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Differential Effects of a Novel Opioid Ligand UTA1003 on Antinociceptive Tolerance and Motor Behaviour. Pharmaceuticals (Basel) 2022; 15:ph15070789. [PMID: 35890089 PMCID: PMC9318816 DOI: 10.3390/ph15070789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 06/18/2022] [Accepted: 06/21/2022] [Indexed: 02/05/2023] Open
Abstract
Analgesic tolerance is a major problem in the clinic for the maintenance of opioid-induced long-term pain relief. Opioids with mixed activity on multiple opioid receptors promise reduced antinociceptive tolerance in preclinical studies, but these compounds typically show poor bioavailability upon oral, subcutaneous, intraperitoneal, or intravenous administration. We designed UTA1003 as a novel opioid that acts as a mu (MOP) and kappa (KOP) opioid receptor agonist and a partial agonist for delta (DOP) opioid receptor. In the present study, its antinociceptive effects, as well as its effects on antinociceptive tolerance and motor behaviour, were investigated in male rats. Acute antinociception was measured before (basal) and at different time points after subcutaneous injection of UTA1003 or morphine using the tail flick and hot plate assays. Various motor behavioural activities, including horizontal locomotion, rearing, and turning, were automatically measured in an open-field arena. The antinociceptive and behavioural effects of repeated administration of UTA1003 and morphine were determined over eight days. UTA1003 induced mild antinociceptive effects after acute administration but induced no tolerance after repeated treatment. Importantly, UTA1003 co-treatment with morphine prevented antinociceptive tolerance compared to morphine alone. UTA1003 showed less motor suppression than morphine in both acute and sub-chronic treatment regimens, while it did not affect morphine-induced motor suppression or hyper-excitation. Based on these activities, we speculate that UTA1003 crosses the blood-brain barrier after subcutaneous administration and, therefore, could be developed as a lead molecule to avoid opioid-induced antinociceptive tolerance and motor suppression. Further structural modifications to improve its antinociceptive effects, toxicity profile, and ADME parameters are nevertheless required.
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Walentiny DM, Komla E, Moisa LT, Mustafa MA, Poklis JL, Akbarali HI, Beardsley PM. Methylnaltrexone crosses the blood-brain barrier and attenuates centrally-mediated behavioral effects of morphine and oxycodone in mice. Neuropharmacology 2020; 185:108437. [PMID: 33316279 DOI: 10.1016/j.neuropharm.2020.108437] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 10/27/2020] [Accepted: 12/04/2020] [Indexed: 11/18/2022]
Abstract
BACKGROUND Antagonism of peripheral opioid receptors by methylnaltrexone (MNTX) was recently proposed as a potential mechanism to attenuate the development of opioid analgesic tolerance based on experiments conducted in mice. However, reports indicate that MNTX is demethylated to naltrexone (NTX) in mice, and NTX may subsequently cross the blood-brain barrier to antagonize centrally-mediated opioid effects. The goal of this study was to determine whether MNTX alters centrally-mediated behaviors elicited by the opioid analgesics, morphine and oxycodone, and to quantify concentrations of MNTX and NTX in blood and brain following their administration in mice. METHODS Combinations of MNTX and morphine were tested under acute and chronic conditions in thermal nociceptive assays. Effects of MNTX and NTX pretreatment were assessed in an oxycodone discrimination operant procedure. Blood and brain concentrations of these antagonists were quantified after their administration using liquid chromatography-mass spectrometry. RESULTS MNTX dose-dependently attenuated acute and chronic morphine antinociception. MNTX and NTX dose-dependently antagonized the discriminative stimulus effects of oxycodone. MNTX and NTX were detected in both blood and brain after administration of MNTX, confirming its demethylation and demonstrating that MNTX itself can cross the blood-brain barrier. CONCLUSIONS These results provide converging behavioral and analytical evidence that MNTX administration in mice attenuates centrally-mediated effects produced by opioid analgesics and results in functional concentrations of MNTX and NTX in blood and brain. Collectively, these findings indicate that MNTX cannot be administered systemically in mice for making inferences that its effects are peripherally restricted.
