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Abstract
Abstract
Background
Respiratory depression is a potentially fatal complication of opioid use, which may be exacerbated by simultaneous ethanol intake. In this three-way sequential crossover dose-escalating study, the influence of coadministration of oral oxycodone and intravenous ethanol was assessed on resting ventilation, apneic events and the hypercapnic ventilatory response in healthy young and older volunteers.
Methods
Twelve young (21 to 28 yr) and 12 elderly (66 to 77 yr) opioid-naive participants ingested one 20 mg oxycodone tablet combined with an intravenous infusion of 0, 0.5, or 1 g/l ethanol. Resting respiratory variables and the primary outcome, minute ventilation at isohypercapnia (end-tidal partial pressure of carbon dioxide of 55 mmHg or VE55), were obtained at regular intervals during treatment.
Results
Oxycodone reduced baseline minute ventilation by 28% (P < 0.001 vs. control). Ethanol caused a further decrease of oxycodone-induced respiratory depression by another 19% at 1 g/l ethanol plus oxycodone (P < 0.01 vs. oxycodone). Ethanol combined with oxycodone caused a significant increase in the number of apneic events measured in a 6-min window with a median (range) increase from 1 (0 to 3) at 0 g/l ethanol to 1 (0 to 11) at 1 g/l ethanol (P < 0.01). Mean (95% CI) VE55 decreased from 33.4 (27.9 to 39.0) l/min (control) to 18.6 (15.6 to 21.6) l/min (oxycodone, P < 0.01 vs. control) and to 15.7 (12.7 to 18.6) l/min (oxycodone combined with ethanol, 1 g/l; P < 0.01 vs. oxycodone).
Conclusions
Ethanol together with oxycodone causes greater ventilatory depression than either alone, the magnitude of which is clinically relevant. Elderly participants were more affected than younger volunteers.
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Withey SL, Hill R, Lyndon A, Dewey WL, Kelly E, Henderson G. Effect of Tamoxifen and Brain-Penetrant Protein Kinase C and c-Jun N-Terminal Kinase Inhibitors on Tolerance to Opioid-Induced Respiratory Depression in Mice. J Pharmacol Exp Ther 2017; 361:51-59. [PMID: 28130265 DOI: 10.1124/jpet.116.238329] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 01/25/2017] [Indexed: 01/20/2023] Open
Abstract
Respiratory depression is the major cause of death in opioid overdose. We have previously shown that prolonged treatment of mice with morphine induces profound tolerance to the respiratory-depressant effects of the drug (Hill et al., 2016). The aim of the present study was to investigate whether tolerance to opioid-induced respiratory depression is mediated by protein kinase C (PKC) and/or c-Jun N-terminal kinase (JNK). We found that although mice treated for up to 6 days with morphine developed tolerance, as measured by the reduced responsiveness to an acute challenge dose of morphine, administration of the brain-penetrant PKC inhibitors tamoxifen and calphostin C restored the ability of acute morphine to produce respiratory depression in morphine-treated mice. Importantly, reversal of opioid tolerance was dependent on the nature of the opioid ligand used to induce tolerance, as these PKC inhibitors did not reverse tolerance induced by prolonged treatment of mice with methadone nor did they reverse the protection to acute morphine-induced respiratory depression afforded by prolonged treatment with buprenorphine. We found no evidence for the involvement of JNK in morphine-induced tolerance to respiratory depression. These results indicate that PKC represents a major mechanism underlying morphine tolerance, that the mechanism of opioid tolerance to respiratory depression is ligand-dependent, and that coadministration of drugs with PKC-inhibitory activity and morphine (as well as heroin, largely metabolized to morphine in the body) may render individuals more susceptible to overdose death by reversing tolerance to the effects of morphine.
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Affiliation(s)
- Sarah L Withey
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, United Kingdom (S.L.W., R.H., A.L., E.K., G.H.); and Virginia Commonwealth University, Richmond, Virginia (W.L.D.)
| | - Rob Hill
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, United Kingdom (S.L.W., R.H., A.L., E.K., G.H.); and Virginia Commonwealth University, Richmond, Virginia (W.L.D.)
| | - Abigail Lyndon
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, United Kingdom (S.L.W., R.H., A.L., E.K., G.H.); and Virginia Commonwealth University, Richmond, Virginia (W.L.D.)
| | - William L Dewey
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, United Kingdom (S.L.W., R.H., A.L., E.K., G.H.); and Virginia Commonwealth University, Richmond, Virginia (W.L.D.)
| | - Eamonn Kelly
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, United Kingdom (S.L.W., R.H., A.L., E.K., G.H.); and Virginia Commonwealth University, Richmond, Virginia (W.L.D.)
| | - Graeme Henderson
- School of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, United Kingdom (S.L.W., R.H., A.L., E.K., G.H.); and Virginia Commonwealth University, Richmond, Virginia (W.L.D.)
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Abstract
Heroin overdose deaths in the Unites States more than tripled from 2010 to 2014, reaching almost 11,000 per year. Despite the use of the term “overdose,” many of these victims died after self-administering an amount of opiate that would not be expected to be fatal for these drug-experienced, and drug-tolerant, individuals. Various explanations of this overdose mystery have been proposed. I describe an explanation based on Pavlovian conditioning. Organisms associate cues present at the time of drug administration with the systemic effect of the drug. These drug-predictive cues come to elicit responses that attenuate the effect of a drug. Such anticipatory conditional responses mediate chronic tolerance. If the drug is administered in the presence of novel cues, tolerance fails to occur and the victim suffers an overdose. Overdose prevention strategies should incorporate information about the contribution of drug-associated cues to drug tolerance.
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Affiliation(s)
- Shepard Siegel
- Department of Psychology, Neuroscience and Behaviour, McMaster University
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Lingford-Hughes A. Substitution treatment in addiction: there is more than one way.. Addiction 2016; 111:776-7. [PMID: 26913830 DOI: 10.1111/add.13288] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 12/21/2015] [Indexed: 11/28/2022]
Affiliation(s)
- Anne Lingford-Hughes
- Imperial College London, Neuropsychopharmacology Unit, Department of Medicine, Burlington Danes Building Hammersmith campus 160 Du Cane Road, London, W12 0NN, UK.
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Affiliation(s)
- Nora D Volkow
- From the National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD (N.D.V.); and the Treatment Research Institute, Philadelphia (A.T.M.)
| | - A Thomas McLellan
- From the National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD (N.D.V.); and the Treatment Research Institute, Philadelphia (A.T.M.)
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Hickman M, Macleod J, Degenhardt L. Commentary on Cousins et al. (2016): Accumulating evidence on risk of mortality on and off opioid substitution treatment. Addiction 2016; 111:83-4. [PMID: 26669528 DOI: 10.1111/add.13185] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 09/24/2015] [Indexed: 11/29/2022]
Affiliation(s)
- Matthew Hickman
- School of Social and Community Medicine, NIHR School of Public Health, NIHR School of Primary Care, NIHR Health Protection Research Unit in Evaluation, University of Bristol, Bristol, UK.
| | - John Macleod
- School of Social and Community Medicine, NIHR School of Public Health, NIHR School of Primary Care, NIHR Health Protection Research Unit in Evaluation, University of Bristol, Bristol, UK
| | - Louisa Degenhardt
- National Drug and Alcohol Research Centre, University of New South Wales, Sydney, Australia
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