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Ikeda A, Tomiyasu M, Yamamoto A, Tsuyusaki Y, Kawai Y, Tanabe M, Tsuji M, Iai M, Aida N, Goto T. Elevation of brain gamma‐aminobutyric acid levels is associated with vigabatrin‐associated brain abnormalities on magnetic resonance imaging. Epilepsy Res 2022; 181:106881. [DOI: 10.1016/j.eplepsyres.2022.106881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 01/14/2022] [Accepted: 02/04/2022] [Indexed: 11/29/2022]
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Eid T. Localizing the Seizure Onset Site Through Metabolic Imaging of GABA. Epilepsy Curr 2021; 21:282-284. [PMID: 34690567 PMCID: PMC8512926 DOI: 10.1177/15357597211011988] [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] [Indexed: 11/30/2022] Open
Abstract
In Vivo Gamma-Aminobutyric Acid Increase as a Biomarker of the Epileptogenic
Zone: An Unbiased Metabolomics Approach Hamelin S, Stupar V, Maziere L, et al. Epilepsia.
2021;62(1):163-175. Objective: Following surgery, focal seizures relapse in 20% to 50% of cases due to the
difficulty of delimiting the epileptogenic zone (EZ) by current imaging or
electrophysiological techniques. Here, we evaluate an unbiased metabolomics approach
based on ex vivo and in vivo nuclear magnetic resonance spectroscopy (MRS) methods
to discriminate the EZ in a mouse model of mesiotemporal lobe epilepsy (MTLE). Methods: Four weeks after unilateral injection of kainic acid (KA) into the dorsal
hippocampus of mice (KA-MTLE model), we analyzed hippocampal and cortical samples
with high-resolution magic angle spinning (HRMAS) MRS. Using advanced multivariate
statistics, we identified the metabolites that best discriminate the injected dorsal
hippocampus (EZ) and developed an in vivo MEGAPRESS MRS method to focus on the
detection of these metabolites in the same mouse model. Results: Multivariate analysis of HRMAS data provided evidence that γ-aminobutyric acid
(GABA) is largely increased in the EZ of KA-MTLE mice and is the metabolite that
best discriminates the EZ when compared with sham and, more importantly, when
compared with adjacent brain regions. These results were confirmed by capillary
electrophoresis analysis and were not reversed by a chronic exposition to an
antiepileptic drug (carbamazepine). Then, using in vivo noninvasive GABA-edited MRS,
we confirmed that a high GABA increase is specific to the injected hippocampus of
KA-MTLE mice. Significance: Our strategy using ex vivo MRS-based untargeted metabolomics to select the most
discriminant metabolite(s), followed by in vivo MRS-based targeted metabolomics, is
an unbiased approach to accurately define the EZ in a mouse model of focal epilepsy.
Results suggest that GABA is a specific biomarker of the EZ in MTLE.
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Prescot AP, Prisciandaro JJ, Miller SR, Ingenito G, Kondo DG, Renshaw PF. Two-Dimensional Proton Magnetic Resonance Spectroscopy versus J-Editing for GABA Quantification in Human Brain: Insights from a GABA-Aminotransferase Inhibitor Study. Sci Rep 2018; 8:13200. [PMID: 30181656 PMCID: PMC6123452 DOI: 10.1038/s41598-018-31591-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 08/22/2018] [Indexed: 11/25/2022] Open
Abstract
Metabolite-specific, scalar spin-spin coupling constant (J)-editing 1H MRS methods have become gold-standard for measuring brain γ-amino butyric acid (GABA) levels in human brain. Localized, two-dimensional (2D) 1H MRS technology offers an attractive alternative as it significantly alleviates the problem of severe metabolite signal overlap associated with standard 1D MRS and retains spectroscopic information for all MRS-detectable species. However, for metabolites found at low concentration, a direct, in vivo, comprehensive methods comparison is challenging and has not been reported to date. Here, we document an assessment of comparability between 2D 1H MRS and J-editing methods for measuring GABA in human brain. This clinical study is unique in that it involved chronic administration a GABA-amino transferase (AT) inhibitor (CPP-115), which induces substantial increases in brain GABA concentration, with normalization after washout. We report a qualitative and quantitative comparison between these two measurement techniques. In general, GABA concentration changes detected using J-editing were closely mirrored by the 2D 1H MRS time courses. The data presented are particularly encouraging considering recent 2D 1H MRS methodological advances are continuing to improve temporal resolution and spatial coverage for achieving whole-brain, multi-metabolite mapping.
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Affiliation(s)
- Andrew P Prescot
- Department of Radiology and Imaging Sciences, University of Utah School of Medicine, Salt Lake City, UT, USA.
