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Feng Y, Morato NM, Huang KH, Lin M, Cooks RG. High-throughput label-free opioid receptor binding assays using an automated desorption electrospray ionization mass spectrometry platform. Chem Commun (Camb) 2024. [PMID: 39007214 DOI: 10.1039/d4cc02346c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
The current opioid epidemic has incentivized the discovery of new non-addictive analgesics, a process that requires the screening of opioid receptor binding, traditionally performed using radiometric assays. Here we describe a label-free alternative based on high-throughput (1 Hz) ambient mass spectrometry for screening the receptor binding of new opioid analogues.
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Affiliation(s)
- Yunfei Feng
- Department of Chemistry, Bindley Bioscience Center, and Purdue Institute for Cancer Research, Purdue University, West Lafayette, IN 47907, USA.
| | - Nicolás M Morato
- Department of Chemistry, Bindley Bioscience Center, and Purdue Institute for Cancer Research, Purdue University, West Lafayette, IN 47907, USA.
| | - Kai-Hung Huang
- Department of Chemistry, Bindley Bioscience Center, and Purdue Institute for Cancer Research, Purdue University, West Lafayette, IN 47907, USA.
| | - Mina Lin
- Department of Chemistry, Bindley Bioscience Center, and Purdue Institute for Cancer Research, Purdue University, West Lafayette, IN 47907, USA.
| | - R Graham Cooks
- Department of Chemistry, Bindley Bioscience Center, and Purdue Institute for Cancer Research, Purdue University, West Lafayette, IN 47907, USA.
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Rajan RK, Engels M, Ramanathan M. Predicting phase-I metabolism of piceatannol: an in silico study. In Silico Pharmacol 2024; 12:52. [PMID: 38854674 PMCID: PMC11153392 DOI: 10.1007/s40203-024-00228-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 05/28/2024] [Indexed: 06/11/2024] Open
Abstract
Piceatannol is a natural compound found in plants and can be derived from resveratrol. While resveratrol has been extensively researched for its effects and how the body processes it, there are concerns about its use. These concerns include its limited absorption in the body, the need for specific dosages, potential interactions with other drugs, lack of standardization, and limited clinical evidence to support its benefits. Interestingly, Piceatannol, another compound derived from resveratrol, has received less attention from researchers but appears to offer advantages. It has better bioavailability and seems to have a more favorable therapeutic profile compared to resveratrol. Surprisingly, no previous attempts have been made to explore or predict the metabolites of piceatannol when it interacts with the enzyme cytochrome P450. This study aims to fill that gap by predicting how piceatannol is metabolized by cytochrome P450 and assessing any potential toxicity associated with its metabolites. This research is interesting because it's the first of its kind to investigate the metabolic fate of piceatannol, especially in the context of cytochrome P450. The findings have the potential to significantly contribute to the field of piceatannol research, particularly in the food industry where this compound has applications and implications. Graphical abstract
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Affiliation(s)
- Ravi Kumar Rajan
- Department of Pharmacology, School of Pharmaceutical Sciences, Girijananda Chowdhury University, Tezpur Campus, Tezpur, Assam India
- Present Address: Department of Pharmacology, Himalayan Pharmacy Institute, Majitar, East Sikkim 737136 India
| | - Maida Engels
- Department of Pharmaceutical Chemistry, PSG College of Pharmacy, Coimbatore, Tamil Nadu India
| | - Muthiah Ramanathan
- Department of Pharmacology, PSG College of Pharmacy, Coimbatore, Tamil Nadu India
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Ershad A, Shafiee Dolat Abadi S, Ebrahimian M, Hadeiy SK, Zamani N, Kolahi AA, Movafagh A, Hassanian-Moghaddam H. Association of the OPRM1 variant rs1799971 (A118G) and clinical manifestations in tramadol poisoned patients: a cross-sectional study. Clin Toxicol (Phila) 2024; 62:357-363. [PMID: 38946467 DOI: 10.1080/15563650.2024.2366921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 06/06/2024] [Indexed: 07/02/2024]
Abstract
INTRODUCTION The opioid receptor mu1 is a protein coding gene that can have different codes for a protein and may have variations (polymorphisms) affecting how opioids work. The aim of this study was to investigate the prevalence of the most common opioid receptor mu1 polymorphism (A118G) and any relationship between this polymorphism and features following tramadol overdose. MATERIALS AND METHODS This was a cross-sectional study of patients admitted with tramadol poisoning to an Iranian hospital. These patients were not taking any other drugs or medications and had no history of seizures. RESULTS The results showed that among the 83 patients included in the study, 57 (69 per cent) had the AA genotype, 25 (30 per cent) had the AG genotype, and one (1 per cent) had the GG genotype for the opioid receptor mu1 A118G polymorphism. Nausea and/or vomiting occurred in nine (11 per cent) patients and dizziness in 38 (46 per cent) patients. Serious adverse events included seizures in 51 (60 per cent) patients and respiratory failure requiring mechanical ventilation in 21 (25 per cent) patients. However, there was no significant association between the opioid receptor mu1 A118G polymorphism and these adverse events. DISCUSSION In our study, the frequency of the A allele was greater than the G allele, and the AA genotype was more prevalent than AG. The GG genotype was the least common among the polymorphisms of opioid receptor mu1 rs1799971. There was no significant association between the opioid receptor mu1 A118G polymorphism and symptoms in tramadol-poisoned patients. Although these allele proportions are similar to the results reported in other Caucasian populations, they are dissimilar to the findings in Chinese and Singaporean populations. In these Asian studies, the predominant allele was the G allele. It has been suggested that a mutated G allele will decrease the production of opioid receptor mu1-related messenger ribonucleic acid and related proteins, leading to fewer mu-opioid receptors in the brain. CONCLUSIONS This study found no significant association between the opioid receptor mu1 A118G polymorphism and adverse outcomes in tramadol-poisoned patients. However, more research is needed to draw more definitive conclusions due to the limited evidence and variability of opioid receptor mu1 polymorphisms in different populations.
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Affiliation(s)
- Ali Ershad
- School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | | | - Seyed Kaveh Hadeiy
- School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | - Ali-Asghar Kolahi
- Social Determinants of Health Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Abolfazl Movafagh
- Department of Medical Genetics, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hossein Hassanian-Moghaddam
- Social Determinants of Health Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- Next Step Drug and Alcohol Services, Mental Health Commission, Perth, Australia
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Lankhuijzen LM, Ridler T. Opioids, microglia, and temporal lobe epilepsy. Front Neurol 2024; 14:1298489. [PMID: 38249734 PMCID: PMC10796828 DOI: 10.3389/fneur.2023.1298489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 12/15/2023] [Indexed: 01/23/2024] Open
Abstract
A lack of treatment options for temporal lobe epilepsy (TLE) demands an urgent quest for new therapies to recover neuronal damage and reduce seizures, potentially interrupting the neurotoxic cascades that fuel hyper-excitability. Endogenous opioids, along with their respective receptors, particularly dynorphin and kappa-opioid-receptor, present as attractive candidates for controlling neuronal excitability and therapeutics in epilepsy. We perform a critical review of the literature to evaluate the role of opioids in modulating microglial function and morphology in epilepsy. We find that, in accordance with anticonvulsant effects, acute opioid receptor activation has unique abilities to modulate microglial activation through toll-like 4 receptors, regulating downstream secretion of cytokines. Abnormal activation of microglia is a dominant feature of neuroinflammation, and inflammatory cytokines are found to aggravate TLE, inspiring the challenge to alter microglial activation by opioids to suppress seizures. We further evaluate how opioids can modulate microglial activation in epilepsy to enhance neuroprotection and reduce seizures. With controlled application, opioids may interrupt inflammatory cycles in epilepsy, to protect neuronal function and reduce seizures. Research on opioid-microglia interactions has important implications for epilepsy and healthcare approaches. However, preclinical research on opioid modulation of microglia supports a new therapeutic pathway for TLE.
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Affiliation(s)
| | - Thomas Ridler
- Hatherly Laboratories, Department of Clinical and Biomedical Sciences, University of Exeter Medical School, University of Exeter, Exeter, United Kingdom
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Abdel-Salam OM, Mohamed Sayed MAEB, A. Omara E, A. Sleem A. The Protection by Vitamin E Against Tramadol-Induced Proconvulsant Effects and Brain Damage in Pentylenetetrazole-Induced Status Epilepticus in Rats. JOURNAL OF NEUROLOGY AND EPIDEMIOLOGY 2023; 8:1-10. [DOI: 10.12974/2309-6179.2023.08.01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
We investigated the effect of the opioid analgesic tramadol on the development of epileptic seizures and neuronal injury and the possible modulatory effect of vitamin E (Vit E) in rats with pentylenetetrazole (PTZ)-induced status epilepticus. Rats received repeated intraperitoneal (i.p.) injections of PTZ till the development of status epilepticus and were pretreated once with tramadol (30, 60 or 90 mg/kg), vitamin E (Vit E, 70 mg/kg) or both tramadol (90 mg/kg) and Vit E (70 mg/kg) prior to starting PTZ injections. Seizure scores, the latency time and the PTZ dose for each group required to reach status epilepticus were determined and histopathological examination of the brain tissue was done. Results indicated that tramadol produced both anticonvulsant and proconvulsant effects. The anticonvulsant effects of tramadol were observed for facial twitching (stage 1), convulsive body waves (stage 2), and myoclonic jerks and rearing (stage 3) and turn over onto one side position (stage 4) that were significantly inhibited by tramadol. In contrast, tonic-clonic convulsions (stage 5) were significantly increased by 60 or 90 mg/kg of tramadol as compared to PTZ control group. The mean latency and PTZ threshold dose for status epilepticus were markedly decreased after tramadol. The administration of Vit E exerted beneficial effects in decreasing epilepsy scores and increasing both the latency time and threshold dose of PTZ for reaching status epilepticus. Meanwhile, rats treated with both tramadol and Vit E exhibited significant increase in tonic-clonic convulsions and markedly shortened latency time to reach status epilepticus compared to those treated with only Vit E. In cerebral cortex and hippocampus, PTZ resulted in apoptotic cells, darkly stained degenerated and vacuolated neurons and gliosis. These pathological changes increased after tramadol but were markedly reduced by Vit E treatment. Collectively, these results suggest that: (i) tramadol exerts both anticonvulsant and proconvulsant effects; (ii) tramadol shortened the latency time and decreased the threshold dose of PTZ for evoking status epilepticus; (iii) PTZ-induced seizures and brain damage can be inhibited by Vit E; (iv) tramadol at high doses interferes with the effect of Vit E in inhibiting tonic-clonic convulsions and in reducing brain damage.
