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Ismail FS, Faustmann PM, Förster E, Corvace F, Faustmann TJ. Tiagabine and zonisamide differentially regulate the glial properties in an astrocyte-microglia co-culture model of inflammation. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2023; 396:3253-3267. [PMID: 37231170 PMCID: PMC10567966 DOI: 10.1007/s00210-023-02538-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 05/16/2023] [Indexed: 05/27/2023]
Abstract
Due to the role of astrocytes and microglia in the pathophysiology of epilepsy and limited studies of antiseizure medication (ASM) effects on glial cells, we studied tiagabine (TGB) and zonisamide (ZNS) in an astrocyte-microglia co-culture model of inflammation. Different concentrations of ZNS (10, 20, 40, 100 µg/ml) or TGB (1, 10, 20, 50 µg/ml) were added to primary rat astrocytes co-cultures with 5-10% (M5, physiological conditions) or 30-40% (M30, pathological inflammatory conditions) microglia for 24 h, aiming to study glial viability, microglial activation, connexin 43 (Cx43) expression and gap-junctional coupling. ZNS led to the reduction of glial viability by only 100 µg/ml under physiological conditions. By contrast, TGB revealed toxic effects with a significant, concentration-dependent reduction of glial viability under physiological and pathological conditions. After the incubation of M30 co-cultures with 20 µg/ml TGB, the microglial activation was significantly decreased and resting microglia slightly increased, suggesting possible anti-inflammatory features of TGB under inflammatory conditions. Otherwise, ZNS caused no significant changes of microglial phenotypes. The gap-junctional coupling was significantly decreased after the incubation of M5 co-cultures with 20 and 50 µg/ml TGB, which can be related to its anti-epileptic activity under noninflammatory conditions. A significant decrease of Cx43 expression and cell-cell coupling was found after the incubation of M30 co-cultures with 10 µg/ml ZNS, suggesting additional anti-seizure effects of ZNS with the disruption of glial gap-junctional communication under inflammatory conditions. TGB and ZNS differentially regulated the glial properties. Developing novel ASMs targeting glial cells may have future potential as an "add-on" therapy to classical ASMs targeting neurons.
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Affiliation(s)
- Fatme Seval Ismail
- Department of Neurology, University Hospital Knappschaftskrankenhaus Bochum, Ruhr University Bochum, Bochum, Germany.
| | - Pedro M Faustmann
- Department of Neuroanatomy and Molecular Brain Research, Medical Faculty, Ruhr University Bochum, Bochum, Germany
| | - Eckart Förster
- Department of Neuroanatomy and Molecular Brain Research, Medical Faculty, Ruhr University Bochum, Bochum, Germany
| | - Franco Corvace
- Department of Neuroanatomy and Molecular Brain Research, Medical Faculty, Ruhr University Bochum, Bochum, Germany
| | - Timo Jendrik Faustmann
- Department of Psychiatry and Psychotherapy, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany
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2
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Zhu A, Huang J, Kong F, Tan J, Lei J, Yuan Y, Yan C. Molecular basis for substrate recognition and transport of human GABA transporter GAT1. Nat Struct Mol Biol 2023:10.1038/s41594-023-00983-z. [PMID: 37400655 DOI: 10.1038/s41594-023-00983-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Accepted: 03/31/2023] [Indexed: 07/05/2023]
Abstract
γ-Aminobutyric acid (GABA), an important inhibitory neurotransmitter in the central nervous system, is recycled through specific GABA transporters (GATs). GAT1, which is mainly expressed in the presynaptic terminals of axons, is a potential drug target of neurological disorders due to its essential role in GABA transport. Here we report four cryogenic electron microscopy structures of human GAT1, at resolutions of 2.2-3.2 Å. GAT1 in substrate-free form or in complex with the antiepileptic drug tiagabine exhibits an inward-open conformation. In the presence of GABA or nipecotic acid, inward-occluded structures are captured. The GABA-bound structure reveals an interaction network bridged by hydrogen bonds and ion coordination for GABA recognition. The substrate-free structure unwinds the last helical turn of transmembrane helix TM1a to release sodium ions and substrate. Complemented by structure-guided biochemical analyses, our studies reveal detailed mechanism of GABA recognition and transport, and elucidate mode of action of the inhibitors, nipecotic acid and tiagabine.