| | - James J Prisciandaro
- Department of Psychiatry and Behavioral Sciences, Addiction Sciences Division, Medical University of South Carolina, Charleston, SC, USA
| | | | | | - Douglas G Kondo
- Department of Psychiatry, University of Utah School of Medicine, Salt Lake City, UT, USA.,Rocky Mountain Mental Illness Research, Education, and Clinical Center (MIRECC), Department of Veterans Affairs Medical Center, Salt Lake City, UT, USA
| | - Perry F Renshaw
- Department of Psychiatry, University of Utah School of Medicine, Salt Lake City, UT, USA.,Rocky Mountain Mental Illness Research, Education, and Clinical Center (MIRECC), Department of Veterans Affairs Medical Center, Salt Lake City, UT, USA
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Prescot AP, Miller SR, Ingenito G, Huber RS, Kondo DG, Renshaw PF. In Vivo Detection of CPP-115 Target Engagement in Human Brain. Neuropsychopharmacology 2018; 43:646-654. [PMID: 28741622 PMCID: PMC5770752 DOI: 10.1038/npp.2017.156] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 07/11/2017] [Accepted: 07/17/2017] [Indexed: 11/09/2022]
Abstract
CPP-115, a next-generation γ-amino butyric acid (GABA)-aminotransferase (AT) inhibitor, shows comparable pharmacokinetics, improved safety and tolerability, and a more favorable toxicity profile when compared with vigabatrin. The pharmacodynamic characteristics of CPP-115 remain to be evaluated. The present study employed state-of-the-art proton magnetic resonance spectroscopy techniques to measure changes in brain GABA+ (the composite resonance of GABA, homocarnosine, and macromolecules) concentrations in healthy subjects receiving oral daily doses of CPP-115 or placebo. Six healthy adult males were randomized to receive either single daily 80 mg doses of CPP-115 (n=4) or placebo (n=2) for 6, 10, or 14 days. Metabolite-edited spectra and two-dimensional J-resolved spectroscopy data were acquired from the parietal-occipital cortex and supplementary motor area in all subjects. Four scans were performed in each subject that included a predrug baseline measure, two scans during the dosing timeframe, and a final scan that occurred 1 week after drug cessation. CPP-115 induced robust and significant increases in brain GABA+ concentrations that ranged between 52 and 141% higher than baseline values. Elevated GABA+ concentrations returned to baseline values following drug clearance. Subjects receiving placebo showed no significant changes in GABA+ concentration. CPP-115-induced changes were exclusive to GABA and homocarnosine, and CPP-115 afforded brain GABA+ concentration changes comparable to or greater than previous vigabatrin spectroscopy studies in healthy epilepsy-naive subjects. The return to baseline GABA+ concentration indicates the reversible GABA-AT resynthesis following drug washout. These preliminary data warrant further spectroscopy studies that characterize the acute pharmacodynamic effects of CPP-115 with additional dose-descending measures.
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Affiliation(s)
- Andrew P Prescot
- Department of Radiology and Imaging Sciences, University of Utah School of Medicine, Salt Lake City, UT, USA,Department of Radiology and Imaging Sciences, University of Utah School of Medicine, 383 Colorow Drive, Salt Lake City, UT 84108, USA, Tel: +1 801 587 1441, Fax: +1 801 585 5375, E-mail:
| | | | | | - Rebekah S Huber
- Department of Psychiatry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Douglas G Kondo
- Department of Psychiatry, University of Utah School of Medicine, Salt Lake City, UT, USA,Rocky Mountain Mental Illness Research, Education, and Clinical Center (MIRECC), Department of Veterans Affairs Medical Center, Salt Lake City, UT, USA
| | - Perry F Renshaw
- Department of Psychiatry, University of Utah School of Medicine, Salt Lake City, UT, USA,Rocky Mountain Mental Illness Research, Education, and Clinical Center (MIRECC), Department of Veterans Affairs Medical Center, Salt Lake City, UT, USA
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Rasmussen AD, Richmond E, Wegener KM, Downes N, Mullins P. Vigabatrin-induced CNS changes in juvenile rats: Induction, progression and recovery of myelin-related changes. Neurotoxicology 2015; 46:137-44. [DOI: 10.1016/j.neuro.2014.12.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2014] [Revised: 12/09/2014] [Accepted: 12/19/2014] [Indexed: 11/16/2022]
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Puts NA, Edden RA. In vivo magnetic resonance spectroscopy of GABA: a methodological review. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2012; 60:29-41. [PMID: 22293397 PMCID: PMC3383792 DOI: 10.1016/j.pnmrs.2011.06.001] [Citation(s) in RCA: 273] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Accepted: 05/30/2011] [Indexed: 05/06/2023]
Affiliation(s)
- Nicolaas A.J. Puts
- Schools of Bioscience and Psychology, Cardiff University, Park Place, Cardiff, UK
| | - Richard A.E. Edden
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
- FM Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
- Corresponding author. Address: Russell H. Morgan Department of Radiology and Radiological Science, 600 N Wolfe St., Park 367C, Baltimore, MD 21287, USA. Tel.: +1 410 614 3418. (R.A.E. Edden)
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8
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Nasrallah FA, Balcar VJ, Rae CD. Activity-dependent γ-aminobutyric acid release controls brain cortical tissue slice metabolism. J Neurosci Res 2011; 89:1935-45. [DOI: 10.1002/jnr.22649] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 02/15/2011] [Accepted: 03/01/2011] [Indexed: 12/16/2022]
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Nikolov RP, Yakimova KS. Effects of GABA-transaminase inhibitor Vigabatrin on thermoregulation in rats. Amino Acids 2010; 40:1441-5. [PMID: 20878340 DOI: 10.1007/s00726-010-0754-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Accepted: 09/15/2010] [Indexed: 11/24/2022]
Abstract
Vigabatrin is a GABA derivative (gamma-vinyl GABA) which inhibits irreversibly the enzyme activity of GABA transaminase and thus increased indirectly brain GABA concentrations. We have used body temperature assay to examine the effects of Vigabatrin on thermoregulation in intact rats. In order to understand the mechanism of thermoregulatory action of Vigabatrin at cellular level, we have investigated its effect on individual warm-sensitive preoptic area/anterior hypothalamus (PO/AH) neurons in rat brain slice preparations. The results of the present study suggest that Vigabatrin produced dose-dependent hypothermia in rats and also increased temperature sensitivity of warm-sensitive PO/AH neurons.