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ElShebiney SA, Elgohary R, Kenawy SH, El-Bassyouni GT, Hamzawy EMA. Zinc oxide calcium silicate composite attenuates acute tramadol toxicity in mice. BMC Pharmacol Toxicol 2023; 24:9. [PMID: 36759887 PMCID: PMC9912638 DOI: 10.1186/s40360-023-00647-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 01/23/2023] [Indexed: 02/11/2023] Open
Abstract
BACKGROUND Seizures are considered to be the most common symptom encountered in emergency- rushed tramadol-poisoned patients; accounting for 8% of the drug-induced seizure cases. Although, diazepam clears these seizures, the risk of central respiratory depression cannot be overlooked. Henceforth, three adsorbing composites were examined in a tramadol acute intoxication mouse model. METHODS Calcium Silicate (Wollastonite) either non-doped or wet doped with iron oxide (3%Fe2O3) or zinc oxide (30% ZnO) were prepared. The composites' adsorption capacity for tramadol was determined in vitro. Tramadol intoxication was induced in Swiss albino mice by a parenteral dose of 120 mg/kg. Proposed treatments were administered within 1 min at 5 increasing doses, i.p. The next 30 min, seizures were monitored as an intoxication symptom. Plasma tramadol concentration was recorded after two hours of administration. RESULTS The 3% Fe2O3-containing composite (CSFe3), was found to be composed of mainly wollastonite with very little alpha-hematite. On the other hand, hardystonite and wellimite were developed in the 30%ZnO-containing composite (CSZn3). Micro-round and irregular nano-sized microstructures were established (The particle size of CS was 56 nm, CSFe3 was 49 nm, and CSZn3 was 42 nm). The CSZn3 adsorption capacity reached 1497 mg of tramadol for each gram. Tramadol concentration was reduced in plasma and seizures were inhibited after its administration to mice at three doses. CONCLUSION The calcium silicate composite doped with ZnO presented a good resolution of tramadol-induced seizures accompanied by detoxification of blood, indicating its potential for application in such cases. Further studies are required.
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Affiliation(s)
- Shaimaa A. ElShebiney
- grid.419725.c0000 0001 2151 8157Narcotics, Ergogenics, and Poisons Department, National Research Centre, 33-El-Buhouth St., 12622 Dokki, Giza, Egypt
| | - Rania Elgohary
- grid.419725.c0000 0001 2151 8157Narcotics, Ergogenics, and Poisons Department, National Research Centre, 33-El-Buhouth St., 12622 Dokki, Giza, Egypt
| | - Sayed H. Kenawy
- grid.419725.c0000 0001 2151 8157Refractories, Ceramics and Building Materials Department, National Research Centre, 33 El Buhouth St, Dokki, Giza, 12622 Egypt
| | - Gehan T. El-Bassyouni
- grid.419725.c0000 0001 2151 8157Refractories, Ceramics and Building Materials Department, National Research Centre, 33 El Buhouth St, Dokki, Giza, 12622 Egypt
| | - Esmat M. A. Hamzawy
- grid.419725.c0000 0001 2151 8157Glass Research Department, National Research Centre, 33 El Buhouth St, Dokki, Giza, 12622 Egypt
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Omara-Reda H, Ouachikh O, Hamdi D, Lashin M, Hafidi A. Reinforcing effect of tramadol in the rat. Neurosci Lett 2023; 796:137053. [PMID: 36621588 DOI: 10.1016/j.neulet.2023.137053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 01/02/2023] [Accepted: 01/03/2023] [Indexed: 01/06/2023]
Abstract
Tramadol is one of the most commonly prescribed analgesic opioids in various pharmacopeias. Tramadol has been linked to abuse in recent clinical investigations. However, the behavioral effects and neural substrates of the drug have not been well characterized in preclinical studies. As a result, the present study investigated the effects of tramadol on behavioral sensitizations in rats. Its impacts on cellular and molecular alterations in the brain were also investigated. In conditioned place preference (CPP) paradigm, tramadol induced behavioral as well as motor sensitizations. These effects were dramatically reduced by intraperitoneal administration of naltrexone, an opioid receptor antagonist. Tramadol caused changes in several molecular markers (pERK1/2, Δ-FosB, PKCγ, PKMζ GAD67) in the anterior cingulate cortex, which could indicate an increase in excitation within this structure. Tramadol is demonstrated in the present study to be a reinforcing drug in rats, as it increased both behavioral and motor sensitizations. Tramadol's effects are most likely due to the high levels of excitation it causes in the brain, which is mostly caused by the activation of opioid receptors.
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Affiliation(s)
- Hend Omara-Reda
- Université Clermont Auvergne, CNRS, Clermont Auvergne INP, Institut Pascal, TGI, 63000 Clermont-Ferrand, France
| | - Omar Ouachikh
- Université Clermont Auvergne, CNRS, Clermont Auvergne INP, Institut Pascal, TGI, 63000 Clermont-Ferrand, France
| | - Dhouha Hamdi
- Université Clermont Auvergne, CNRS, Clermont Auvergne INP, Institut Pascal, TGI, 63000 Clermont-Ferrand, France
| | - Mohamed Lashin
- Université Clermont Auvergne, CNRS, Clermont Auvergne INP, Institut Pascal, TGI, 63000 Clermont-Ferrand, France
| | - Aziz Hafidi
- Université Clermont Auvergne, CNRS, Clermont Auvergne INP, Institut Pascal, TGI, 63000 Clermont-Ferrand, France.
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Fei‐Sun Y, Huang M, Qin H, Campos de SouzaHan S, Xue H, Wang Y, Wang Y. Protective effect of isoflurane preconditioning on neurological function in rats with HIE. IBRAIN 2022; 8:500-515. [PMID: 37786586 PMCID: PMC10528772 DOI: 10.1002/ibra.12081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 11/18/2022] [Accepted: 11/18/2022] [Indexed: 10/04/2023]
Abstract
Hypoxic-ischemic encephalopathy (HIE) is an important cause of neonatal death and disability, which can lead to long-term neurological and motor dysfunction. Currently, inhalation anesthetics are widely used in surgery, and some studies have found that isoflurane (ISO) may have a positive effect on neuroprotection. In this paper, we investigated whether ISO pretreatment has a neuroprotective effect on the neurological function of HIE rats. Here, 7-day-old neonatal rats were randomly divided into a sham group, a hypoxic-ischemic (HI) group, and an ISO pretreatment (pretreatment) group. The pretreatment group was pretreated with 2% ISO for 1 h, followed by the HI group to establish an HI animal model. The HI‑induced neurological injury was evaluated by Zea‑Longa scores and triphenyltetrazolium (TTC) staining. Neuronal number and histomorphological changes were observed with Nissl staining and Hematoxylin-eosin (HE) staining. In addition, motor learning memory function was evaluated by the Morris water maze (MWM), the Y-maze, and the rotarod tests. HI induced severe neurological dysfunction, brain infarction, and cell apoptosis as well as obvious neuron loss in neonatal rats. In the MWM, the rats in the pretreatment group showed a decrease in escape latency (p = 0.042), indicating that pretreatment with ISO could improve the learning ability of HI rats. The results of Nissl staining showed that in the HI group, there was an irregular arrangement of neurons and nuclear fixation; however, the cell damage was significantly reduced and the total number of neurons was increased after ISO pretreatment (p < 0.001). In conclusion, ISO pretreatment improved cognitive function and attenuated HI-induced reduction of Nissl-positive cells and spatial memory impairment, suggesting that pretreatment with ISO before HI modeling could reduce neuronal cell death in the hippocampus after HI.
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Affiliation(s)
- Yi Fei‐Sun
- Institute of Neurological Disease, National‐Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China HospitalSichuan UniversityChengduSichuanChina
- Center for Epigenetics and Induced Pluripotent Stem Cells, Kennedy Krieger InstituteJohns Hopkins UniversityBaltimoreUSA
| | - Miao Huang
- Department of AnesthesiologySouthwest Medical UniversityLuzhouSichuanChina
| | - Hao‐Yue Qin
- Department of AnesthesiologySouthwest Medical UniversityLuzhouSichuanChina
| | - Senio Campos de SouzaHan
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical SciencesUniversity of MacauMacau SARChina
| | - Han Xue
- School of Basic Medical SciencesJinzhou Medical UniversityJinzhouLiaoningChina
| | - Yu‐Ying Wang
- School of Basic Medical SciencesJinzhou Medical UniversityJinzhouLiaoningChina
| | - Yi‐Bo Wang
- School of Basic Medical SciencesJinzhou Medical UniversityJinzhouLiaoningChina
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Zahir M, Rashidian A, Hoseini M, Akbarian R, Chamanara M. Pharmacological evidence for the possible involvement of the NMDA receptor pathway in the anticonvulsant effect of tramadol in mice. AIMS Neurosci 2022; 9:444-453. [PMID: 36660072 PMCID: PMC9826747 DOI: 10.3934/neuroscience.2022024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 10/28/2022] [Accepted: 11/05/2022] [Indexed: 11/13/2022] Open
Abstract
Background Previous studies have shown controversial results regarding the pro- or anticonvulsant effects of tramadol. Additionally, the underlying mechanism of seizure induction or alleviation by tramadol has not been fully understood. In the current study, the effects of tramadol on pentylenetetrazole (PTZ)-induced seizure and the possible involvement of the N-methyl-D-aspartate (NMDA) pathway were assessed in mice. Methods Male Naval Medical Research Institute (NMRI) mice were treated with intravenous infusion of PTZ in order to induce clonic seizures and determine seizure threshold. Tramadol was injected intraperitoneally (0.1-150 mg/kg) 30 minutes prior to elicitation of seizures. The possible effects of intraperitoneal injections of NMDA receptor antagonists, ketamine (0.5 mg/kg) and MK-801 (0.5 mg/kg) on the anticonvulsant property of tramadol were investigated subsequently. Results Tramadol (1-100 mg/kg) increased PTZ-induced seizure threshold in a dose-dependent, time-independent manner, with optimal anticonvulsant effect at a dose of 100 mg/kg. Acute administration of either ketamine (0.5 mg/kg) or MK-801 (0.5 mg/kg) potentiated the anticonvulsant effect of a subeffective dose of tramadol (0.3 mg/kg). Conclusion These results suggest a possible role of the NMDA pathway in the anticonvulsant effect of tramadol.
