to December 2014), and Cochrane Database of Systematic Reviews (2005 to November 2015).
KEYWORDS
morphine, hydromorphone, fentanyl, trauma, acute pain, intravenous, opioid, pharmacokinetics, and pharmacodynamics.
STUDY SELECTION AND DATA EXTRACTION
Literature characterizing opioid PK-PD was included. Additionally, studies evaluatingoutcomes of opioids for acute severe pain in adult trauma patients were selected.
DATA SYNTHESIS
PK-PD literature suggests that morphine exhibits an effect delay of 1.6 to 4.8 hours; however, clinical significance is doubtful. The relative onset of morphine is approximately 6 minutes, and duration, 96 minutes. Morphine 0.1 mg/kg IV then 0.05 mg/kg every 5 minutes achieved pain control in 40% of patients at 10 minutes and 76% at 60 minutes. The effect delay of hydromorphone (orally) is 18 to 38 minutes; its relative onset (IV), 5 minutes; and duration, 120 minutes. Hydromorphone every 15 minutes achieved variable success in clinical trials. The effect delay of fentanyl IV is 16.4 minutes; relative onset, 2 minutes; and duration, 7 minutes. One randomized controlled trial used fentanyl 0.1 µg/kg IV every 5 minutes.
CONCLUSIONS
Further integration of opioid PK-PD into acutepain protocols is possible. One opioid should not be deemed more effective but rather titrated to effect. Morphine and hydromorphone can be titrated IV every 5 minutes until adequate pain control. Fentanyl can be titrated every 3 minutes.
Topics: Analgesics, Opioid; Fentanyl; Humans; Hydromorphone; Morphine; Pain; Pain Management; Pain Measurement; Wounds and Injuries
PubMed: 26739277
DOI: 10.1177/1060028015625659 -
Forensic Science International Aug 2019Brain tissue is a useful supplement to blood in postmortem investigations, but reference concentrations are scarce for many opioids. Heroin cases may be difficult to...
Brain tissue is a useful supplement to blood in postmortem investigations, but reference concentrations are scarce for many opioids. Heroin cases may be difficult to distinguish from morphine cases as heroin and its metabolites are rapidly degraded. We present concentrations from brain and blood and brain-blood ratios of 98 cases where morphine was quantified. These cases were grouped according to the cause of death: A: The compound was solely assumed to have caused a fatal intoxication. B: The compound presumably contributed to a fatal outcome in combination with other drugs, alcohol or disease. C: The compound was not regarded to be related to the cause of death. The cases were further classified as heroin cases if 6-acetyl-morphine or noscapine were detected. The analyses were carried out using solid-phase extraction or protein precipitation followed by ultra high-performance liquid chromatography coupled to mass spectrometry. The average brain-blood ratios of morphine were 1.2 and 1.8 for 69 morphine and 29 heroin cases, respectively. Differences in the brain-blood ratios were found for cases where heroin and morphine were involved in the cause of death, either in combination or on its own (P<0.001 and P=0.004, respectively). However, the overlap between morphine and heroin cases precludes the use of the brain-blood ratio to distinguish heroin from morphine intake. Morphine-6-glucuronide and 6-acetyl-morphine were quantified in brain and blood in a subset of the samples, yielding median brain-blood ratios of 5.1 and 8.3, respectively. The brain concentrations may aid the toxicological investigation in cases where heroin or morphine intoxications are suspected, but blood is not available.
Topics: Brain Chemistry; Chromatography, Liquid; Drug Overdose; Forensic Toxicology; Heroin; Humans; Mass Spectrometry; Morphine; Morphine Derivatives; Narcotics; Noscapine; Poisoning
PubMed: 31226641
DOI: 10.1016/j.forsciint.2019.06.007 -
The American Journal of the Medical... Sep 2015
Topics: Analgesics, Opioid; Gastroparesis; Humans; Male; Middle Aged; Morphine; Tomography, X-Ray Computed
PubMed: 25798832
DOI: 10.1097/MAJ.0000000000000450 -
Clinical Pharmacokinetics Jun 2016Morphine dosing can be challenging in terminally ill adult patients due to the heterogeneous nature of the population and the difficulty of accurately assessing pain... (Observational Study)
Observational Study
BACKGROUND AND OBJECTIVE
Morphine dosing can be challenging in terminally ill adult patients due to the heterogeneous nature of the population and the difficulty of accurately assessing pain during sedation. To determine the pharmacokinetics of morphine, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) in this population, and to find clinically relevant parameters for dose individualisation, we performed a population pharmacokinetic analysis.
METHODS
Blood samples were randomly collected from 47 terminally ill patients in both the pre-terminal and terminal phases. Nonlinear mixed-effects modelling (NONMEM) was used to develop a population pharmacokinetic model and perform covariate analysis.
RESULTS
The data were accurately described by a two-compartment model for morphine with two one-compartment models for both its metabolites. Typical morphine clearance was 48 L/h and fell exponentially by more than 10 L/h in the last week before death. Decreased albumin levels and a decreased estimated glomerular filtration rate (eGFR) resulted in lower metabolite clearance. Between-subject variability in clearance was 52 % (morphine), 75 % (M3G) and 79 % (M6G), and changed to 53, 29 and 34 %, respectively, after inclusion of the covariates.
CONCLUSIONS
Our results show that morphine clearance decreased up to the time of death, falling by more than 10 L/h (26 %) in the last week before death, and that M3G and M6G accumulated due to decreased renal function. Further studies are warranted to determine whether dose adjustment of morphine is required in terminally ill patients.
Topics: Adult; Aged; Aged, 80 and over; Analgesics, Opioid; Computer Simulation; Female; Glomerular Filtration Rate; Humans; Male; Metabolic Clearance Rate; Middle Aged; Models, Biological; Morphine; Morphine Derivatives; Prospective Studies; Serum Albumin; Terminally Ill
PubMed: 26715216
DOI: 10.1007/s40262-015-0345-4