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Affiliation(s)
- D Matthew Walentiny
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, 1217 E. Marshall Street, Richmond, VA, 23298-0613, USA.
| | - Essie Komla
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, 1217 E. Marshall Street, Richmond, VA, 23298-0613, USA
| | - Léa T Moisa
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, 1217 E. Marshall Street, Richmond, VA, 23298-0613, USA
| | - Mohammed A Mustafa
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, 1217 E. Marshall Street, Richmond, VA, 23298-0613, USA
| | - Justin L Poklis
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, 1217 E. Marshall Street, Richmond, VA, 23298-0613, USA
| | - Hamid I Akbarali
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, 1217 E. Marshall Street, Richmond, VA, 23298-0613, USA
| | - Patrick M Beardsley
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, 1217 E. Marshall Street, Richmond, VA, 23298-0613, USA; Institute for Drug and Alcohol Studies & Center for Biomarker Research and Precision Medicine, Virginia Commonwealth University, 410 N. 12th Street, PO Box 980613, Richmond, VA, 23298-0613, USA
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Blomqvist KJ, Dudek KA, Viisanen H, Mätlik K, Ahlström FHG, Laitila J, Kalso EA, Rauhala PV, Lilius TO. Antagonism of peripheral opioid receptors by methylnaltrexone does not prevent morphine tolerance in rats. J Neurosci Res 2020; 100:329-338. [PMID: 32459013 DOI: 10.1002/jnr.24638] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 04/16/2020] [Accepted: 04/20/2020] [Indexed: 11/10/2022]
Abstract
Opioids are effective analgesics in the management of severe pain. However, tolerance, leading to dose escalation and adverse effects are significant limiting factors in their use. The role of peripheral opioid receptors in analgesia has been discussed especially under inflammatory conditions. The results from pharmacological and conditional knockout studies together do not provide a clear picture of the contribution of peripheral opioid receptors on antinociceptive tolerance and this needs to be evaluated. Therefore, we studied whether the peripherally restricted opioid receptor antagonist, methylnaltrexone (MNTX), could prevent morphine tolerance without attenuating the antinociceptive effect of morphine. Male Sprague-Dawley rats were treated for 7 days with increasing subcutaneous doses of morphine (5-30 mg/kg) and were coadministered saline, MNTX (0.5 or 2 mg/kg), or naltrexone (NTX; 2 mg/kg). Nociception was assessed with tail-flick, hotplate, and von Frey tests. Morphine, MNTX, and NTX concentrations in the plasma, brain, and spinal cord were measured by liquid chromatography-tandem mass spectrometry. In acute coadministration, NTX, but not MNTX, abolished the acute antinociceptive effects of morphine in all nociceptive tests. The antinociceptive tolerance after repeated morphine administration was also prevented by NTX but not by MNTX. MNTX penetrated to the spinal cord and the brain to some extent after repeated administration. The results do not support the use of MNTX for preventing opioid tolerance and also suggest that morphine tolerance is mediated by central rather than peripheral opioid receptors in the rat.