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Affiliation(s)
- Mazyar Zahir
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Amir Rashidian
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran,Experimental Medicine Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohsen Hoseini
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran,Experimental Medicine Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Reyhaneh Akbarian
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohsen Chamanara
- Department of Pharmacology, School of Medicine, Aja University of Medical Sciences, P.O. Box 1411718541, Tehran, Iran,* Correspondence:
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Cheng W, Lam RPK, Chan CK. Factors associated with seizure in tramadol overdose: a 12-year retrospective study in Hong Kong. Clin Toxicol (Phila) 2022; 60:1220-1226. [DOI: 10.1080/15563650.2022.2124919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Wendy Cheng
- Accident & Emergency Department, Queen Elizabeth Hospital, Hospital Authority, Hong Kong, S.A.R, China
| | - Rex Pui Kin Lam
- Department of Emergency Medicine, School of Clinical Medicine, The University of Hong Kong, Hong Kong, S.A.R, China
| | - Chi Keung Chan
- Hong Kong Poison Information Centre, Hospital Authority, Hong Kong, S.A.R, China
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Moradi Jafari A, Hassanpourezatti M. Influence of methadone on the anticonvulsant efficacy of valproate sodium gabapentin against maximal electroshock seizure in mice by regulation of brain MDA TNF-α. Front Neurol 2022; 13:920107. [PMID: 36081867 PMCID: PMC9445582 DOI: 10.3389/fneur.2022.920107] [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: 04/14/2022] [Accepted: 07/26/2022] [Indexed: 11/19/2022] Open
Abstract
Methadone is the most frequently used opioid therapy worldwide, with controversial effects on oxidative stress homeostasis. This study investigated the effects of intraperitoneal (i.p.) co-administration of methadone (0.1, 0.3, 1, and 3 mg/kg) and valproate sodium (300 mg/kg) or gabapentin (50 mg/kg) in the mice maximal electroshock (MES)-induced seizure model. The adverse effect of drugs was assessed using the chimney test. The levels of tumor necrosis factor-alpha (TNF-α) and malondialdehyde (MDA) contents were measured in mice brains after a single seizure. Administration of methadone alone resulted in a significant reduction in the duration of hind limb extension (HLE) than that in the control group. Methadone pretreatment at doses of 0.1 and 0.3 mg/kg i.p. decreased, and at doses of 1 and 3 mg/kg i.p. had an increasing effect on anticonvulsant efficacy of gabapentin. Pretreatment with all doses of methadone significantly decreased the valproate anticonvulsive efficacy. At doses of 1 and 3 mg/kg i.p. methadone per se increased brain MDA levels after MES-induced seizure. Administration of methadone (0.3 mg/kg i.p.) enhanced and at 3 mg/kg decreased gabapentin effect on brain MDA level, but their co-treatment did not lead to further increase in MDA. Methadone at 0.3–3 mg/kg enhanced the effect of sodium valproate on MDA levels in the brain, but at all doses significantly potentiated its effect on brain TNF-α levels. The drugs did not produce any side effects on motor coordination in experimental animals. In conclusion, methadone showed different effects on anticonvulsant actions of gabapentin and valproate through regulation of brain levels of MDA and TNF-α.
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Tse K, Beamer E, Simpson D, Beynon RJ, Sills GJ, Thippeswamy T. The Impacts of Surgery and Intracerebral Electrodes in C57BL/6J Mouse Kainate Model of Epileptogenesis: Seizure Threshold, Proteomics, and Cytokine Profiles. Front Neurol 2021; 12:625017. [PMID: 34322075 PMCID: PMC8312573 DOI: 10.3389/fneur.2021.625017] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 06/07/2021] [Indexed: 01/01/2023] Open
Abstract
Intracranial electroencephalography (EEG) is commonly used to study epileptogenesis and epilepsy in experimental models. Chronic gliosis and neurodegeneration at the injury site are known to be associated with surgically implanted electrodes in both humans and experimental models. Currently, however, there are no reports on the impact of intracerebral electrodes on proteins in the hippocampus and proinflammatory cytokines in the cerebral cortex and plasma in experimental models. We used an unbiased, label-free proteomics approach to identify the altered proteins in the hippocampus, and multiplex assay for cytokines in the cerebral cortex and plasma of C57BL/6J mice following bilateral surgical implantation of electrodes into the cerebral hemispheres. Seven days following surgery, a repeated low dose kainate (KA) regimen was followed to induce status epilepticus (SE). Surgical implantation of electrodes reduced the amount of KA necessary to induce SE by 50%, compared with mice without surgery. Tissues were harvested 7 days post-SE (i.e., 14 days post-surgery) and compared with vehicle-treated mice. Proteomic profiling showed more proteins (103, 6.8% of all proteins identified) with significantly changed expression (p < 0.01) driven by surgery than by KA treatment itself without surgery (27, 1.8% of all proteins identified). Further, electrode implantation approximately doubled the number of KA-induced changes in protein expression (55, 3.6% of all identified proteins). Further analysis revealed that intracerebral electrodes and KA altered the expression of proteins associated with epileptogenesis such as inflammation (C1q system), neurodegeneration (cystatin-C, galectin-1, cathepsin B, heat-shock protein 25), blood–brain barrier dysfunction (fibrinogen-α, serum albumin, α2 macroglobulin), and gliosis (vimentin, GFAP, filamin-A). The multiplex assay revealed a significant increase in key cytokines such as TNFα, IL-1β, IL-4, IL-5, IL-6, IL-10, IL12p70, IFN-γ, and KC/GRO in the cerebral cortex and some in the plasma in the surgery group. Overall, these findings demonstrate that surgical implantation of depth electrodes alters some of the molecules that may have a role in epileptogenesis in experimental models.
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Affiliation(s)
- Karen Tse
- Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom.,Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Edward Beamer
- Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Deborah Simpson
- Centre for Proteome Research, Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Robert J Beynon
- Centre for Proteome Research, Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Graeme J Sills
- Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Thimmasettappa Thippeswamy
- Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
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13
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Valian N, Sorayya M, Asadi S, Sherafati F, Ershad A, Savaheli S, Ahmadiani A. Preconditioning by ultra-low dose of tramadol reduces the severity of tramadol-induced seizure: Contribution of glutamate receptors. Biomed Pharmacother 2021; 133:111031. [PMID: 33249277 DOI: 10.1016/j.biopha.2020.111031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 11/07/2020] [Accepted: 11/15/2020] [Indexed: 12/15/2022] Open
Abstract
Tramadol, a weak agonist of mu-opioid receptors, causes seizure via several mechanisms. Preconditioning has been purposed to reduce the epileptic seizures in animal models of epilepsy. The preconditioning effect of tramadol on seizure is not studied yet. This study was designed to evaluate the preconditioning effect of ultra-low dose of tramadol on the seizures induced by tramadol at high dose. Furthermore, regarding the critical role of glutamate signaling in the pathogenesis of epilepsy, the effect of preconditioning on some glutamate signaling elements was also examined. Male Wistar rats received tramadol (2 mg/kg, i.p) or normal saline (1 mL/kg, i.p) in preconditioning and control groups, respectively. After 4 days, the challenging tramadol dose (150 mg/kg) was injected to all rats. Epileptic behaviors were recorded during 50 min. The expression of Norbin (as a regulator of metabotropic glutamate receptor 5), Calponin3 (as a regulator of excitatory synaptic markers), NR1 (NMDA receptor subunit 1) and GluR1 (AMPA receptor subunit 1) was measured in hippocampus, prefrontal cortex (PFC) and amygdala. Preconditioning decreased the number and duration of tremors and tonic-clonic seizures. Norbin, Calponin3, NR1 and GluR1 expression were decreased in hippocampus, and preconditioning had no effect on them. In contrast, it increased Norbin expression in PFC and amygdala, and attenuated NR1 and GluR1 upregulation following tramadol at high dose. These findings indicated that preconditioning by ultra-low dose of tramadol protected the animals against seizures following high dose of tramadol mediated, at least in part, by Norbin up regulation, and NR1 and GluR1 down regulation.
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Affiliation(s)
- Neda Valian
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Marziyeh Sorayya
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Sareh Asadi
- Neurobiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Fatemeh Sherafati
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Ali Ershad
- Department of Clinical Toxicology, Loghman Hakim Educational Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Sara Savaheli
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Abolhassan Ahmadiani
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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14
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Tan Y, Du RL, Su ZY, Xue LL, Liu J, Zhang BL, Huang SJ, Li LJ, Xi-Yang YB, Xiong LL. Vof-16 knockout improves the recovery from hypoxic-ischemic brain damage of neonatal rats. Brain Res 2020; 1748:147070. [PMID: 32827549 DOI: 10.1016/j.brainres.2020.147070] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 08/16/2020] [Accepted: 08/17/2020] [Indexed: 02/08/2023]
Abstract
Hypoxic-ischemic encephalopathy (HIE) results in high neonatal mortality and severe neurological impairments, and its underlying molecular mechanism underwent extensive investigations. Long non-coding RNA (lncRNA) is considered to be an important regulator on brain development and many neurological diseases. Currently, little is known about the role of Vof-16 (lncRNA) in HIE. We detected the relative expression level of Vof-16 in the cortex and hippocampus of hypoxic-ischemic (HI) models whose successful establishment was verified by TTC staining. Then, Vof-16 knockout rats were generated using the CRISPR/Cas engineering technology to search the specific function of the Vof-16 through a series of behavioral evaluations including Neurological severity scores (NSS), Y-maze test, Morris water maze (MWW) test, open field test, and Rotarod test. The results demonstrated the expression of Vof-16 was substantially up-regulated in the cortex and hippocampus of rats with HI injury. Importantly, Vof-16 knockout facilitated the recovery from long-term HI induced nerve damage and neurobehavioral dysfunctions. In conclusion, this study suggests Vof-16 knockout is a promising treatment target for neonatal HIE.
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Affiliation(s)
- Yaxin Tan
- Institute of Neuroscience, Basic Medical College, Kunming Medical University, Kunming, Yunnan 650500, China; Shijiazhuang Maternity & Child Healthcare Hospital, Shijiazhuang, Hebei Province, China
| | - Ruo-Lan Du
- Institute of Neurological Disease, Department of Anesthesiology, Translational Neuroscience Center, West China Hospital, Sichuan University, China
| | - Zhang-Yu Su
- National Traditional Chinese Medicine Clinical Research Base and Western Medicine Translational Medicine Research Center, Affiliated Traditional Chinese Medicine Hospital, Southwest Medical University, Lu Zhou 646000, China
| | - Lu-Lu Xue
- Institute of Neuroscience, Basic Medical College, Kunming Medical University, Kunming, Yunnan 650500, China
| | - Jia Liu
- Department of Animal Zoology, Kunming Medical University, Kunming, Yunnan Province, China
| | - Bao-Lei Zhang
- Department of Animal Zoology, Kunming Medical University, Kunming, Yunnan Province, China
| | | | - Lin-Jun Li
- Institute of Neuroscience, Basic Medical College, Kunming Medical University, Kunming, Yunnan 650500, China
| | - Yan-Bin Xi-Yang
- Institute of Neuroscience, Basic Medical College, Kunming Medical University, Kunming, Yunnan 650500, China.
| | - Liu-Lin Xiong
- National Traditional Chinese Medicine Clinical Research Base and Western Medicine Translational Medicine Research Center, Affiliated Traditional Chinese Medicine Hospital, Southwest Medical University, Lu Zhou 646000, China; Institute of Neurological Disease, Department of Anesthesiology, Translational Neuroscience Center, West China Hospital, Sichuan University, China; School of Pharmacy and Medical Sciences, Sansom Institute, University of South Australia, Adelaide 5000, South Australia, Australia.