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Affiliation(s)
- Angqi Zhu
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Junhao Huang
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Fang Kong
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Jiaxin Tan
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Jianlin Lei
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yafei Yuan
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China.
| | - Chuangye Yan
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China.
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3
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Tasdemiroglu Y, Gourdie RG, He JQ. In vivo degradation forms, anti-degradation strategies, and clinical applications of therapeutic peptides in non-infectious chronic diseases. Eur J Pharmacol 2022; 932:175192. [PMID: 35981605 DOI: 10.1016/j.ejphar.2022.175192] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 08/01/2022] [Accepted: 08/05/2022] [Indexed: 11/03/2022]
Abstract
Current medicinal treatments for diseases comprise largely of two categories: small molecular (chemical) (e.g., aspirin) and larger molecular (peptides/proteins, e.g., insulin) drugs. Whilst both types of therapeutics can effectively treat different diseases, ranging from well-understood (in view of pathogenesis and treatment) examples (e.g., flu), to less-understood chronic diseases (e.g., diabetes), classical small molecule drugs often possess significant side-effects (a major cause of drug withdrawal from market) due to their low- or non-specific targeting. By contrast, therapeutic peptides, which comprise short sequences from naturally occurring peptides/proteins, commonly demonstrate high target specificity, well-characterized modes-of-action, and low or non-toxicity in vivo. Unfortunately, due to their small size, linear permutation, and lack of tertiary structure, peptidic drugs are easily subject to rapid degradation or loss in vivo through chemical and physical routines, thus resulting in a short half-life and reduced therapeutic efficacy, a major drawback that can reduce therapeutic efficiency. However, recent studies demonstrate that the short half-life of peptidic drugs can be significantly extended by various means, including use of enantiomeric or non-natural amino acids (AAs) (e.g., L-AAs replacement with D-AAs), chemical conjugation [e.g., with polyethylene glycol], and encapsulation (e.g., in exosomes). In this context, we provide an overview of the major in vivo degradation forms of small therapeutic peptides in the plasma and anti-degradation strategies. We also update on the progress of small peptide therapeutics that are either currently in clinical trials or are being successfully used in clinical therapies for patients with non-infectious diseases, such as diabetes, multiple sclerosis, and cancer.
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Affiliation(s)
- Yagmur Tasdemiroglu
- Department of Biomedical Sciences and Pathobiology, College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Robert G Gourdie
- Center for Vascular and Heart Research, Fralin Biomedical Research Institute, Virginia Tech, Roanoke, VA, 24016, USA
| | - Jia-Qiang He
- Department of Biomedical Sciences and Pathobiology, College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, 24061, USA.
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4
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Kelly AM, Berry MR, Tasker SZ, McKee SA, Fan TM, Hergenrother PJ. Target-Agnostic P-Glycoprotein Assessment Yields Strategies to Evade Efflux, Leading to a BRAF Inhibitor with Intracranial Efficacy. J Am Chem Soc 2022; 144:12367-12380. [PMID: 35759775 DOI: 10.1021/jacs.2c03944] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The blood-brain barrier (BBB) presents a major hurdle in the development of central nervous system (CNS) active therapeutics, and expression of the P-glycoprotein (P-gp) efflux transporter at the blood-brain interface further impedes BBB penetrance of most small molecules. Designing efflux liabilities out of compounds can be laborious, and there is currently no generalizable approach to directly transform periphery-limited agents to ones active in the CNS. Here, we describe a target-agnostic, prospective assessment of P-gp efflux using diverse compounds. Our results demonstrate that reducing the molecular size or appending a carboxylic acid in many cases enables evasion of P-gp efflux in cell-based experiments and in mice. These strategies were then applied to transform a periphery-limited V600EBRAF inhibitor, dabrafenib, into versions that possess potent and selective anti-cancer activity but now also evade P-gp-mediated efflux. When compared to dabrafenib, the compound developed herein (everafenib) has superior BBB penetrance and superior efficacy in an intracranial mouse model of metastatic melanoma, suggesting it as a lead candidate for the treatment of melanoma metastases to the brain and gliomas with BRAF mutation. More generally, the results described herein suggest the actionability of the trends observed in these target-agnostic efflux studies and provide guidance for the conversion of non-BBB-penetrant drugs into versions that are BBB-penetrant and efficacious.