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Affiliation(s)
- Rumen P Nikolov
- Department of Pharmacology and Toxicology, Faculty of Medicine, Medical University, 2 Zdrave Street, Sofia, Bulgaria.
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10
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Mattson RH, Petroff OA, Rothman D, Behar K. Vigabatrin: effect on brain GABA levels measured by nuclear magnetic resonance spectroscopy. ACTA NEUROLOGICA SCANDINAVICA. SUPPLEMENTUM 2009; 162:27-30. [PMID: 7495186 DOI: 10.1111/j.1600-0404.1995.tb00496.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Vigabatrin is undoubtedly one of the most exciting anti-epilepsy drugs in use today. Many open and controlled clinical trials have confirmed that it is particularly effective in controlling partial epileptic seizures with or without secondary generalization. Vigabatrin acts to increase GABA levels in the presynaptic nerve terminal by inhibiting the activity of GABA-transaminase. There is no direct correlation between the blood or brain concentration of vigabatrin and its clinical effect, so monitoring vigabatrin levels is not predictive of patient response. However, it is possible to relate the activity of vigabatrin to levels of GABA in the brain, measured by nuclear magnetic resonance spectroscopy (NMRS). NMRS studies show that following administration of vigabatrin, brain concentrations of GABA rise to about 2-3 times their baseline values. This 'extra' GABA is held within the nerve terminal, and is only released during synaptic transmission. Although there appears to be a clear dose-response relationship up to 3 g/day, it is not well documented if higher doses result in proportionately higher brain GABA levels. This finding seems to support the results of clinical studies suggesting that the optimal dose of vigabatrin may be 3 g/day. There is also some evidence for a correlation between the concentration of GABA in the brain and the clinical outcome. Continuing investigations using NMRS aim to confirm these preliminary findings, and to determine the time course and extent of changes in brain GABA levels after vigabatrin administration.
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Affiliation(s)
- R H Mattson
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510, USA
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12
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Chen Z, Silva AC, Yang J, Shen J. Elevated endogenous GABA level correlates with decreased fMRI signals in the rat brain during acute inhibition of GABA transaminase. J Neurosci Res 2005; 79:383-91. [PMID: 15619231 DOI: 10.1002/jnr.20364] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Vigabatrin and gabaculine, both highly specific inhibitors of GABA (gamma-aminobutyric acid) transaminase, cause significant elevation of endogenous GABA levels in brain. The time course of GABA concentration after acute GABA transaminase inhibition was measured quantitatively in the alpha-chloralose-anesthetized rat brain using in vivo selective homonuclear polarization transfer spectroscopy. The blood oxygenation level-dependent (BOLD) effect in functional magnetic resonance imaging (fMRI) has been considered to be coupled tightly to neuronal activation via the metabolic demand of associated glutamate transport. Correlated with the rise in endogenous GABA level after vigabatrin or gabaculine treatment, the intensity of BOLD-weighted fMRI signals in rat somatosensory cortex during forepaw stimulation was found to be reduced significantly. These results are consistent with previous findings that inhibition of GABA transaminase leads to augmented GABA release and potentiation of GABAergic inhibition.
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Affiliation(s)
- Zhengguang Chen
- Molecular Imaging Branch, NIMH, Bethesda, MD 20892-1527, USA
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Steinhoff BJ, Hirsch E, Mutani R, Nakken KO. The ideal characteristics of antiepileptic therapy: an overview of old and new AEDs. Acta Neurol Scand 2003; 107:87-95. [PMID: 12580856 DOI: 10.1034/j.1600-0404.2003.01311.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
New and improved anti-epileptic drugs (AEDs) have made the concept of choice, according to the individual prognosis and probable response to specific regimens, increasingly feasible. Inter-individual variability in syndrome severity and complexity make individualization necessary. We propose three categories of disorder control according to the individual objectives of the patient: (1) seizure control, (2) epilepsy control and ultimately, (3) "epilepsy cure"; the latter remaining a largely idealistic target today. An AED is likely to be successful if it exhibits "optimal" characteristics, such as drug efficacy, tolerability, pharmacokinetics, interactions and cost-effectiveness. This review discusses the "optimal" characteristics of add-on AEDs, which, in addition to seizure control, will contribute to the achievement of epilepsy control and therefore address the currently unmet clinical needs of epilepsy treatment.
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Affiliation(s)
- B J Steinhoff
- Epilepsy Centre Kork, Landstr. 1, Kehl-Kork, Germany.
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Juhász C, Muzik O, Chugani DC, Shen C, Janisse J, Chugani HT. Prolonged vigabatrin treatment modifies developmental changes of GABA(A)-receptor binding in young children with epilepsy. Epilepsia 2001; 42:1320-6. [PMID: 11737167 DOI: 10.1046/j.1528-1157.2001.05401.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To determine whether prolonged treatment with vigabatrin (VGB), an antiepileptic drug (AED) that acts by elevating brain gamma-aminobutyric acid (GABA) levels, interferes with age-related changes of in vivo GABA(A)-receptor binding in children with epilepsy. METHODS Using [11C]flumazenil (FMZ)-positron emission tomography (PET) imaging, 15 children (aged 1-8 years) with medically intractable epilepsy were studied. Seven of these children were treated with VGB (1,000-2,500 mg/day) for > or =3 months before the FMZ-PET study. The remaining eight patients were medicated with other drugs that are known not to act directly on the GABAergic system. Absolute quantification of PET data was performed by using the volume of distribution (VD) of FMZ in brain tissue representing FMZ ligand binding. RESULTS After controlling for age, hemispheric FMZ VD values were significantly lower in children treated with VGB as compared with the non-VGB group (p = 0.012). Regional FMZ VD values of the VGB-treated patients were significantly lower in all cortical regions and the cerebellum, whereas the difference was not significant in the thalamus and basal ganglia. No significant drug effect or drug-by-region interaction could be determined when the patients were separated according to treatment with carbamazepine (p = 0.97) or valproate (p = 0.55). CONCLUSIONS VGB induces a decrease in GABA(A)-receptor binding in the cortex and cerebellum of the developing epileptic brain. A similar effect of other drugs and substances of abuse targeting the GABAergic system may be hypothesized. Because of the important role of the GABAergic system in developmental plasticity, the reversibility and functional consequences of this age-specific drug effect should be further studied.