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15
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Ali F, Wijdicks EF. Treatment of Movement Disorder Emergencies in Autoimmune Encephalitis in the Neurosciences ICU. Neurocrit Care 2020; 32:286-294. [PMID: 31732848 DOI: 10.1007/s12028-019-00875-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Immune response against neuronal and glial cell surface and cytosolic antigens is an important cause of encephalitis. It may be triggered by activation of the immune system in response to an infection (para-infectious), cancer (paraneoplastic), or due to a patient's tendency toward autoimmunity. Antibodies directed toward neuronal cell surface antigens are directly pathogenic, whereas antibodies with intracellular targets may become pathogenic if the antigen is transiently exposed to the cell surface or via activation of cytotoxic T cells. Immune-mediated encephalitis is well recognized and may require intensive care due to status epilepticus, need for invasive ventilation, or dysautonomia. Patients with immune-mediated encephalitis may become critically ill and display clinically complex and challenging to treat movement disorders in over 80% of the cases (Zhang et al. in Neurocrit Care 29(2):264-272, 2018). Treatment options include immunotherapy and symptomatic agents affecting dopamine or acetylcholine neurotransmission. There has been no prior published guidance for management of these movement disorders for the intensivist. Herein, we discuss the immune-mediated encephalitis most likely to cause critical illness, clinical features and mechanisms of movement disorders and propose a management algorithm.
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Affiliation(s)
- Farwa Ali
- Department of Neurology, Mayo Clinic Rochester Minnesota, 200 1st ST SW, Rochester, MN, 55905, USA.
| | - Eelco F Wijdicks
- Department of Neurology, Mayo Clinic Rochester Minnesota, 200 1st ST SW, Rochester, MN, 55905, USA
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16
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Nakhaee S, Amirabadizadeh A, Brent J, Miri-Moghaddam E, Foadoddini M, Farrokhfall K, Hosseini M, Abdollahi M, Mehrpour O. Tramadol and the occurrence of seizures: a systematic review and meta-analysis. Crit Rev Toxicol 2020; 49:710-723. [PMID: 31914355 DOI: 10.1080/10408444.2019.1694861] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Introduction: Tramadol is a synthetic opioid which is commonly used around the world to relieve moderate to severe pain. One of the serious possible complications of its use is seizures. The present study aims to investigate and summarize the studies related to tramadol and occurrences of seizures after tramadol use and factors influencing these seizures.Methodology: Our systematic review is compliant with PRISMA guidelines. Two researchers systematically searched PubMed/Medline, Web of Sciences, and Scopus. Cohort, case-control, cross-sectional studies, and clinical trials. The risk of bias was assessed using the Newcastle-Ottawa Scale After article quality assessment, a fixed or random model, as appropriate, was used to pool the results in a meta-analysis. Heterogeneity between the studies was assessed with using I-square and Q-test. Forest plots demonstrating the point and pooled estimates were drawn.Results: A total of 51 articles with total sample size of 101 770 patients were included. The results showed that seizure event rate in the subgroups of tramadol poisoning, therapeutic dosage of tramadol, and tramadol abusers was 38% (95% CI: 27-49%), 3% (95% CI: 2-3%), 37% (95% CI: 12-62%), respectively. Tramadol dose was significantly higher in the patients with seizures than those without (mean differences: 0.82, CI 95%: 0.17-1.46). The odds for occurrence of seizures were significantly associated with male gender (pooled OR: 2.24, CI 95%: 1.80-2.77). Naloxone administration was not associated to the occurrence of seizures (pooled OR: 0.47, 95% CI: 0.15-1.49).Conclusions: Our results demonstrate that the occurrence of seizures in patients exposed to tramadol are dose-dependent and related to male gender, but not related to naloxone administration. Given that, most of the evidence derives from studies utilizing a cross-sectional design, the association of tramadol with seizures should not be considered to be definitively established.
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Affiliation(s)
- Samaneh Nakhaee
- Medical Toxicology and Drug Abuse Research Center (MTDRC), Birjand University of Medical Sciences (BUMS), Birjand, Iran
| | - Alireza Amirabadizadeh
- Medical Toxicology and Drug Abuse Research Center (MTDRC), Birjand University of Medical Sciences (BUMS), Birjand, Iran
| | - Jeffrey Brent
- University of Colorado, School of Medicine, Aurora, CO, USA
| | - Ebrahim Miri-Moghaddam
- Cardiovascular Diseases Research Center, Birjand University of Medical Sciences, Birjand, Iran
| | - Mohsen Foadoddini
- Cardiovascular Diseases Research Center, Birjand University of Medical Sciences, Birjand, Iran
| | - Khadijeh Farrokhfall
- Medical Toxicology and Drug Abuse Research Center (MTDRC), Birjand University of Medical Sciences (BUMS), Birjand, Iran
| | - Mehran Hosseini
- Cellular and Molecular Research Center, Birjand University of Medical Sciences, Birjand, Iran
| | - Mohammad Abdollahi
- Toxicology and Diseases Group, Pharmaceutical Sciences Research Center (PSRC), The Institute of Pharmaceutical Sciences (TIPS), Tehran University of Medical Sciences (TUMS), Tehran, Iran.,Department of Toxicology and Pharmacology, Faculty of Pharmacy, Tehran University of Medical Sciences (TUMS), Tehran, Iran
| | - Omid Mehrpour
- Medical Toxicology and Drug Abuse Research Center (MTDRC), Birjand University of Medical Sciences (BUMS), Birjand, Iran.,Rocky Mountain Poison and Drug Safety, Denver Health, Denver, CO, USA
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17
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Samadi M, Shaki F, Bameri B, Fallah M, Ahangar N, Mohammadi H. Caffeine attenuates seizure and brain mitochondrial disruption induced by Tramadol: the role of adenosinergic pathway. Drug Chem Toxicol 2019; 44:613-619. [PMID: 31368376 DOI: 10.1080/01480545.2019.1643874] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Tramadol (TR) is an analgesic drug used to treat moderate-to-severe pain but it induces seizure even at therapeutic doses. The exact mechanism of TR-inducing seizure is not clear but inhibition of the serotonin, GABA, and nitrous oxide (NOS) pathways are the commonly proposed mechanisms. Adenosinergic system has a crucial function in the modulation of seizure. Also, oxidative damage is an unavoidable effect of the seizure. This study was conducted to evaluate the role of the adenosinergic system on the seizure and oxidative stress biomarkers induced by TR using antagonist of the adenosinergic receptors in the Albino mice. For that purpose, generated clonic seizure, as seizure threshold, was evaluated by TR. Caffeine (CAF; 8 mg/kg, i.p.), a nonselective antagonist of adenosine receptors, was administered 1 hour before the seizure induction. The seizure threshold significantly increased by CAF-treated group when compared to TR group (p < 0.001). Oxidative stress biomarkers such as reactive oxygen species, protein carbonyl content, and lipid peroxidation significantly decreased and glutathione content significantly increased by CAF in brain mitochondria compared to the TR group, whereas oxidative biomarkers significantly increased in the TR group compared to the control group. The results of the present study suggested that the adenosinergic system is involved in seizure induced by TR and meanwhile, inhibition of adenosine receptors can decrease the TR seizure threshold and also decrease the induced oxidative damage in the brain mitochondria.
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Affiliation(s)
- Mahedeh Samadi
- Department of Toxicology and Pharmacology, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran
| | - Fatemeh Shaki
- Department of Toxicology and Pharmacology, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran.,Pharmacutical Science Research Center, Hemoglobinopathy Institute, Mazandaran University of Medical Sciences, Sari, Iran
| | - Behnaz Bameri
- Department of Toxicology and Pharmacology, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran
| | - Marjan Fallah
- Department of Toxicology and Pharmacology, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran
| | - Nematollah Ahangar
- Department of Toxicology and Pharmacology, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran.,Pharmacutical Science Research Center, Hemoglobinopathy Institute, Mazandaran University of Medical Sciences, Sari, Iran
| | - Hamidreza Mohammadi
- Department of Toxicology and Pharmacology, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran.,Pharmacutical Science Research Center, Hemoglobinopathy Institute, Mazandaran University of Medical Sciences, Sari, Iran
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18
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Panahi Y, Saboory E, Roshan-Milani S, Drafshpoor L, Rasmi Y, Rassouli A, Sadeghi-Hashjin G. Acute and chronic effects of morphine on Low-Mg 2+ ACSF-induced epileptiform activity during infancy in mice hippocampal slices. Res Pharm Sci 2019; 14:46-54. [PMID: 30936932 PMCID: PMC6407340 DOI: 10.4103/1735-5362.251852] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Interaction of morphine and seizure is complex. Mouse brain hippocampal slices were used to estimate how acute and chronic morphine treatment alters the low-magnesium artificial cerebrospinal fluid (LM-ACSF)-induced seizure activity. Hippocampal slices were taken from the normal and morphine-treated mice. The normal mice received saline while the other group (morphine-treated mice) received morphine daily for 5 consecutive days. Saline/morphine administration was performed subcutaneously (s.c, 0.1 mL) at postnatal days 14-18. Hippocampal slices of all animals were perfused with LM-ACSF followed by different morphine concentrations (0, 10, 100, and 1000 μM) or naloxone (10 μM). Changes in the spike count were considered as indices for quantifying the seizure activity in the slices. In hippocampus of both groups perfused with 10 or 1000 μM morphine, epileptiform activity was suppressed while it was potentiated at 100 μM morphine. The excitatory effect of morphine at 100 μM was stronger in normal mice (acute exposure) than in dependent mice (chronic exposure). Naloxone suppressed the epileptiform activities in both groups. Suppressive effect of naloxone was more significant in morphine-treated mice than in normal mice. The seizure activity in morphine-dependent mice was more labile than that of normal mice. It can be concluded that morphine had a biphasic effect on LM-ACSF-induced epileptiform activities in both groups. The occurrence of seizure was comparable in acute and chronic exposure of morphine but strength of the effect was considerably robust in normal mice. The down regulation of opioid receptors in chronic exposure is likely to be responsible for these differences.