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Affiliation(s)
- Aya M Kelly
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Matthew R Berry
- Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Sarah Z Tasker
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Sydney A McKee
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Timothy M Fan
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Cancer Center at Illinois, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Paul J Hergenrother
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Cancer Center at Illinois, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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5
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Singh K, Kumar P, Bhatia R, Mehta V, Kumar B, Akhtar MJ. Nipecotic acid as potential lead molecule for the development of GABA uptake inhibitors; structural insights and design strategies. Eur J Med Chem 2022; 234:114269. [DOI: 10.1016/j.ejmech.2022.114269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 03/05/2022] [Accepted: 03/05/2022] [Indexed: 11/04/2022]
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6
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Eckl R, Fischer S, Sonnleitner CM, Schmidhuber D, Rehbein J, Reiser O. Stereoselective Synthesis of Biologically Relevant Tetrahydropyridines and Dihydro-2 H-pyrans via Ring-Expansion of Monocyclopropanated Heterocycles. ACS ORGANIC & INORGANIC AU 2021; 2:169-174. [PMID: 36855453 PMCID: PMC9954292 DOI: 10.1021/acsorginorgau.1c00042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A stereoselective, scalable, and metal-free ring-expansion of monocyclopropanated pyrroles and furans has been developed, leading to value-added highly functionalized tetrahydropyridine and dihydro-2H-pyran derivatives. Featuring a cyclopropylcarbinyl cation rearrangement as the key step, the selective cleavage of the unactivated endocyclic cyclopropane C-C bond is achieved. Targeted transformations of the thus obtained six-membered heterocycles give access to versatile building blocks with relevance for drug synthesis.
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7
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Wurzer N, Klimczak U, Babl T, Fischer S, Angnes RA, Kreutzer D, Pattanaik A, Rehbein J, Reiser O. Heck-Type Coupling of Fused Bicyclic Vinylcyclopropanes: Synthesis of 1,2-Dihydropyridines, 2,3-Dihydro-1 H-azepines, 1,4-Cyclohexadienes, and 2 H-Pyrans. ACS Catal 2021. [DOI: 10.1021/acscatal.1c02564] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Nikolai Wurzer
- Institute of Organic Chemistry, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Urszula Klimczak
- Institute of Organic Chemistry, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Tobias Babl
- Institute of Organic Chemistry, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Sebastian Fischer
- Institute of Organic Chemistry, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Ricardo A. Angnes
- Institute of Chemistry, University of Campinas, Rua Carlos Gomes, 241, Cidade Universitária, Campinas, 13083-970 São Paulo, Brazil
| | - Dominik Kreutzer
- Institute of Organic Chemistry, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Aryaman Pattanaik
- Institute of Organic Chemistry, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Julia Rehbein
- Institute of Organic Chemistry, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
| | - Oliver Reiser
- Institute of Organic Chemistry, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
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8
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Zhu C, Mandrelli F, Zhou H, Maji R, List B. Catalytic Asymmetric Synthesis of Unprotected β 2-Amino Acids. J Am Chem Soc 2021; 143:3312-3317. [PMID: 33645969 PMCID: PMC7953379 DOI: 10.1021/jacs.1c00249] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
![]()
We report here a
scalable, catalytic one-pot approach to enantiopure
and unmodified β2-amino acids. A newly developed
confined imidodiphosphorimidate (IDPi) catalyzes a broadly applicable
reaction of diverse bis-silyl ketene acetals with a silylated aminomethyl
ether, followed by hydrolytic workup, to give free β2-amino acids in high yields, purity, and enantioselectivity. Importantly,
both aromatic and aliphatic β2-amino acids can be
obtained using this method. Mechanistic studies are consistent with
the aminomethylation to proceed via silylium-based asymmetric counteranion-directed
catalysis (Si-ACDC) and a transition state to explain the enantioselectivity
is suggested on the basis of density functional theory calculation.