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Affiliation(s)
- C Juhász
- Department of Pediatrics, Children's Hospital of Michigan, The Detroit Medical Center, Wayne State University School of Medicine, Detroit, Michigan 48201, USA
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Gidal BE, Privitera MD, Sheth RD, Gilman JT. Vigabatrin: a novel therapy for seizure disorders. Ann Pharmacother 1999; 33:1277-86. [PMID: 10630829 DOI: 10.1345/aph.18376] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE To review the pharmacology, pharmacokinetics, efficacy, and adverse effects of vigabatrin and its role in the management of seizure disorders. METHODS A MEDLINE search of English-language literature from January 1993 through January 1999 was conducted using vigabatrin as a search term to identify pertinent studies and review articles. Additional studies were identified from the bibliographies of reviewed literature. The manufacturer provided postmarketing surveillance data. Priority was given to randomized, double-blind, placebo-controlled studies. FINDINGS Vigabatrin is a selective and irreversible inhibitor of gamma-aminobutyric acid transaminase. In controlled clinical trials of vigabatrin add-on therapy in patients with uncontrolled partial seizures, 24-67% of patients achieved a < or =50% reduction in seizure frequency. Data from two comparative trials with carbamazepine monotherapy indicate that vigabatrin monotherapy reduces the frequency of partial seizures in patients with newly diagnosed epilepsy. Vigabatrin also controls infantile spasms, particularly those associated with tuberous sclerosis. Vigabatrin is more effective in patients with partial seizures than in those with generalized seizures. The drug is generally well tolerated. Headache and drowsiness were the most common adverse effects observed in controlled clinical trials; visual field defects, psychiatric reactions, and hyperactivity also have been reported. There are no known clinically significant drug interactions. CONCLUSIONS Vigabatrin improves seizure control as add-on therapy for refractory partial seizures and may produce therapeutic benefits in the treatment of infantile spasms. Vigabatrin is generally well tolerated, with a convenient administration schedule, a lack of known significant drug interactions, and no need for routine monitoring of plasma concentrations.
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Affiliation(s)
- B E Gidal
- School of Pharmacy and Department of Neurology, University of Wisconsin, Madison 53706, USA.
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Abstract
The development of medications used in the treatment of epilepsy has accelerated over the past decade, and has benefited from a parallel growth in our knowledge of the basic mechanisms underlying neuronal excitability and synchronization. This understanding of the pharmacologic basis of antiepileptic drug (AED) action has, in large part, arisen from recent advances in cellular and molecular biology, coupled with avenues of drug discovery that have departed somewhat from the largely empiric approaches of the past. Physicians now have available to them an ever-growing armentarium of AEDs, necessitating a firmer appreciation of their mechanisms of action if more rational approaches toward both clinical application and research are to be adopted. An important example in this regard is the concept of rational polypharmacy for patients with epilepsy who are refractory to monotherapy. This review summarizes our current understanding of the molecular targets of clinically significant AEDs, comparing and contrasting their differing mechanisms of action.
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Affiliation(s)
- J M Rho
- Department of Neurology, University of Washington School of Medicine, Seattle, USA.
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Abstract
Magnetic resonance imaging (MRI) is a well known diagnostic tool in radiology that produces unsurpassed images of the human body, in particular of soft tissue. However, the medical community is often not aware that MRI is an important yet limited segment of magnetic resonance (MR) or nuclear magnetic resonance (NMR) as this method is called in basic science. The tremendous morphological information of MR images sometimes conceal the fact that MR signals in general contain much more information, especially on processes on the molecular level. NMR is successfully used in physics, chemistry, and biology to explore and characterize chemical reactions, molecular conformations, biochemical pathways, solid state material, and many other applications that elucidate invisible characteristics of matter and tissue. In medical applications, knowledge of the molecular background of MRI and in particular MR spectroscopy (MRS) is an inevitable basis to understand molecular phenomenon leading to macroscopic effects visible in diagnostic images or spectra. This review shall provide the necessary background to comprehend molecular aspects of magnetic resonance applications in medicine. An introduction into the physical basics aims at an understanding of some of the molecular mechanisms without extended mathematical treatment. The MR typical terminology is explained such that reading of original MR publications could be facilitated for non-MR experts. Applications in MRI and MRS are intended to illustrate the consequences of molecular effects on images and spectra.