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Affiliation(s)
- Kim Juhani Blomqvist
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Individualized Drug Therapy Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Katarzyna Anna Dudek
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Individualized Drug Therapy Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Hanna Viisanen
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Individualized Drug Therapy Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Kert Mätlik
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Individualized Drug Therapy Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Fredrik Harry Gustav Ahlström
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Individualized Drug Therapy Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Jouko Laitila
- Individualized Drug Therapy Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Department of Clinical Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki University Hospital, Finland
| | - Eija Anneli Kalso
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Department of Anaesthesiology, Intensive Care Medicine, and Pain Medicine, University of Helsinki, Helsinki University Hospital, Helsinki, Finland
| | - Pekka Veli Rauhala
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Individualized Drug Therapy Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Tuomas Olavi Lilius
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Individualized Drug Therapy Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Department of Clinical Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki University Hospital, Finland.,Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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The behavioral effects of a mixed efficacy antinociceptive peptide, VRP26, following chronic administration in mice. Psychopharmacology (Berl) 2016; 233:2479-87. [PMID: 27117141 PMCID: PMC5068912 DOI: 10.1007/s00213-016-4296-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 04/07/2016] [Indexed: 01/08/2023]
Abstract
RATIONALE VRP26 displays mu opioid receptor agonist and delta opioid receptor antagonist activity in vitro, a pharmacological profile purported to produce reduced tolerance, dependence, and rewarding effects. We hypothesized that VRP26 would display reduced adverse effects after chronic administration as compared with the traditional opioid analgesic fentanyl. OBJECTIVE The aim of this study is to explore the development of tolerance, dependence, and conditioned place preference of VRP26 as compared with the traditional opioid analgesic fentanyl. METHODS The antinociceptive effects of VRP26 and fentanyl were assessed using the mouse warm water tail withdrawal (WWTW) assay. Measurement of antinociceptive tolerance and physical dependence occurred after 7 days of continuous administration of either fentanyl (0.3 mg/kg/day) or VRP26 (10 mg/kg/day); tolerance was measured by a shift in the antinociceptive dose response curve in the WWTW assay. Physical dependence was determined by observation of withdrawal symptoms after precipitated withdrawal. Rewarding effects were measured by the ability of VRP26 or fentanyl to produce conditioned place preference. RESULTS Fentanyl produced significant tolerance and dependence, as well as significant conditioned place preference. VRP26 produced neither tolerance nor physical dependence, nor did it produce significant conditioned place preference. CONCLUSIONS These results suggest that chronic treatment with VRP26 may produce less tolerance or physical dependence than chronic treatment with clinically available mu opioid analgesics such as fentanyl. Additionally, VRP26 produces less rewarding effects than fentanyl. This desirable in vivo profile may be due to the mixed efficacy nature of VRP26 and could provide the framework for safer opioid analgesics.
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Stein C, Machelska H. Modulation of Peripheral Sensory Neurons by the Immune System: Implications for Pain Therapy. Pharmacol Rev 2011; 63:860-81. [DOI: 10.1124/pr.110.003145] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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Opioid receptors and opioid peptide-producing leukocytes in inflammatory pain--basic and therapeutic aspects. Brain Behav Immun 2010; 24:683-94. [PMID: 19879349 DOI: 10.1016/j.bbi.2009.10.013] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2009] [Revised: 10/22/2009] [Accepted: 10/24/2009] [Indexed: 12/12/2022] Open
Abstract
This review summarizes recent findings on neuro-immune mechanisms underlying opioid-mediated inhibition of pain. The focus is on events occurring in peripheral injured tissues that lead to the sensitization and excitation of primary afferent neurons, and on the modulation of such mechanisms by immune cell-derived opioid peptides. Primary afferent neurons are of particular interest from a therapeutic perspective because they are the initial generators of impulses relaying nociceptive information towards the spinal cord and the brain. Thus, if one finds ways to inhibit the sensitization and/or excitation of peripheral sensory neurons, subsequent central events such as wind-up, sensitization and plasticity may be prevented. This is in part achieved by endogenously released immune cell-derived opioid peptides within inflamed tissue. In addition, exogenous opioid receptor ligands that selectively modulate primary afferent function and do not cross the blood-brain barrier, avoid centrally mediated untoward side effects of conventional analgesics (e.g., opioids, anticonvulsants). This article discusses peripheral opioid receptors and their signaling pathways, opioid peptide-producing/secreting inflammatory cells and arising therapeutic perspectives.
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Guay DRP. Methylnaltrexone Methobromide: The First Peripherally Active, Centrally Inactive Opioid Receptor-Antagonist Clinical Review. ACTA ACUST UNITED AC 2009; 24:210-26. [DOI: 10.4140/tcp.n.2009.210] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Harris AC, Gewirtz JC. Acute opioid dependence: characterizing the early adaptations underlying drug withdrawal. Psychopharmacology (Berl) 2005; 178:353-66. [PMID: 15696323 DOI: 10.1007/s00213-005-2155-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2004] [Accepted: 12/24/2004] [Indexed: 11/26/2022]
Abstract
RATIONALE While opioid withdrawal is typically studied under conditions of chronic (i.e., continuous) drug administration, withdrawal signs can also be demonstrated in both humans and animals after a single opioid exposure. This phenomenon, termed acute dependence, may be useful in understanding the early stages of opioid dependence and addiction. OBJECTIVE This review provides an overview of acute dependence by comparing withdrawal from acute and chronic opioid exposure across dimensions ranging from symptomatology to neural substrates. Assessment of repeated withdrawals from acute opioid administration is also presented as a tool for better understanding the adaptive changes induced by multiple drug exposures. CONCLUSIONS Although not identical phenomena, acute and chronic dependence share a number of characteristics. Examining potentiations of withdrawal severity across multiple acute opioid exposures may be especially valuable in characterizing the development of drug dependence. Further study of acute dependence promises to lead to more effective treatments for opioid withdrawal and addiction.