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Affiliation(s)
- Chendan Zhu
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Francesca Mandrelli
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Hui Zhou
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Rajat Maji
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Benjamin List
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
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Chuang SH, Reddy DS. Isobolographic Analysis of Antiseizure Activity of the GABA Type A Receptor-Modulating Synthetic Neurosteroids Brexanolone and Ganaxolone with Tiagabine and Midazolam. J Pharmacol Exp Ther 2019; 372:285-298. [PMID: 31843812 DOI: 10.1124/jpet.119.261735] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 12/13/2019] [Indexed: 12/11/2022] Open
Abstract
Epilepsy is often treated with a combination of antiepileptic drugs. Although neurosteroids are potent anticonvulsants, little is known about their combination potential for the treatment of refractory epilepsy. Here, we investigated the combination efficacy of neurosteroids allopregnanolone (AP, brexanolone) and ganaxolone (GX) with the GABA-reuptake inhibitor tiagabine (TG) or the benzodiazepine midazolam (MDZ) on tonic inhibition in dentate gyrus granule cells and seizure protection in the hippocampus kindling and 6-Hz seizure models. Isobolographic analysis indicated that combinations of GX and TG or AP and TG at three standard ratios (1:1, 3:1, and 1:3) displayed significant synergism in augmenting tonic inhibition. In pharmacological studies, GX, AP, and TG produced dose-dependent antiseizure effects in mice (ED50 = 1.46, 4.20, and 0.20 mg/kg, respectively). The combination of GX and TG at the fixed ratio of 1:1 exerted the greatest combination index (CI = 0.53), indicating strong synergistic interaction in seizure protection. In addition, combination regimens of AP and TG showed robust synergism for seizure protection (CI = 0.4). Finally, combination regimens of GX and MDZ elicited synergistic (CI = 0.6) responses for seizure protection. These results demonstrate striking synergism of neurosteroids and TG combination for seizure protection, likely because of their effects at extrasynaptic GABA type A (GABA-A) receptors from TG-induced elevation in GABA levels. Superadditive antiseizure activity of neurosteroid-MDZ combinations may stem from their actions at both synaptic and extrasynaptic GABA-A receptors. Together, these findings provide a potential mechanistic basis for combination potential of neurosteroids with TG or benzodiazepines for the management of refractory epilepsy, status epilepticus, and seizure disorders. SIGNIFICANCE STATEMENT: This paper investigates for the first time the potential synergistic interactions between two neurosteroids with anticonvulsant properties, allopregnanolone (brexanolone) and the very similar synthetic analog, ganaxolone, and two conventional antiepileptic drugs active at GABA type A receptors: the GABA-reuptake inhibitor tiagabine and a benzodiazepine, midazolam. The results demonstrate a synergistic protective effect of neurosteroid-tiagabine combinations, as well as neurosteroid-midazolam regimens in seizure models.
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Affiliation(s)
- Shu-Hui Chuang
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, Bryan, Texas
| | - Doodipala Samba Reddy
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, Bryan, Texas
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10
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Bresnahan R, Martin‐McGill KJ, Hutton JL, Marson AG. Tiagabine add-on therapy for drug-resistant focal epilepsy. Cochrane Database Syst Rev 2019; 10:CD001908. [PMID: 31608990 PMCID: PMC6953346 DOI: 10.1002/14651858.cd001908.pub4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Epilepsy is a common neurological condition that affects up to 1% of the population. Nearly 30% of people with epilepsy are resistant to currently available antiepileptic drugs (AEDs) and require treatment with multiple antiepileptic drugs in combination. Tiagabine is one of the newer AEDs that can be used as an adjunct (add-on) to standard AEDs. OBJECTIVES To evaluate the efficacy and tolerability of tiagabine when used as an add-on treatment for people with drug-resistant focal seizures. SEARCH METHODS This is an updated Cochrane review, last published in 2014. For the latest update, we searched the following databases on 22 January 2019: Cochrane Register of Studies (CRS Web), which includes the Cochrane Epilepsy Group's Specialized Register and the Cochrane Central Register of Controlled Trials, MEDLINE (Ovid, 1946 to January 21, 2019), ClinicalTrials.gov, and the WHO International Clinical Trials Registry Platform. We imposed no language restrictions. We also contacted the manufacturers of tiagabine and experts in the field to identify any ongoing or unpublished studies. SELECTION CRITERIA We included randomised placebo-controlled add-on trials conducted in people of any age with focal epilepsy. The studies could be double-, single-, or unblinded and of parallel or cross-over design. They had