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Affiliation(s)
- C Boesch
- Department of Clinical Research, University of Bern, Switzerland
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Abstract
PURPOSE Changes in gamma-aminobutyric acid (GABA) physiology are important in determining seizure susceptibility in the developing nervous system. Noninvasive measurements of brain GABA in adults with epilepsy have demonstrated important relations among seizure control, brain GABA levels, and changes in brain GABA with drugs designed to alter GABA metabolism. The purpose of this study was to demonstrate the changes in GABA in the occipital lobes of children with epilepsy after treatment with vigabatrin (VGB). METHODS Ten proton nuclear magnetic resonance spectroscopic (NMRS) studies were obtained on four subjects with epilepsy. The subjects were between ages 1 and 5 years. Occipital lobe GABA levels were measured before and after treatment with VGB. RESULTS Brain GABA levels increased significantly in these subjects after VGB treatment (p < 0.05, paired Student's t test). In one subject, brain GABA was decreased in the region of the epileptic focus compared with the homologous region of the opposite hemisphere. A nearly fivefold increase in GABA occurred in the epileptic region after VGB treatment in this subject. CONCLUSIONS VGB increases brain GABA levels in children with epilepsy. NMRS can be used to monitor the response of brain GABA levels to drugs known to alter GABA physiology and serve as an important tool to understand the role of GABA-mediated inhibition in pediatric epilepsies.
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Affiliation(s)
- E J Novotny
- Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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Abstract
A gradient-based multiple quantum filtering method is presented for in vivo chemical shift imaging of gamma-aminobutyric acid (GABA) in the human brain, which provides effective suppression of the overlapping creatine singlet with close to optimal detection efficiency. It is shown by product operator calculations and coherence pathway analysis that under conditions of no B1 and B0 inhomogeneity gradient filtering retains 75% of the two outer resonance lines of the GABA-4 triplet with no creatine contamination. A variation of the method with 100% retention of the GABA-4 outer resonance lines but higher sensitivity to B1 inhomogeneity is also discussed. By using a localized version of the sequence with an 8-cm surface coil for transmission and detection, it was found in phantom experiments at 2.1 T that a 69% signal retention of the two outer resonance lines of the GABA-4 triplet was achieved relative to a spin echo sequence with inhibition of GABA J modulation. A creatine suppression ratio of 2000:1 was measured. The use of the method for chemical shift imaging of GABA is demonstrated by coronal images obtained from phantoms and from the occipital lobe of a healthy volunteer.
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Affiliation(s)
- J Shen
- Department of Internal Medicine, School of Medicine, Yale University, New Haven, Connecticut, USA
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Baulac M, Cavalcanti D, Semah F, Arzimanoglou A, Portal JJ. Gabapentin add-on therapy with adaptable dosages in 610 patients with partial epilepsy: an open, observational study. The French Gabapentin Collaborative Group. Seizure 1998; 7:55-62. [PMID: 9548227 DOI: 10.1016/s1059-1311(98)90009-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The objectives were to evaluate gabapentin add-on therapy in a large population under conditions close to real practice and to determine the therapeutic doses as reached with adaptable dosages. A 6-month multicentre, open-label study, involved addition of gabapentin to pre-existing treatment at the initial dosage of 1200 mg and subsequent adjustment between 900 and 2400 mg/day according to efficacy and tolerability. A study group of 610 adult patients, with partial epilepsy, persistent seizures and a median seizure frequency with a baseline of 7.2 per month were recruited; one-third had less than four seizures per month. Polypharmacy was frequent, with a mean of 2.3 concomitant drugs. After 6 months, 368 patients (62%) continued on gabapentin, at a mean dosage of 1739 mg/day with 44% of responders. On an intention-to-treat basis, median reduction in frequency was 21.2%, and the responder rate was 33.9%. The responder rate increased to 40.7% in the less severe subgroup receiving only one concomitant drug. Seventy-nine patients (13.4%) remained without seizures during the last evaluation period, versus nine (1.5%) during the baseline. Most of them had initially less than four seizures per month. The most frequent adverse effects, somnolence (29.3%), asthenia (14.6%), nausea (7.9%), ataxia (7.7%) and vertigo (7.2%), occurred rapidly after initial titration to 1200 mg/day, and were usually transitory. Weight gain (8.8%) seemed to be related to gabapentin dose. The combination of two recent drugs, vigabatrin and gabapentin, in 190 patients led to similar efficacy levels, with a tendency for more frequent somnolence and asthenia.
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Affiliation(s)
- M Baulac
- Epilepsy Unit, Hôpital de la Pitié-Salpêtrière, Paris, France
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O'Connor WM, Davidson BL, Kaplitt MG, Abbey MV, During MJ, Leone P, Langer D, O'Connor MJ, Freese A. Adenovirus vector-mediated gene transfer into human epileptogenic brain slices: prospects for gene therapy in epilepsy. Exp Neurol 1997; 148:167-78. [PMID: 9398459 DOI: 10.1006/exnr.1997.6658] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
As a first step in the development of a gene therapy approach to epilepsy, we evaluated the ability of adenovirus vectors to direct the transfer into and expression of a marker gene in human brain slices obtained from patients undergoing surgery for medically intractable epilepsy. Following injection of adenovirus vectors containing the Escherichia coli lacZ gene into hippocampal and cortical brain slices, lacZ mRNA, beta-galactosidase protein, and enzymatic activity were detected, confirming successful gene transfer, transcription, and translation into a functional protein. Transfected cells were predominantly glial, with some neurons expressing beta-galactosidase as well. These results support the potential of adenovirus vectors to transfer genetic information into human epileptogenic brain, resulting in expression of the gene into a functional protein. These findings also have implications for the development of gene therapy approaches to certain seizure disorders. A number of potential therapeutic approaches are discussed, including the elevation of inhibitory neurotransmitter or neuropeptide levels, expression or modulation of postsynaptic receptors, and manipulation of signal transduction systems.