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Affiliation(s)
- Yousef Panahi
- Department of Pharmacology, Faculty of Veterinary Medicine, University of Tehran, Tehran, I.R. Iran
| | - Ehsan Saboory
- Neurophysiology Research Center, Urmia University of Medical Sciences, Urmia, I.R. Iran
| | - Shiva Roshan-Milani
- Department of physiology, Faculty of Medicine, Urmia University of Medical Sciences, Urmia, I.R. Iran
| | - Leila Drafshpoor
- Neurophysiology Research Center, Urmia University of Medical Sciences, Urmia, I.R. Iran
| | - Yousef Rasmi
- Cellular and Molecular Research Center, Urmia University of Medical Sciences, Urmia, I.R. Iran
| | - Ali Rassouli
- Department of Pharmacology, Faculty of Veterinary Medicine, University of Tehran, Tehran, I.R. Iran
| | - Goudarz Sadeghi-Hashjin
- Department of Pharmacology, Faculty of Veterinary Medicine, University of Tehran, Tehran, I.R. Iran
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19
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Aboulhoda BE, Hassan SS. Effect of prenatal tramadol on postnatal cerebellar development: Role of oxidative stress. J Chem Neuroanat 2018; 94:102-118. [PMID: 30342117 DOI: 10.1016/j.jchemneu.2018.10.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 09/17/2018] [Accepted: 10/11/2018] [Indexed: 12/18/2022]
Abstract
BACKGROUND AND AIM The adverse neurological effects of tramadol have recently raised attention. The literature pertaining to studying postnatal cerebellar changes induced by prenatal tramadol is very scanty, thus the current study has been designed to improve understanding of the cerebellar oxidative stress-related alterations associated with tramadol administration during pregnancy in this critical period of neuronal differentiation and synaptic development, thereby highlighting the importance of controlling prenatal prescription of opioids and optimizing care for opioid-dependent pregnant women and their infants. MATERIAL AND METHODS Twenty pregnant female rats of Sprague Dawley strains were used in the study. Their offspring were divided into two groups: group I (control group) offspring of mothers given saline; group II offspring of mothers given tramadol from the 10th day (D10) of gestation till D21. The pups were sacrificed on the 7th, 14th and 21st postnatal days. Cerebellar specimens were processed for histomorphometric, immunohistochemical and electron microscopic assessment and were evaluated for various oxidative stress parameters. RESULTS Tramadol administration during pregnancy caused profound structural abnormalities on the post-natal cerebellar cortex and was associated with oxidative stress evidenced by elevation of lipid peroxidation products and inhibition of antioxidant enzyme activities.
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Affiliation(s)
- Basma Emad Aboulhoda
- Department of Anatomy and Embryology, Faculty of Medicine, Cairo University, Egypt.
| | - Sherif S Hassan
- Department of Anatomy and Embryology, Faculty of Medicine, Cairo University, Egypt; Department of Medical Education, California University of Sciences and Medicine, School of medicine, San Bernardino, 92408 CA, USA
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20
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Panahi Y, Saboory E, Rassouli A, Sadeghi‐Hashjin G, Roshan‐Milani S, Derafshpour L, Rasmi Y. The effect of selective opioid receptor agonists and antagonists on epileptiform activity in morphine‐dependent infant mice hippocampal slices. Int J Dev Neurosci 2017; 60:56-62. [DOI: 10.1016/j.ijdevneu.2017.04.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Revised: 04/01/2017] [Accepted: 04/24/2017] [Indexed: 01/13/2023] Open
Affiliation(s)
- Yousef Panahi
- Department of Pharmacology, Faculty of Veterinary MedicineUniversity of TehranTehranIran
| | - Ehsan Saboory
- Neurophysiology Research Center, Urmia University of Medical SciencesUrmiaIran
| | - Ali Rassouli
- Department of Pharmacology, Faculty of Veterinary MedicineUniversity of TehranTehranIran
| | | | - Shiva Roshan‐Milani
- Department of Physiology, Faculty of MedicineUrmia University of Medical SciencesUrmiaIran
| | - Leila Derafshpour
- Neurophysiology Research Center, Urmia University of Medical SciencesUrmiaIran
| | - Yousef Rasmi
- Cellular and Molecular Research Center, Urmia University of Medical SciencesUrmiaIran
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21
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Khedr EM, Gabra RH, Noaman M, Abo Elfetoh N, Farghaly HSM. Cortical excitability in tramadol dependent patients: A transcranial magnetic stimulation study. Drug Alcohol Depend 2016; 169:110-116. [PMID: 27810653 DOI: 10.1016/j.drugalcdep.2016.09.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Revised: 09/04/2016] [Accepted: 09/20/2016] [Indexed: 12/01/2022]
Abstract
BACKGROUND Addiction to tramadol, a widely used analgesic, is becoming increasingly common. Tramadol can also induce seizures even after a single clinical dose. We tested whether the epileptogenicity of tramadol was associated with any changes in cortical excitability and inhibitory transmission using transcranial magnetic stimulation (TMS). METHODS The study included 16 tramadol dependent patients and 15 age and sex matched healthy volunteers. Clinical evaluation was conducted using an addiction severity index. TMS assessment of excitability was conducted on the motor cortex since the response to each TMS pulse at that site is easily measured in terms of the amplitude of the twitches it evokes in contralateral muscles. Measures included resting and active motor threshold (RMT and AMT respectively), motor evoked potential (MEP) amplitude, cortical silent period (CSP) duration, transcallosal inhibition (TCI), and short interval intracortical inhibition and facilitation (SICI and ICF respectively). Urinary level of tramadol was measured immediately before assessing cortical excitability in each patient. RESULTS RMT and AMT were significantly lower, the duration of the CSP was shorter and SICI was reduced in patients compared with the control group. These findings are suggestive of increased neural excitability and reduced GABAergic inhibition following exposure to tramadol. Also there were negative correlations between the severity of tramadol dependence and a number of cortical excitability parameters (AMT, RMT, and CSP with P=0.002, 0.005, and 0.04 respectively). CONCLUSIONS The results provide evidence for hyperexcitability of the motor cortex coupled with inhibitory deficits in tramadol dependent patients.
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Affiliation(s)
- Eman M Khedr
- Neuropsychiatry Department, Assiut University Hospital, Assiut, Egypt.
| | - Romany H Gabra
- Neuropsychiatry Department, Assiut University Hospital, Assiut, Egypt
| | - Mostafa Noaman
- Neuropsychiatry Department, Assiut University Hospital, Assiut, Egypt
| | - Noha Abo Elfetoh
- Neuropsychiatry Department, Assiut University Hospital, Assiut, Egypt
| | - Hanan S M Farghaly
- Pharmacology Department, Faculty of Medicine, Assiut University, Assiut, Egypt
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22
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Lagard C, Chevillard L, Malissin I, Risède P, Callebert J, Labat L, Launay JM, Laplanche JL, Mégarbane B. Mechanisms of tramadol-related neurotoxicity in the rat: Does diazepam/tramadol combination play a worsening role in overdose? Toxicol Appl Pharmacol 2016; 310:108-119. [PMID: 27641627 DOI: 10.1016/j.taap.2016.09.013] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 08/30/2016] [Accepted: 09/14/2016] [Indexed: 11/29/2022]
Abstract
Poisoning with opioid analgesics including tramadol represents a challenge. Tramadol may induce respiratory depression, seizures and serotonin syndrome, possibly worsened when in combination to benzodiazepines. Our objectives were to investigate tramadol-related neurotoxicity, consequences of diazepam/tramadol combination, and mechanisms of drug-drug interactions in rats. Median lethal-doses were determined using Dixon-Bruce's up-and-down method. Sedation, seizures, electroencephalography and plethysmography parameters were studied. Concentrations of tramadol and its metabolites were measured using liquid-chromatography-high-resolution-mass-spectrometry. Plasma, platelet and brain monoamines were measured using liquid-chromatography coupled to fluorimetry. Median lethal-doses of tramadol and diazepam/tramadol combination did not significantly differ, although time-to-death was longer with combination (P=0.04). Tramadol induced dose-dependent sedation (P<0.05), early-onset seizures (P<0.001) and increase in inspiratory (P<0.01) and expiratory times (P<0.05). The diazepam/tramadol combination abolished seizures but significantly enhanced sedation (P<0.01) and respiratory depression (P<0.05) by reducing tidal volume (P<0.05) in addition to tramadol-related increase in respiratory times, suggesting a pharmacodynamic mechanism of interaction. Plasma M1 and M5 metabolites were mildly increased, contributing additionally to tramadol-related respiratory depression. Tramadol-induced early-onset increase in brain concentrations of serotonin and norepinephrine was not significantly altered by the diazepam/tramadol combination. Interestingly neither pretreatment with cyproheptadine (a serotonin-receptor antagonist) nor a benserazide/5-hydroxytryptophane combination (enhancing brain serotonin) reduced tramadol-induced seizures. Our study shows that diazepam/tramadol combination does not worsen tramadol-induced fatality risk but alters its toxicity pattern with enhanced respiratory depression but abolished seizures. Drug-drug interaction is mainly pharmacodynamic but increased plasma M1 and M5 metabolites may also contribute to enhancing respiratory depression. Tramadol-induced seizures are independent of brain serotonin.
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Affiliation(s)
- Camille Lagard
- Inserm, U1144, Paris, France; UMR-S 1144, Paris-Descartes University, Paris, France; UMR-S 1144, Paris-Diderot University, Paris, France.
| | - Lucie Chevillard
- Inserm, U1144, Paris, France; UMR-S 1144, Paris-Descartes University, Paris, France; UMR-S 1144, Paris-Diderot University, Paris, France.
| | - Isabelle Malissin
- Assistance Publique - Hôpitaux de Paris, Lariboisière Hospital, Department of Medical and Toxicological Critical Care, Paris, France.
| | - Patricia Risède
- Inserm, U1144, Paris, France; UMR-S 1144, Paris-Descartes University, Paris, France; UMR-S 1144, Paris-Diderot University, Paris, France.
| | - Jacques Callebert
- Inserm, U1144, Paris, France; UMR-S 1144, Paris-Descartes University, Paris, France; UMR-S 1144, Paris-Diderot University, Paris, France; Assistance Publique - Hôpitaux de Paris, Lariboisière Hospital, Laboratory of Biochemistry and Molecular Biology, Paris, France.
| | - Laurence Labat
- Inserm, U1144, Paris, France; UMR-S 1144, Paris-Descartes University, Paris, France; UMR-S 1144, Paris-Diderot University, Paris, France; Assistance Publique - Hôpitaux de Paris, Cochin Hospital, Laboratory of Toxicology, Paris, France.
| | - Jean-Marie Launay
- Assistance Publique - Hôpitaux de Paris, Lariboisière Hospital, Laboratory of Biochemistry and Molecular Biology, Paris, France; Inserm, U942, Paris, France.
| | - Jean-Louis Laplanche
- Inserm, U1144, Paris, France; UMR-S 1144, Paris-Descartes University, Paris, France; UMR-S 1144, Paris-Diderot University, Paris, France; Assistance Publique - Hôpitaux de Paris, Lariboisière Hospital, Laboratory of Biochemistry and Molecular Biology, Paris, France.
| | - Bruno Mégarbane
- Inserm, U1144, Paris, France; UMR-S 1144, Paris-Descartes University, Paris, France; UMR-S 1144, Paris-Diderot University, Paris, France; Assistance Publique - Hôpitaux de Paris, Lariboisière Hospital, Department of Medical and Toxicological Critical Care, Paris, France.
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Beyaz SG, Sonbahar T, Bayar F, Erdem AF. Seizures associated with low-dose tramadol for chronic pain treatment. Anesth Essays Res 2016; 10:376-8. [PMID: 27212778 PMCID: PMC4864678 DOI: 10.4103/0259-1162.177181] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The management of cancer pain still poses a major challenge for clinicians. Tramadol is a centrally acting synthetic opioid analgesic. Its well-known side effects include nausea, vomiting, and dizziness; seizures are a rare side effect. Some reports have found that tramadol triggers seizure activity at high doses, whereas a few preclinical studies have found that this seizure activity is not dose-related. We herein present a case involving a patient with laryngeal cancer who developed seizures while on low-dose oral tramadol.