to have a minimum treatment period of eight weeks. We also included trials using an active drug control group. DATA COLLECTION AND ANALYSIS Two review authors independently assessed trials for inclusion and extracted data according to the standard methodological procedures expected by the Cochrane Collaboration for this review update. We resolved disagreements by discussion. Outcomes investigated included 50% or greater reduction in seizure frequency, treatment withdrawal, adverse effects, effects on cognition and quality of life. The primary analyses were performed by intention-to-treat. We calculated worst-case and best-case analyses for seizure outcomes. We evaluated dose response using regression models. Two review authors assessed risk of bias in each study using the Cochrane 'Risk of bias' tool. MAIN RESULTS No further studies were added since the previous update in 2014. The review included six trials (four parallel-group and two cross-over group trials) consisting of 948 participants. For the main comparison, tiagabine versus placebo, all participants were aged between 12 and 77 years and the study treatment periods ranged from 12 to 22 weeks. The overall risk ratio (RR) with 95% confidence intervals (CIs) for a 50% or greater reduction in seizure frequency (tiagabine versus placebo) was 3.16 (95% CI 1.97 to 5.07; 3 trials; 769 participants; high-certainty evidence). Because of differences in response rates among trials, regression models were unable to provide reliable estimates of response to individual doses. The RR for treatment withdrawal (tiagabine versus placebo) was 1.81 (95% CI 1.25 to 2.62; 3 trials, 769 participants; moderate-certainty evidence). Dizziness and tremor were significantly associated with tiagabine therapy. For cognitive and quality-of-life outcomes, the limited available data suggested no significant effects on cognition, mood, or adjustment. One trial comparing tiagabine with an active drug control group (tiagabine versus topiramate) found no significant differences between the two add-on drugs for a 50% or greater reduction in seizure frequency (RR 0.54, 95% CI 0.19 to 1.58; 1 trial; 41 participants) or for treatment withdrawal (RR 1.43, 95% CI 0.74 to 2.74; one trial; 41 participants). We judged two of the six included studies to have low risk of bias, three studies to have an unclear risk of bias, and one study to have a high risk of bias. Methods for randomisation sequence generation were the least reported trial design factor and generated the most concerns regarding risk of bias. We rated the overall certainty of the evidence as largely moderate to high using the GRADE approach. We rated the evidence for two of the adverse effect outcomes, nausea and tremor, as low certainty. AUTHORS' CONCLUSIONS Tiagabine reduced seizure frequency but was associated with some adverse effects when used as an add-on treatment in people with drug-resistant focal epilepsy. The findings of the current review are mainly applicable to adults and adolescents, and may not necessarily be applicable to children as none of the trials included participants aged under 12 years. We found no significant differences between tiagabine and topiramate as add-on drugs; however, evidence was provided by a single trial and was therefore limited.
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Affiliation(s)
- Rebecca Bresnahan
- Institute of Translational Medicine, University of LiverpoolDepartment of Molecular and Clinical PharmacologyLower LaneLiverpoolUKL9 7LJ
| | - Kirsty J Martin‐McGill
- Institute of Translational Medicine, University of LiverpoolDepartment of Molecular and Clinical PharmacologyLower LaneLiverpoolUKL9 7LJ
- University of ChesterDepartment of Clinical Sciences and NutritionFaculty of Medicine, Dentistry and Life SciencesChesterUK
| | - Jane L Hutton
- University of WarwickDepartment of StatisticsCoventryUKCV4 7AL
| | - Anthony G Marson
- Institute of Translational Medicine, University of LiverpoolDepartment of Molecular and Clinical PharmacologyLower LaneLiverpoolUKL9 7LJ
- The Walton Centre NHS Foundation TrustLiverpoolUK
- Liverpool Health PartnersLiverpoolUK
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11
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Títoff V, Moury HN, Títoff IB, Kelly KM. Seizures, Antiepileptic Drugs, and CKD. Am J Kidney Dis 2019; 73:90-101. [DOI: 10.1053/j.ajkd.2018.03.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 03/06/2018] [Indexed: 01/19/2023]
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12
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Turjanski N, Lloyd GG. Psychiatric side-effects of medications: recent developments. ACTA ACUST UNITED AC 2018. [DOI: 10.1192/apt.11.1.58] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Medications often induce neuropsychiatric side-effects. This article reviews psychiatric side-effects that are well known and describes those induced by recently developed medications. Therapeutic innovations have been prominent in the treatment of HIV infection, Parkinson's disease and epilepsy and therefore psychiatric side-effects caused by these agents are described in more detail.