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Affiliation(s)
- W M O'Connor
- Department of Neurosurgery, Thomas Jefferson University Hospital, Philadelphia, PA 19107, USA
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22
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Mavroudakis N, Caroyer JM, Brunko E, Zegers de Beyl D. Effects of vigabatrin on motor potentials evoked with magnetic stimulation. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY 1997; 105:124-7. [PMID: 9152205 DOI: 10.1016/s0924-980x(96)96607-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We studied the effect of an acute loading dose of vigabatrin on threshold of motor responses and duration of silent period elicited with cortical magnetic stimulation in normal subjects. In contrast to phenytoin, vigabatrin does not increase the motor threshold of first dorsal interosseus muscle. We also show that, although vigabatrin increases GABA concentrations in the central nervous system, duration of silent period studied at various stimulus intensities is not modified after vigabatrin administration.
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Affiliation(s)
- N Mavroudakis
- Laboratoire de Neurophysiologie clinique, Hôpital Erasme, Bruxelles, Belgium
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23
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Goldensohn ES, Porter RJ, Schwartzkroin PA. The American Epilepsy Society: an historic perspective on 50 years of advances in research. Epilepsia 1997; 38:124-50. [PMID: 9024195 DOI: 10.1111/j.1528-1157.1997.tb01088.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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24
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Petroff OA, Rothman DL, Behar KL, Mattson RH. Low brain GABA level is associated with poor seizure control. Ann Neurol 1996; 40:908-11. [PMID: 9007096 DOI: 10.1002/ana.410400613] [Citation(s) in RCA: 107] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Low gamma-aminobutyric acid (GABA) concentrations in the cerebrospinal fluid are seen in a variety of epileptic syndromes. Low GABA levels outside of the epileptic focus may facilitate spread of discharges beyond the focus. In vivo measurements of GABA were made by 1H spectroscopy using a 2.1-T magnetic resonance imager-spectrometer and an 8-cm surface coil to measure a 14-cm3 volume in the occipital lobe. Patients with complex partial seizures had lower GABA levels (1.03 mmol/kg of brain; 95% confidence interval [CI], 0.95-1.12; n = 28; p < 0.02) than did subjects without epilepsy (1.18; 95% CI, 1.13-1.24; n = 19). There was a significant association between low GABA levels and recent seizures (correlation coefficient of 0.548, p < 0.01, df of 32). Conversely, patients with well-controlled seizures had higher brain GABA levels than did patients with recent seizures. Patients with seizures within a day of the measurement had lower GABA levels (0.92 mmol/kg; 95% CI, 0.78-1.06; n = 7) than did patients who were seizure free for 5 years or longer (1.28; 95% CI, 1.09-1.47; n = 4). Poor seizure control is associated with low brain GABA levels.
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Affiliation(s)
- O A Petroff
- Department of Neurology, Yale University, New Haven, CT 06510, USA
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25
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Pitkänen A, Tuunanen J, Halonen T. Vigabatrin and carbamazepine have different efficacies in the prevention of status epilepticus induced neuronal damage in the hippocampus and amygdala. Epilepsy Res 1996; 24:29-45. [PMID: 8800633 DOI: 10.1016/0920-1211(95)00093-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The present study compares the efficacy of carbamazepine (20 mg/kg/day) and vigabatrin (250 mg/kg/day) in preventing hippocampal and amygdaloid damage in the perforant pathway stimulation model of status epilepticus in the rat. One group of rats received a combination of the drugs. Drug treatments were started one week before the stimulation and continued for two weeks thereafter. Gallyas silver impregnation and somatostatin immunohistochemistry were used to detect neuronal damage. All drug treatments were equally effective in decreasing the number and severity of seizures during electrical stimulation. In the vigabatrin group, the damage to the hilar somatostatin-immunoreactive (SOM-ir) neurons and hippocampal CA3c pyramidal cells was less severe than in the vehicle (SOM-ir, P < 0.01; CA3c, P < 0.05) and carbamazepine (SOM-ir, P < 0.01; CA3c, P < 0.05) groups. In the carbamazepine and combination groups, the severity of neuronal damage in the hippocampus did not differ from that in vehicle-treated animals. The amygdaloid neurons were not protected by any of the treatments. Our results show that even though vigabatrin and carbamazepine treatments had similar anticonvulsant efficacy during the perforant pathway stimulation, only vigabatrin but not carbamazepine decreased seizure-induced neuronal damage. Vigabatrin decreased neuronal damage in the hippocampus but not in the amygdala. These results demonstrate that different brain regions and neuronal networks may be protected unequally by different anticonvulsants.
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Affiliation(s)
- A Pitkänen
- A.I. Virtanen Institute, University of Kuopio, Finland.
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26
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Petroff OA, Rothman DL, Behar KL, Lamoureux D, Mattson RH. The effect of gabapentin on brain gamma-aminobutyric acid in patients with epilepsy. Ann Neurol 1996; 39:95-9. [PMID: 8572673 DOI: 10.1002/ana.410390114] [Citation(s) in RCA: 220] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Gabapentin has come into clinical use as adjunctive therapy in the treatment of epilepsy. Designed to mimic gamma-aminobutyric acid (GABA), its mechanism of action remains elusive. In vivo measurements of GABA in human brain were made using 1H magnetic resonance spectroscopy. We used a 2.1-T magnetic resonance imager-spectrometer and an 8-cm surface coil to measure a 13.5-cm3 volume in the occipital cortex. GABA levels were measured in 14 patients enrolled in an open-lbel trial of gabapentin. GABA was elevated in patients taking gabapentin compared with 14 complex partial epilepsy patients, matched for antiepileptic drug treatment. Brain GABA levels appeared to be higher in patients taking high-dose gabapentin (3,300-3,600 mg/day) than in those taking standard doses (1,200-2,400 mg/day). Gabapentin appears to increase human brain GABA levels.