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Affiliation(s)
- Andrew C Harris
- Department of Psychology, University of Minnesota, 75 East River Road, Minneapolis, MN 55455, USA
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Abstract
UNLABELLED Opioid medication is the mainstay of therapy for severe acute and chronic pain. Unfortunately, the side effects of these medications can affect patient comfort and safety, thus limiting their proven therapeutic potential. Whereas the main analgesic effects of opioids are centrally mediated, many of the common side effects are mediated via peripheral receptors. Novel peripheral opioid antagonists have been recently introduced that can block the peripheral actions of opioids without affecting centrally mediated analgesia. We review the clinical and experimental evidence of their efficacy in ameliorating opioid side effects and consider what further information might be useful in defining their role. IMPLICATIONS The major analgesic effects of opioid medication are mediated within the brain and spinal cord. Many of the side effects of opioids are caused by activation of receptors outside these areas. Recently developed peripherally restricted opioid antagonists have the ability to block many opioid side effects without affecting analgesia.
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Affiliation(s)
- John J Bates
- *Department of Anaesthesia and Intensive Care Medicine, Cork University Hospital, Ireland; and †Clinical Research, Adolor Inc, Exton, Pennsylvania
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Ibrahim MM, Mata HP, Chawla M, Lai J, Porreca F, Malan TP. Allodynia and hyperalgesia produced by specific inhibition of spinal c-fos expression: lack of correlation with dynorphin content. THE JOURNAL OF PAIN 2003; 2:241-9. [PMID: 14622822 DOI: 10.1054/jpai.2001.23135] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Inhibition of spinal Fos expression increases formalin-induced nociception and decreases spinal prodynorphin messenger ribonucleic acid (mRNA), suggesting that Fos modulates nociception by inducing dynorphin synthesis. This study tests the hypothesis that Fos modulates sensitivity to other somatic stimuli, such that inhibition of Fos expression will result in tactile allodynia and thermal hyperalgesia. In addition, it correlates the somatosensory effects of inhibition of Fos expression with spinal dynorphin content. Antisense oligodeoxynucleotide (ODN) to c-fos mRNA was administered by intrathecal infusion. Tactile sensitivity was tested by probing the hindpaw with von Frey filaments. Thermal sensitivity was quantitated by using withdrawal latency to radiant heat. Two percent formalin was injected into the dorsal hindpaw, and flinches were quantitated. Fos was quantitated by counting immunoreactive cells. Dynorphin was measured by immunoassay. Intrathecal antisense, but not mismatch, ODN resulted in tactile allodynia, thermal hyperalgesia, and hyperalgesia to formalin-induced nociception. Antisense ODN decreased Fos-like immunoreactivity after formalin injection but did not alter Jun-like immunoreactivity. Antisense ODN had differing effects on spinal dynorphin content, depending on the method of administration. These experiments show a role of Fos in modulating somatosensory sensitivity and suggest that induction of dynorphin synthesis is not the sole mechanism by which Fos does so.