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Affiliation(s)
- Serbülent Gökhan Beyaz
- Department of Anesthesiology and Pain Medicine, Faculty of Medicine, Sakarya University, Sakarya, Turkey
| | - Tuğba Sonbahar
- Department of Anesthesiology, Sakarya University Training and Research Hospital, Sakarya, Turkey
| | - Fikret Bayar
- Department of Anesthesiology, Sakarya University Training and Research Hospital, Sakarya, Turkey
| | - Ali Fuat Erdem
- Department of Anesthesiology and Pain Medicine, Faculty of Medicine, Sakarya University, Sakarya, Turkey
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Rizk MMM, Kamal AM, Bakheet MAA, Abdelfadeel NAM, Hassan EM, Khafagi ATM. Frequency and Factors Associated With Occurrence of Seizures in Patients With Tramadol Abuse. ADDICTIVE DISORDERS & THEIR TREATMENT 2016. [DOI: 10.1097/adt.0000000000000071] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Tsutaoka BT, Ho RY, Fung SM, Kearney TE. Comparative Toxicity of Tapentadol and Tramadol Utilizing Data Reported to the National Poison Data System. Ann Pharmacother 2015; 49:1311-6. [DOI: 10.1177/1060028015604631] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Background: Tapentadol (TAP) and tramadol (TRA) provide pain relief through similar monoaminergic and opioid agonist properties. Objective: To compare clinical effects and medical outcomes between TAP and TRA exposures reported to the National Poison Data System of the American Association of Poison Control Centers. Methods: A retrospective cohort study was conducted analyzing national data for single medication TAP or TRA cases reported from June 2009 through December 2011. Case outcomes, dichotomized as severe versus mild; clinical effects; and use of naloxone were compared. Results: There were 217 TAP and 8566 TRA cases. Significantly more severe outcomes were associated with TAP exposures for an all-age comparison (relative risk [RR] = 1.24; 95% CI = 1.04-1.48), and for the <6-year-old age group (RR = 5.76; 95% CI = 2.20-15.11). Patients with TAP exposures had significantly greater risk of respiratory depression (RR = 5.56; 95% CI = 3.50-8.81), coma (RR = 4.16; 95% CI = 2.33-7.42), drowsiness/lethargy (RR = 1.38; 95% CI = 1.15-1.66), slurred speech (RR = 3.51; 95% CI = 1.98-6.23), hallucination/delusion (RR = 7.25; 95% CI = 3.61-14.57), confusion (RR = 2.54; 95% CI = 1.56-4.13) and use of naloxone (RR = 3.80; 95% CI = 2.96-4.88). TRA exposures had significantly greater risk of seizures (RR = 7.94; 95% CI = 2.99-20.91) and vomiting (RR = 1.96; 95% CI = 1.07-3.60). Conclusion: TAP was associated with significantly more toxic clinical effects and severe outcomes consistent with an opioid agonist. TRA was associated with significantly higher rates of seizures and vomiting.
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Affiliation(s)
- Ben T. Tsutaoka
- California Poison Control System, University of California San Francisco, San Francisco, CA, USA
| | - Raymond Y. Ho
- California Poison Control System, University of California San Francisco, San Francisco, CA, USA
| | - Stacey M. Fung
- Medical Communications Genentech, A Member of the Roche Group, South San Francisco, CA, USA
| | - Thomas E. Kearney
- California Poison Control System, University of California San Francisco, San Francisco, CA, USA
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Metea M, Litwak M, Arezzo J. Assessment of seizure risk in pre-clinical studies: Strengths and limitations of the electroencephalogram (EEG). J Pharmacol Toxicol Methods 2015; 75:135-42. [DOI: 10.1016/j.vascn.2015.04.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Revised: 04/12/2015] [Accepted: 04/13/2015] [Indexed: 11/28/2022]
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The Influence of A118G Single Nucleotide Polymorphism of Human Mu Opioid Receptor Gene and the MDR1 Gene in Egyptian Patients With Tramadol-induced Seizure. ADDICTIVE DISORDERS & THEIR TREATMENT 2015. [DOI: 10.1097/adt.0000000000000048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Gholami M, Saboory E, Roshan-Milani S. Proconvulsant effects of tramadol and morphine on pentylenetetrazol-induced seizures in adult rats using different routes of administration. Epilepsy Behav 2014; 36:90-6. [PMID: 24892755 DOI: 10.1016/j.yebeh.2014.05.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 05/06/2014] [Accepted: 05/07/2014] [Indexed: 12/31/2022]
Abstract
Tramadol is frequently used as a pain reliever. However, it has been sometimes noted to have the potential to cause seizures. Because of its dual mechanism of action (both opioid and nonopioid), the adverse effect profile of tramadol can be different in comparison with single-mechanism opioid analgesics, such as morphine. In the present study, the facilitatory effects of tramadol and morphine on pentylenetetrazol-induced seizures using different routes of administration were compared in rats. Adult female rats were divided into six groups and continuously received saline, morphine, or tramadol on a daily basis for 15 days [gavage (PO) or intraperitoneal (IP)]. An increasing dose of morphine and tramadol was used to prevent resistance to repetitive dose (20-125 mg/kg). Following one week of withdrawal period and 30 min before the seizure induction (PTZ=80 mg/kg, IP), each group of rats was further divided into subgroups that received saline, morphine, or tramadol for the second time on the 22nd day of the experiment. Results showed that, while morphine, tramadol, and their administration had different effects on seizure behaviors, both acute and chronic administrations of morphine and tramadol potentiated PTZ-induced seizures. However, there was no significant difference between morphine and tramadol in terms of seizure severity. Effects of morphine and tramadol on PTZ-induced seizures were also stable following one week of withdrawal. In conclusion, this study indicated similar severity in the proconvulsant effect of morphine and tramadol on PTZ-induced seizures, which might depend on their similar effects on GABAergic pathways.
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Affiliation(s)
- Morteza Gholami
- Department of Biology, Faculty of Sciences, University of Urmia, Iran.
| | - Ehsan Saboory
- Neurophysiology Research Center, Urmia University of Medical Sciences, Iran.
| | - Shiva Roshan-Milani
- Department of Physiology, Faculty of Medicine, Urmia University of Medical Sciences, Iran.
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Arjunan V, Santhanam R, Marchewka MK, Mohan S. Comprehensive quantum chemical and spectroscopic (FTIR, FT-Raman, 1H, 13C NMR) investigations of O-desmethyltramadol hydrochloride an active metabolite in tramadol--an analgesic drug. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 122:315-330. [PMID: 24316546 DOI: 10.1016/j.saa.2013.11.040] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 11/06/2013] [Accepted: 11/08/2013] [Indexed: 06/02/2023]
Abstract
O-desmethyltramadol is one of the main metabolites of tramadol widely used clinically and has analgesic activity. The FTIR and FT-Raman spectra of O-desmethyl tramadol hydrochloride are recorded in the solid phase in the regions 4000-400 cm(-1) and 4000-100 cm(-1), respectively. The observed fundamentals are assigned to different normal modes of vibration. Theoretical studies have been performed as its hydrochloride salt. The structure of the compound has been optimised with B3LYP method using 6-31G(**) and cc-pVDZ basis sets. The optimised bond length and bond angles are correlated with the X-ray data. The experimental wavenumbers were compared with the scaled vibrational frequencies determined by DFT methods. The IR and Raman intensities are determined with B3LYP method using cc-pVDZ and 6-31G(d,p) basic sets. The total electron density and molecular electrostatic potential surfaces of the molecule are constructed by using B3LYP/cc-pVDZ method to display electrostatic potential (electron+nuclei) distribution. The electronic properties HOMO and LUMO energies were measured. Natural bond orbital analysis of O-desmethyltramadol hydrochloride has been performed to indicate the presence of intramolecular charge transfer. The (1)H and (13)C NMR chemical shifts of the molecule have been anlysed.
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Affiliation(s)
- V Arjunan
- Department of Chemistry, Kanchi Mamunivar Centre for Post-Graduate Studies, Puducherry 605 008, India.
| | - R Santhanam
- Research and Development Centre, Bharathiar University, Coimbatore 641 046, India
| | - M K Marchewka
- Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw 2, Poland
| | - S Mohan
- School of Sciences and Humanities, Vel Tech University, Avadi, Chennai 600 062, India
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Rogers E, Mehta S, Shengelia R, Reid MC. Four Strategies for Managing Opioid-Induced Side Effects in Older Adults. CLINICAL GERIATRICS 2013; 21:http://www.consultant360.com/articles/four-strategies-managing-opioid-induced-side-effects-older-adults. [PMID: 25949094 PMCID: PMC4418642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Affiliation(s)
| | - Sonal Mehta
- Department of Medicine, Division of Geriatrics and Gerontology, Weill Cornell Medical College, New York, NY
| | - Rose Shengelia
- Department of Medicine, Division of Geriatrics and Gerontology, Weill Cornell Medical College, New York, NY
| | - Manney Carrington Reid
- Department of Medicine, Division of Geriatrics and Gerontology, Weill Cornell Medical College, New York, NY
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Elander M. Drug-Induced Convulsions in Nonclinical Safety Studies: Implication for Clinical Development. Drug Dev Res 2013. [DOI: 10.1002/ddr.21061] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Mikael Elander
- Department of Regulatory Toxicology & Safety Assessment; H. Lundbeck A/S; Valby; Copenhagen; Denmark
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Cicero TJ, Ellis MS. Health outcomes in patients using no-prescription online pharmacies to purchase prescription drugs. J Med Internet Res 2012; 14:e174. [PMID: 23220405 PMCID: PMC3799543 DOI: 10.2196/jmir.2236] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 08/07/2012] [Accepted: 09/07/2012] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Many prescription drugs are freely available for purchase on the Internet without a legitimate prescription from a physician. OBJECTIVE This study focused on the motivations for using no-prescription online pharmacies (NPOPs) to purchase prescription drugs rather than using the traditional doctor-patient-pharmacy model. We also studied whether users of NPOP-purchased drugs had poorer health outcomes than those who obtain the same drug through legitimate health care channels. METHODS We selected tramadol as a representative drug to address our objective because it is widely prescribed as an unscheduled opioid analgesic and can easily be purchased from NPOPs. Using search engine marketing (SEM), we placed advertisements on search result pages stemming from the keyword "tramadol" and related terms and phrases. Participants, who either used the traditional doctor-patient-pharmacy model to obtain tramadol (traditional users, n = 349) or purchased it on the Web without a prescription from their local doctor (ie, nontraditional users, n = 96), were then asked to complete an online survey. RESULTS Respondents in both groups were primarily white, female, and in their mid-forties (nontraditional users) to upper forties (traditional users). Nearly all nontraditional users indicated that their tramadol use was motivated by a need to treat pain (95%, 91/96) that they perceived was not managed appropriately through legitimate health care channels. A majority of nontraditional users (55%, 41/75) indicated they used NPOPs because they did not have access to sufficient doses of tramadol to relieve pain. In addition, 29% (22/75) of nontraditional users indicated that the NPOPs were a far cheaper alternative than seeing a physician, paying for an office visit, and filling a prescription at a local pharmacy, which is often at noninsured rates for those who lack medical insurance (37%, 35/96, of NPOP users). The remainder of participants (16%, 12/96) cited other motivations (eg, anonymity) for using NPOPs. In terms of health outcomes, nontraditional users experienced a significantly (P < .01) greater number and severity of adverse events, including life-threatening seizures: 7% (7/96) of nontraditional users reported seizures, while none of the traditional users reported seizures. CONCLUSIONS Although online pharmacies can offer distinct advantages in terms of convenience and cost, users of these "rogue" pharmacies that offer drugs with no prescription or doctor supervision do so at great risk to their health, as evidenced by much higher rates of adverse events. The most logical explanation for these findings is that the lack of physician oversight of dosage schedules, contraindicated conditions, and concomitant medications, were responsible for the increased intensity and frequency of adverse events in the nontraditional users. Although we only examined tramadol, it is logical to postulate that similar results would be observed with dozens of equally accessible prescription drugs. As such, the geometric growth in the use of online pharmacies around the world should prompt intense medical and regulatory discussion about their role in the provision of medical care.