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Affiliation(s)
- O A Petroff
- Department of Neurology, Yale University, New Haven, CT 06510, USA
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27
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Cox IJ. Development and applications of in vivo clinical magnetic resonance spectroscopy. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 1996; 65:45-81. [PMID: 9029941 DOI: 10.1016/s0079-6107(96)00006-5] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
4.1 CURRENT STATUS. While an extensive clinical literature of MRS of muscle, brain, heart and liver has been achieved, the MRS technique is not considered essential for routine diagnosis because it is inherently insensitive and metabolic changes tend to be small. However, MRS techniques have proven to be of considerable value for prognosis in some circumstances, notably for predicting outcome following hypoxic-ischaemic injury in the newborn and also in predicting graft viability following organ transplantation. The chemical specificity of MRS has been illustrated, and exploiting the non-invasive nature of the technique, metabolic fingerprinting of pathophysiological processes throughout the natural history of a wide variety of diseases is now being accomplished. Particularly exciting are the applications of 13C MRS for measuring hepatic and muscle glycogen levels, for example in diabetics, and the use of hepatic 31P MRS for assessing liver function in cirrhosis. Other areas of excitement are the applications of 1H MRS in assessing neuronal function in epilepsy and stroke, and for measuring the evolution of lactate in stroke and hypoxic-ischaemic encephalopathy. Emphasis on technique development continues, and applications still tend to be technology-led. The availability of routine clinical MRI systems with spectroscopy capabilities has given MRS studies wider applicability. The recent improvements in spatial resolution have been impressive and the technique is slowly becoming more quantitative. 4.2. FUTURE PERSPECTIVES. Given the flexibility of clinical magnetic resonance techniques, particularly magnetic resonance imaging, it is likely that MRI will be the diagnostic tool of choice in a wider range of diseases, such as multiple sclerosis, stroke, neurodegenerative conditions, sports injuries and in staging malignancies. Since proton magnetic resonance spectroscopy packages have become a routine addition to many MRI systems, it is feasible to select the MRI sequences of most value in highlighting anatomical and pathological abnormalities and to incorporate specifically selected MRS sequences to emphasize biochemical differences. Improvements in technical methodologies are central to further developments. For example, use of internal coils, such as implantable or endoscopic coils, will enable small regions of tissue to be studied in considerable detail, which may otherwise be inaccessible to measurement. Chemical MRS studies have benefited from the use of higher magnetic fields, and the same may be expected for clinical MRS studies. Whole-body magnets up to 4 T have been used in a few centres, and certainly 3 T systems are becoming more widely available with the recent tremendous interest in functional imaging. Certainly, better control of artefacts can be expected; for example, improved definition of spectral changes due to voluntary or involuntary movements. Wider use of proton decoupling methods will improve the specificity of the spectra, by allowing definitive assignments of overlapping resonances, as well as the sensitivity. Comparing PET and MRS studies, it is becoming increasingly obvious that both will be required in parallel to explore parameters of brain metabolism and function. The ability to measure 13C MR signals in the brain has been demonstrated, which allows measurements of glutamate and glucose turnover. MRS measurements have the advantage of not requiring a radioactive isotope, as well as being insensitive to activity-related changes in regional cerebral blood flow. Also the study of cerebral glucose metabolism by MRS is very promising, allowing a resolution and sensitivity comparable to PET. A combination of MRS and PET studies will allow the pathogenesis of neuropsychiatric disorders to be better understood. (ABSTRACT TRUNCATED)
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Affiliation(s)
- I J Cox
- Robert Steiner Magnetic Resonance Unit, Royal Postgraduate Medical School, London, U.K
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29
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Abstract
As clinical experience with the pharmacokinetic properties and optimal dosing of the established antiepileptic drugs (AEDs) has increased, frequent monitoring of AED concentration in the blood may be less necessary than it was 15 to 25 years ago. Monitoring continues to be valuable at initiation of treatment, addition or removal of other interacting drugs, at the time of unexpected seizure breakthrough, or when symptoms suggest AED toxicity. Occasional determination to monitor compliance may also be appropriate. Blood level determinations of certain of the new, less familiar AEDs, including felbamate, lamotrigine, and oxcarbazapine, appear to be useful. However, new approaches are needed to monitor the efficacy and possible toxicity of other new AEDs for which the correlation between blood concentration of AED and clinical outcome is less clear. For administration of these AEDs, including gabapentin, tiagabine, and vigabatrin, other indirect measures, such as determination of gamma-aminobutyric acid (GABA) levels in the cerebrospinal fluid or by nuclear magnetic resonance spectroscopy, may prove useful. For monitoring compliance, alternate technologies, such as a medication-dispensing vial with an electronic memory chip, may be of clinical value. In the clinical management of patients with epilepsy, blood level monitoring plays an important role, but methods of using this monitoring have evolved with increased experience and the introduction of AEDs with new mechanisms of action.
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Affiliation(s)
- R H Mattson
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut 06520-8018, USA
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30
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Rogvi-Hansen B, Gram L. Adverse effects of established and new antiepileptic drugs: an attempted comparison. Pharmacol Ther 1995; 68:425-34. [PMID: 8788565 DOI: 10.1016/0163-7258(95)02014-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Seizures are but one aspect of the negative impact epilepsy has on patients' lives. Adverse effects of antiepileptic treatment may affect the patient's quality of life to an even greater extent than the occurrence of seizures. Adverse effects of antiepileptic drugs (AEDs) are common, and because the differences in efficacy are often marginal, adverse effects may be the most important factor in choosing the best AED for the patient. The search for more efficient and less toxic agents is constantly ongoing. Current evidence suggests that the new generation of AEDs is as efficient as the established AEDs and exhibits fewer adverse effects, but the scientific evidence from randomised clinical trials comparing established and new AEDs with each other is still pending.