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Affiliation(s)
- M M Ibrahim
- Graduate Program in Pharmacology and Toxicology, The University of Arizona, Tucson, 85724, USA
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Lewanowitsch T, Irvine RJ. Naloxone methiodide reverses opioid-induced respiratory depression and analgesia without withdrawal. Eur J Pharmacol 2002; 445:61-7. [PMID: 12065195 DOI: 10.1016/s0014-2999(02)01715-6] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Illicit opioid overdoses are a significant problem throughout the world, with most deaths being attributed to opioid-induced respiratory depression which may involve peripheral mechanisms. The current treatment for overdoses is naloxone hydrochloride, which is effective but induces significant withdrawal. We propose that selectively peripherally acting opioid receptor antagonists, such as naloxone methiodide, could reverse respiratory depression without inducing predominantly centrally mediated withdrawal. Acute administration of morphine (300 mg/kg, i.p.) was found to significantly depress respiratory rate and induce analgesia (P<0.0001). Both naloxone hydrochloride and naloxone methiodide were able to reverse these effects but naloxone methiodide precipitated no significant withdrawal. Naloxone methiodide was also able to reverse opioid-induced respiratory depression (P<0.001) and antinociception (P<0.01) after chronic morphine administration (300 mg/kg/day for 5 days) without inducing significant withdrawal. Therefore, peripherally selective opioid receptor antagonists should be investigated as possible treatments for opioid-induced respiratory depression which do not induce adverse effects, such as withdrawal.
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Affiliation(s)
- Tanya Lewanowitsch
- Department of Clinical and Experimental Pharmacology, University of Adelaide, 5th Floor Medical School North, Adelaide, South Australia 5005, Australia.
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Kotake AN, Kuwahara SK, Burton E, McCoy CE, Goldberg LI. Variations in demethylation of N-methylnaltrexone in mice, rats, dogs, and humans. Xenobiotica 1989; 19:1247-54. [PMID: 2618077 DOI: 10.3109/00498258909043176] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
1. Rats and mice have a greater capacity than dogs or humans to N-demethylate the quaternary ammonium compound, N-methylnaltrexone. 2. In dogs, following the i.v. administration of N-[14C-methyl]methylnaltrexone, 50% of the radioactivity was excreted in the urine and an additional 30% in the faeces within 120 h. 3. In humans following the i.v. administration of 14C-N-methylnaltrexone, 40-60% of the radioactivity was excreted in the urine within the first 24 h. The plasma radioactivity-time curves indicated a biphasic decay and a short distribution phase between 6 and 9 min. with a longer elimination phase between 238 and 1320 min.
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Affiliation(s)
- A N Kotake
- Department of Pharmacological, University of Chicago, IL 60637
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Abstract
Quaternary ammonium derivatives of narcotic antagonists are commonly used in determining sites of action of opiates in the central nervous system and the periphery because it is widely assumed that they do not readily cross the blood-brain barrier, in contrast to their relatively non-polar tertiary counterparts. However, these compounds possess several unique pharmacological properties which have not been taken into consideration in the design of numerous investigations. This article reviews the current state of knowledge concerning the pharmacology of the quaternary narcotic antagonists, examines their use in physiological and behavioral studies of action of opiates, and proposes guidelines for the design of experiments involving these compounds.
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Dragonetti M, Bianchetti A, Sacilotto R, Giudice A, Ferrarese N, Cattaneo C, Manara L. Levallorphan methyl iodide (SR 58002), a potent narcotic antagonist with peripheral selectivity superior to that of other quaternary compounds. Life Sci 1983; 33 Suppl 1:477-80. [PMID: 6664228 DOI: 10.1016/0024-3205(83)90545-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The peripheral selectivity of the newer quaternary narcotic antagonist levallorphan methyl iodide (SR 58002) was found superior in mice to those of the previously available compounds N-allyl levallorphan (CM 32191), N-methyl nalorphine (MNph) and N-methyl naloxone (MNx). SR 58002 and MNph were the most potent (ID50, mg/kg s.c., 3.6 and 3.7) in preventing constipation by s.c. morphine (charcoal meal). Antinociception (hot-plate) of s.c. morphine was completely prevented by MNx, MNph and CM 32191 (ID50, mg/kg s.c., 1.6, 8.6 and 15.2) but only partially antagonized by 30 mg/kg s.c. SR 58002. Constipation elicited centrally by intracerebroventricular (i.c.v.) morphine was prevented by either s.c. MNx or MNph but not by SR 58002 or CM 32191, up to 60 mg/kg.
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