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Affiliation(s)
- Theodore J Cicero
- School of Medicine, Department of Psychiatry, Washington University in St. Louis, Saint Louis, MO 63110, USA.
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Raiger LK, Naithani U, Bhatia S, Chauhan SS. Seizures after intravenous tramadol given as premedication. Indian J Anaesth 2012; 56:55-7. [PMID: 22529421 PMCID: PMC3327072 DOI: 10.4103/0019-5049.93345] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A 35-year-old, 50-kg female with a history of epilepsy was scheduled for elective breast surgery (fibroadenoma) under general anaesthesia. She was given glycopyrrolate 0.2 mg, ondansetron 4 mg and tramadol 100 mg i.v. as premedication. Within 5 min, she had an acute episode of generalised tonic–clonic seizure that was successfully treated with 75 mg thiopentone i.v. and after 30 min, she was given general anaesthesia with endotracheal intubation. Surgery, intra-operative period, extubation and post-operative period were uneventful. We conclude that tramadol may provoke seizures in patients with epilepsy even within the recommended dose range.
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Affiliation(s)
- Lalit Kumar Raiger
- Department of Anaesthesiology and Critical Care, RNT Medical College and Associated Group of Hospitals, Udaipur, Rajasthan, India
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Bankstahl M, Bankstahl JP, Bloms-Funke P, Löscher W. Striking differences in proconvulsant-induced alterations of seizure threshold in two rat models. Neurotoxicology 2011; 33:127-37. [PMID: 22209701 DOI: 10.1016/j.neuro.2011.12.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Revised: 11/24/2011] [Accepted: 12/12/2011] [Indexed: 11/28/2022]
Abstract
During drug development, seizure threshold tests are widely used to identify potential proconvulsant activity of investigational drugs. The most commonly used tests in this respect are the timed intravenous pentylenetetrazole (PTZ) infusion seizure test and the maximal electroshock seizure threshold (MEST) test in mice or rats. To our knowledge, no study is available in which proconvulsant drug activities in these models are directly compared, which prompted us to perform such experiments in male Wistar rats. Five drugs with reported proconvulsant activity were tested in the two models: d-amphetamine, chlorpromazine, caffeine, theophylline, and tramadol. Furthermore, the anticonvulsant drug phenobarbital was included in the experiments. While phenobarbital exerted anticonvulsant activity in both models, the five proconvulsant drugs markedly differed in their effects. In the dose range tested, d-amphetamine significantly lowered the PTZ seizure threshold but increased the MEST, caffeine and theophylline did not alter the PTZ seizure threshold but decreased the MEST, and tramadol reduced the PTZ threshold but increased the MEST. These marked differences between seizure threshold tests are most likely a consequence of the mechanisms underlying seizure induction in these tests. Our data indicate that using only one seizure threshold model during preclinical drug development may pose the risk that potential proconvulsant activity of an investigational drug is overseen. However, the label "proconvulsant" may be misleading if such activity only occurs at doses high above the therapeutic range, but the drug is not proconvulsant or even exerts anticonvulsant effects at lower, therapeutically relevant doses.
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Affiliation(s)
- Marion Bankstahl
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine Hannover, Hannover, Germany
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Sauriyal DS, Jaggi AS, Singh N. Extending pharmacological spectrum of opioids beyond analgesia: multifunctional aspects in different pathophysiological states. Neuropeptides 2011; 45:175-88. [PMID: 21208657 DOI: 10.1016/j.npep.2010.12.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Revised: 12/06/2010] [Accepted: 12/07/2010] [Indexed: 11/29/2022]
Abstract
Opioids are well known to exert potent central analgesic actions. In recent years, the numerous studies have unfolded the critical role of opioids in the pathophysiology of various diseases as well as in biological phenomenon of therapeutic interest. The endogenous ligands of opioid receptors are derived from three independent genes and their appropriate processing yields the major representative opioid peptides beta-endorphin, met-enkephalin, leu-enkephalin and dynorphin, respectively. These peptides and their derivatives exhibit different affinity and selectivity for the mu-, delta- and kappa-receptors located on the central and the peripheral neurons, neuroendocrine, immune, and mucosal cells and on many other organ systems. The present review article highlights the role of these peptides in central nervous system disorders such as depression, anxiety, epilepsy, and stress; gastrointestinal disorders such as diarrhea, postoperative ileus, ulceration, and irritable bowel syndrome; immune system and related inflammatory disorders such as osteoarthritis and rheumatoid arthritis; and others including respiratory, alcoholism and obesity/binge eating. Furthermore, the key role of opioids in different forms of pre- and post-conditioning including ischemic and pharmacological along with in remote preconditioning has also been described.
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Yarkan Uysal H, Bilimgut B, Dikmen B, Inan N, Ulger G, Eruyar S. Epileptic seizure following IV tramadol in a patient with mental retardation and cerebellar ataxia. PAIN MEDICINE 2011; 12:833-6. [PMID: 21463462 DOI: 10.1111/j.1526-4637.2011.01079.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To present a case of an epileptic seizure related to intravenous (IV) tramadol for pain control following a total abdominal hysterectomy operation on a patient with mental retardation and cerebellar ataxia. BACKGROUND Tramadol is an analgesic with a dual mechanism of action and has several side effects, one of which is epileptic seizure. CASE REPORT A 42-year-old female with mental retardation and cerebellar ataxia presented with an epileptic seizure after administration of IV tramadol for postoperative pain. Magnetic resonance imaging scans were normal, but laboratory tests showed hypocalcemia. Next, calcium replacement was administered. Postoperative pain treatment with tramadol was discontinued because tramadol was felt to be a possible cause of the seizure observed in this patient. In order to treat the epileptic seizure, IV phenytoin sodium infusion was started. On the second postoperative day, calcium levels were found to be normal, and the IV antiepileptic medication was changed to an oral form. The patient had no subsequent seizures during the clinical follow-up. She was discharged on the fourth postoperative day without any other complications. CONCLUSION Even in recommended doses, IV tramadol may cause epileptic seizures on predisposed patients.
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Affiliation(s)
- Hale Yarkan Uysal
- Ministry of Health, Ankara Training and Research Hospital, II. Anesthesiology and Reanimation Clinic, Ankara, Turkey.
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Lesani A, Javadi-Paydar M, Khodadad TK, Asghari-Roodsari A, Shirkhodaei M, Norouzi A, Dehpour AR. Involvement of the nitric oxide pathway in the anticonvulsant effect of tramadol on pentylenetetrazole-induced seizures in mice. Epilepsy Behav 2010; 19:290-5. [PMID: 20880756 DOI: 10.1016/j.yebeh.2010.08.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 08/03/2010] [Accepted: 08/05/2010] [Indexed: 10/19/2022]
Abstract
In the present study, the effects of tramadol on pentylenetetrazole (PTZ)-induced seizures and involvement of nitric oxide (NO) were assessed in mice. To determine the threshold for clonic seizures, PTZ was administered intravenously. Tramadol was administered intraperitoneally (0.5-50mg/kg) 30 minutes prior to induction of seizures. The effects of the nitric oxide synthase (NOS) inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME; 0.5, 1, 5, and 10mg/kg), the nitric oxide precursor L-arginine (10, 30, and 60 mg/kg), and the nonspecific opioid receptor antagonist naloxone (0.1, 0.5, 1, and 5mg/kg) on the anticonvulsant effect of tramadol were investigated. Administration of tramadol (1mg/kg) increased the threshold for seizures induced with PTZ in a monophasic, dose-independent, and time-dependent manner. Acute administration of L-NAME (5 and 10mg/kg) inhibited the anticonvulsant effect of tramadol (1mg/kg), whereas L-arginine, in the noneffective dose range (30 and 60 mg/kg), potentiated the seizure threshold when co-administered with a subeffective dose of tramadol (0.5mg/kg). Naloxone partially and dose-independently antagonized the anticonvulsant effect of tramadol (1mg/kg). These results indicate that the anticonvulsant effect of tramadol is mediated by the nitric oxide pathway and also by classic opioid receptors.
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Affiliation(s)
- Ali Lesani
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
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Márquez-Romero J, Zermeño-Pohls F, Soto-Cabrera E. Crisis epiléptica convulsiva relacionada con sobredosis de tramadol. Neurologia 2010; 25:583-5. [DOI: 10.1016/j.nrl.2009.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 07/08/2009] [Indexed: 12/01/2022] Open
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Fischborn SV, Soerensen J, Potschka H. Targeting the prostaglandin E2 EP1 receptor and cyclooxygenase-2 in the amygdala kindling model in mice. Epilepsy Res 2010; 91:57-65. [DOI: 10.1016/j.eplepsyres.2010.06.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 06/18/2010] [Accepted: 06/23/2010] [Indexed: 02/05/2023]
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Jang HS, Jang IS, Lee MG. The effects of tramadol on electroencephalographic spectral parameters and analgesia in rats. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2010; 14:191-8. [PMID: 20631893 DOI: 10.4196/kjpp.2010.14.3.191] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Revised: 06/10/2010] [Accepted: 06/20/2010] [Indexed: 11/15/2022]
Abstract
The effects of different doses of tramadol on analgesia and electroencephalographic (EEG) spectral parameters were compared in rats. Saline or tramadol 5, 10, 20 or 40 mg/kg was administered. The degree of analgesia was evaluated by tail-flick latency, and the degree of seizure was measured using numerical seizure score (NSS). Additionally, band powers, median power frequency and spectral edge frequency 95 were measured to quantify the EEG response. All doses of tramadol produced spike-wave discharge. Tramadol significantly and dose-dependently increased the analgesia, but these effects did not correspond with the changes in the EEG spectral parameters. NSS significantly increased in the Tramadol 20 and 40 mg/kg treatment groups compared to the Control and TRA5 groups, and two rats given 40 mg/kg had convulsions. In conclusion, tramadol dose-dependently increased the analgesic effect, and the 10 mg/kg dose appears to be a reliable clinical dose for analgesia in rats, but dose-dependent increases in analgesia and seizure severity did not correlate with EEG spectral parameters.