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Affiliation(s)
- B Rogvi-Hansen
- University Clinic of Neurology, Hvidovre Hospital, Denmark
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31
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Abstract
We have reviewed the pharmacokinetics of six antiepileptic drugs that are marketed (felbamate, gabapentin, lamotrigine, oxcarbazepine, vigabatrin, and zonisamide) and six drugs that are undergoing evaluation (levetiracetam, ralitoline, remacemide, stiripentol, tiagabine, and topiramate). In addition, we have compared the prodrugs eterobarb and fosphenytoin and the controlled-release formulations of valproic acid and carbamazepine with their parent compounds. Finally, we have devised a scoring system to compare the pharmacokinetics of new antiepileptic drugs. Using this system, vigabatrin, levetiracetam, gabapentin, and topiramate appea to have the most favourable pharmacokinetic profiles, whilst ralitoline and stiripentol have the least favourable.
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Affiliation(s)
- M C Walker
- University Department of Clinical Neurology, Institute of Neurology, London, UK
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32
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Abstract
Nuclear magnetic resonance (NMR) spectroscopy permits noninvasive, serial measurements of several metabolites with important neurobiologic roles in localized brain regions in vivo. Over the last decade, this technique has been applied to investigations of both animals and humans with epilepsy. Several nuclei that include specific proton, phosphorus, and carbon isotopes provide NMR signals that measure specific compounds in vivo. This paper reviews the studies that have used these multinuclear NMR techniques to investigate the role of these methods in the diagnosis and pathogenesis of epilepsy.
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Affiliation(s)
- E J Novotny
- Yale University, School of Medicine, Department of Pediatrics, New Haven, CT 06510, USA
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33
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Petroff OA, Pleban LA, Spencer DD. Symbiosis between in vivo and in vitro NMR spectroscopy: the creatine, N-acetylaspartate, glutamate, and GABA content of the epileptic human brain. Magn Reson Imaging 1995; 13:1197-211. [PMID: 8750337 DOI: 10.1016/0730-725x(95)02033-p] [Citation(s) in RCA: 113] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
High resolution 1H NMR spectroscopy was used to analyze temporal lobe biopsies obtained from patients with epilepsy. Heat-stabilized cerebrum, dialyzed cytosolic macromolecules, and perchloric acid extracts were studied using one- and two-dimensional spectroscopy. Anterior temporal lobe neocortex was enriched in GABA, glutamate, alanine, N-acetylaspartate, and creatine. Subjacent white matter was enriched in aspartate, glutamine, and inositol. The N-acetylaspartate/creatine mole ratio was lower in anterior temporal neocortex with mesial (0.66) than neocortical (0.80) temporal lobe epilepsy. Human brain biopsy samples were separated into crude and refined synaptosomes, neuronal cell bodies, and glia using density gradient centrifugation. Neuronal fractions were enriched in glutamate and N-acetylaspartate. Glial cell fractions were enriched in lactate, glutamine, and inositol. The creatine content was the same in biopsied epileptic cortex (8.8-8.9 mmol/kg) and normal in vivo occipital lobe (8.9 mmol/kg). Glutamate content was higher in epileptic cortex at biopsy (10.1-10.5 mmol/kg) than normal in vivo occipital lobe (8.8 mmol/kg). GABA content was higher in biopsies of epileptic cortex (2.3-2.2 mmol/kg) than in normal in vivo occipital lobe (1.2 mmol/kg). N-acetylaspartate content was lower in biopsied epileptic temporal cortex (5.8-6.8 mmol/kg) than normal in vivo occipital lobe (8.9 mmol/kg). Paired in vivo and ex vivo measurements are critical for a firm understanding of the changes seen in the 1H-spectra from patients with epilepsy.
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Affiliation(s)
- O A Petroff
- Department of Neurology, Yale University, New Haven, CT 06510, USA
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34
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Abstract
Epilepsy is characterized by recurrent seizures. Many epilepsies with focal seizures as well as convulsive generalized seizures respond satisfactorily to antiepileptic drugs (AEDs) that reduce repetitive firing (e.g., phenytoin, carbamazepine, and valproate) or that augment GABAA-mediated inhibition (e.g., phenobarbital and benzodiazepines). A number of drugs presently under development, such as NMDA receptor antagonists, loreclezole, losigamone, methysticine, and dextromethorphan, are promising in acute animal models of otherwise drug-resistant convulsant activity. As a result of recent studies in both experimental models and surgically resected human epileptic brain, the prospects for development of AEDs have significantly improved. Several new AEDs recently have reached the commercial market or are in experimental or clinical trials. A comparative presentation of the standing of the new AEDs with respect to their efficacy and side effects is necessary, but still very difficult. Because initial experience with new AEDs is restricted to populations with severe drug-resistant epilepsy, the crucial question whether potential new AEDs can alter prognosis is not yet definitively answered. There is a clear need to compare the effects of standard AEDs and new AEDs in naive patients and over longer follow-up periods. Moreover, because of the strong desire to develop antiepileptic therapy that directly treats the primary etiology of a given epileptic syndrome, or modifies the neurobiological processes that cause recurrent seizures, better experimental epilepsy models for chronic epilepsy and further clinical studies are necessary to increase the knowledge on the pathophysiology of distinct epileptic syndromes. In this respect, studies on the differences between responders and nonresponders to a given AED treatment are extremely valuable.
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Affiliation(s)
- H G Wieser
- Department of Neurology, University Hospital Zürich, Switzerland
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