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Affiliation(s)
- Hwan-Soo Jang
- Department of Pharmacology, School of Medicine, Kyungpook National University, Daegu 700-422, Korea
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Gosch M, Böhmdorfer B, Benvenuti-Falger U, Dovjak P, Iglseder B, Lechleitner M, Otto R, Roller RE, Sommeregger U. Polypharmazie und Schmerztherapie. Wien Med Wochenschr 2010; 160:286-292. [DOI: 10.1007/s10354-010-0788-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Márquez-Romero J, Zermeño-Pohls F, Soto-Cabrera E. Convulsive status epilepticus associated with a tramadol overdose. NEUROLOGÍA (ENGLISH EDITION) 2010. [DOI: 10.1016/s2173-5808(20)70107-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Tramadol-induced seizurogenic effect: a possible role of opioid-dependent histamine H1 receptor activation-linked mechanism. Naunyn Schmiedebergs Arch Pharmacol 2009; 381:11-9. [PMID: 20012267 DOI: 10.1007/s00210-009-0476-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Accepted: 11/13/2009] [Indexed: 12/17/2022]
Abstract
The present study has been designed to investigate the role of opioid receptors, mast cells, and histamine receptors (H(1) subtype) in the seizurogenic effect of tramadol on pentylenetetrazole-treated mice. A single injection of pentylenetetrazole (80 mg kg(-1)) was used to elicit seizure activity in mice. Seizures were assessed in terms of the time latency of the onset of Straub-like tail, onset of jerky movements of whole body, convulsions, and death. Tramadol administration (50 mg kg (-1)) caused a marked increase in seizurogenic activity of pentylenetetrazole as measured in terms of a significant decrease in the time latency of the onset of Straub-like tail, jerky movements of whole body, convulsions, and death. Moreover, prior administration of naloxone (2 mg kg(-1)), fexofenadine (100 mg kg(-1)), cetrizine, sodium cromoglycate, and ketotifen (10 mg kg(-1)), respectively, attenuated the seizurogenic activity that tramadol exerted on pentylenetetrazole-treated mice. Therefore, it may be suggested that tramadol exerts a seizurogenic effect on mice via an H(1) receptor activation-linked pathway possibly through an opioid receptor-dependent release of histamine from the mast cells.
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Preclinical assessment of proconvulsant drug activity and its relevance for predicting adverse events in humans. Eur J Pharmacol 2009; 610:1-11. [DOI: 10.1016/j.ejphar.2009.03.025] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2009] [Revised: 02/19/2009] [Accepted: 03/03/2009] [Indexed: 12/20/2022]
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Rehni AK, Singh I, Kumar M. Tramadol-induced seizurogenic effect: a possible role of opioid-dependent gamma-aminobutyric acid inhibitory pathway. Basic Clin Pharmacol Toxicol 2008; 103:262-6. [PMID: 18684224 DOI: 10.1111/j.1742-7843.2008.00276.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The present study has been designed to pharmacologically investigate the role of opioid and gamma-aminobutyric acid receptors on the seizurogenic effect of tramadol. A single injection of pentylenetetrazole (80 mg/kg) was used to elicit seizure activity in mice. Seizures were assessed in terms of the time latency of the onset of Straub's tail phenomenon, onset of jerky movements of whole body, convulsions and death. Tramadol administration (50 mg/kg) caused a marked increase in seizurogenic activity of pentylenetetrazole as measured in terms of a significant decrease in the time latency of the onset of Straub's tail phenomenon, jerky movements of whole body, convulsions and death. Moreover, prior administration of naloxone (2 mg/kg) and gabapentin (25 mg/kg), respectively, attenuated the seizurogenic activity that tramadol exerted on pentylenetetrazole-treated mice. Furthermore, prior administration of naloxone (2 mg/kg) and gabapentin (25 mg/kg), respectively, also attenuated the seizurogenic activity exerted by tramadol per se. Therefore, it is suggested that tramadol exerts a seizurogenic effect on mice possibly via an opioid-dependent gamma-aminobutyric acid inhibitory pathway.
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Affiliation(s)
- Ashish K Rehni
- Chitkara College of Pharmacy, Chandigarh-Patiala National Highway, Rajpura-140401, Patiala, Punjab, India.
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Abstract
Several studies have demonstrated the impact of CYP2D6 polymorphism on the pharmacokinetics of tramadol. However, the relationship between the O-demethylation of tramadol and O-desmethyltramadol (M1) and CYP2D6 activity has not previously been investigated with tramadol in multimedicated outpatients under steady-state conditions. Hence, the aim of this study was to determine if the well documented pharmacokinetics of tramadol regarding CYP2D6 could be verified in a study including 88 multimedicated Faroese patients, treated with tramadol at steady-state conditions. Further, the study aimed to investigate whether the previously observed frequency of CYP2D6 poor metabolizers (PMs) in the Faroese, which was shown to be double that of other Europeans, was evident in a patient group medicated with a CYP2D6 substrate. The patients were CYP2D6-phenotyped by the intake of sparteine, followed by urine collection over 12 hours. Sparteine and its metabolites were assayed by gas chromatography. Genotype analyses for the CYP2D6 3, 4, 6, and 9 alleles were performed by polymerase chain reaction and Taqman technology. Plasma and urinary concentrations of (+/-)-tramadol and (+/-)-M1 were determined by high-performance liquid chromatography. With use of CYP2D6 phenotyping, 10 patients (11.5% [95% confidence interval (CI), 5.7-20.1%]) were classified as CYP2D6 PMs, and 8 (9.3% [95% CI, 4.1-17.3%]) of these were genotyped as CYP2D6 PMs. The PM frequency was not statistically significantly higher than that in other European populations (7%-10%). The concentrations of (+)-M1 when corrected for dose (nM/mg) and the (+)-M1/(+)-tramadol ratio were approximately 14-fold higher in the extensive metabolizers (EMs) than in the PMs. In conclusion, the impact of the CYP2D6 polymorphism on the pharmacokinetics of tramadol was clearly demonstrated in a group of multimedicated patients treated with tramadol under steady-state conditions. Further, the frequency of PMs was not higher than that in other European populations, as previously shown in different Faroese groups, possibly because of discontinued tramadol treatment in Faroese patients who were PMs.
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Raffa RB, Stone DJ. Unexceptional seizure potential of tramadol or its enantiomers or metabolites in mice. J Pharmacol Exp Ther 2008; 325:500-6. [PMID: 18292293 DOI: 10.1124/jpet.108.137273] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Tramadol is one of the most widely used centrally acting analgesics worldwide. Because of its multimodal analgesic mechanism (opioid plus nonopioid), the adverse effects profile of tramadol, similar to its analgesic profile, can be atypical compared with single-mechanism opioid analgesics. The comparison is often favorable (e.g., less respiratory depression or abuse), but it is sometimes cited as unfavorable in regard to seizure potential. As part of a broader study of this analgesic, we compared seizure induction in mice produced by administration of tramadol, the enantiomers and metabolites [M1 (O-desmethyl tramadol), M2 (N-desmethyl tramadol), M3 (N,N-didesmethyl tramadol), M4 (O,N,N-tridesmethyl tramadol), and M5 (O,N-didesmethyl tramadol)] of tramadol, and opioid and nonopioid reference compounds. We found that tramadol, its enantiomers, and M1 to M5 metabolites were of intermediate potency in this endpoint (on either a milligram per kilogram or millimole per kilogram basis). The SD50 (estimated dose required to induce seizures in 50% of test group) of tramadol to antinociceptive ED50 ratio was almost identical to that of codeine. The enantiomers of tramadol were about equipotent to tramadol on this endpoint. The M1 to M5 metabolites (and M1 enantiomers) of tramadol were less potent than tramadol. The relative potency of tramadol to opioids was not altered by quinidine (an inhibitor of CYP4502D6), noxious stimulus (48 degrees C hot-plate), multiple dosing, or in reserpinized mice. Tramadol seizures were increased by naloxone, principally at high tramadol doses and due to an effect on the (-)enantiomer that overcame the opposite effect on the (+)enantiomer. No synergistic effect on seizure induction was observed between concomitant tramadol and codeine or morphine.
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Affiliation(s)
- Robert B Raffa
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, Pennsylvania, USA.
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Bethmann K, Brandt C, Löscher W. Resistance to phenobarbital extends to phenytoin in a rat model of temporal lobe epilepsy. Epilepsia 2007; 48:816-26. [PMID: 17319923 DOI: 10.1111/j.1528-1167.2007.00980.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE Most patients who are resistant to the first antiepileptic drug (AED) treatment are also resistant to a treatment with a second or third AED, indicating that patients who have an inadequate response to initial treatment with AEDs are likely to have refractory epilepsy. Animal models of refractory epilepsy are important tools to study mechanisms of AED resistance and develop new treatment strategies for counteracting resistance. We have recently described a rat model of temporal lobe epilepsy (TLE), in which spontaneous recurrent seizures (SRS) develop after a status epilepticus induced by sustained electrical stimulation of the basolateral amygdala. Prolonged treatment of epileptic rats with phenobarbital (PB) resulted in two subgroups, PB responders and PB nonresponders. METHODS In the present study we examined if rats with PB-resistant seizures are also resistant to phenytoin (PHT), using continuous EEG/video recording of spontaneous seizures. RESULTS First, a new group of 15 epileptic rats was produced and selected by treatment with PB into responders (8 rats) and nonresponders (6 rats), respectively. During subsequent treatment with PHT, the doses of PHT had to be individually adjusted for each rat to avoid toxicity. Treatment with PHT led to complete seizure control in two animals and a >50% reduction of seizure frequency in three other rats, which were considered PHT responders. In nine of the remaining rats, PHT did not exert any clear anticonvulsant effect, so that these rats were considered nonresponders. Plasma levels of PHT did not differ significantly between responders and nonresponders. When comparing the PB and PHT nonresponder groups, five of the six PB-resistant rats (83%) were also resistant to PHT, demonstrating that rats that have an inadequate response to initial treatment with PB are likely to be also resistant to treatment with a second AED. CONCLUSIONS The AED-resistant rats of our model meet the definition of pharmacoresistance in animal models, that is, persistent seizure activity not responding to at least two AEDs at maximum tolerated doses. This new model of pharmacoresistant TLE may be useful in the targeted development of new therapies for refractory epilepsy.
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Affiliation(s)
- Kerstin Bethmann
- Department of Pharmacology, Toxicology and Pharmacy, University of Veterinary, Medicine, Hannover, Germany
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