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13
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Abstract
As the field of PET has expanded and an ever-increasing number and variety of compounds have been radiolabeled as potential in vivo tracers of biochemistry, transporters have become important primary targets or facilitators of radiotracer uptake and distribution. A transporter can be the primary target through the development of a specific high-affinity radioligand: examples are the multiple high-affinity radioligands for the neuronal membrane neurotransmitter or vesicular transporters, used to image nerve terminals in the brain. The goal of a radiotracer might be to study the function of a transporter through the use of a radiolabeled substrate, such as the application of 3-O-[11C]methyl]glucose to measure rates of glucose transport through the blood-brain barrier. In many cases, transporters are required for radiotracer distributions, but the targeted biochemistries might be unrelated: an example is the use of 2-deoxy-2-[18F]FDG for imaging glucose metabolism, where initial passage of the radiotracer through cell membranes requires the action of specific glucose transporters. Finally, there are transporters such as p-glycoprotein that function to extrude small molecules from tissues, and can effectively work against successful uptake of radiotracers. The diversity of structures and functions of transporters, their importance in human health and disease, and their role in therapeutic drug disposition suggest that in vivo imaging of transporter location and function will continue to be a point of emphasis in PET radiopharmaceutical development. In this review, the variety of transporters and their importance for in vivo PET radiotracer development and application are discussed. Transporters have thus joined the other major protein targets such as G-protein coupled receptors, ligand-gated ion channels, enzymes, and aggregated proteins as of high interest for understanding human health and disease.
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Affiliation(s)
- Michael R Kilbourn
- Department of Radiology, University of Michigan Medical School, Ann Arbor, MI.
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Taranto-Montemurro L, Sands SA, Edwards BA, Azarbarzin A, Marques M, de Melo C, Eckert DJ, White DP, Wellman A. Effects of Tiagabine on Slow Wave Sleep and Arousal Threshold in Patients With Obstructive Sleep Apnea. Sleep 2017; 40:2667756. [PMID: 28364504 PMCID: PMC6084757 DOI: 10.1093/sleep/zsw047] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2016] [Indexed: 12/30/2022] Open
Abstract
Introduction Obstructive sleep apnea (OSA) severity is markedly reduced during slow-wave sleep (SWS) even in patients with a severe disease. The reason for this improvement is uncertain but likely relates to non-anatomical factors (i.e. reduced arousability, chemosensitivity, and increased dilator muscle activity). The anticonvulsant tiagabine produces a dose-dependent increase in SWS in subjects without OSA. This study aimed to test the hypothesis that tiagabine would reduce OSA severity by raising the overall arousal threshold during sleep. Aims and Methods After a baseline physiology night to assess patients' OSA phenotypic traits, a placebo-controlled, double-blind, crossover trial of tiagabine 12 mg administered before sleep was performed in 14 OSA patients. Under each condition, we assessed the effects on sleep and OSA severity using standard clinical polysomnography. Results Tiagabine increased slow-wave activity (SWA) of the electroencephalogram (1-4 Hz) compared to placebo (1.8 [0.4] vs. 2.0 [0.5] LogμV2, p = .04) but did not reduce OSA severity (apnea-hypopnea index [AHI] 41.5 [20.3] vs. 39.1 [16.5], p > .5). SWS duration (25 [20] vs. 26 [43] mins, p > .5) and arousal threshold (-26.5 [5.0] vs. -27.6 [5.1] cmH2O, p = .26) were also unchanged between nights. Conclusions Tiagabine modified sleep microstructure (increase in SWA) but did not change the duration of SWS, OSA severity, or arousal threshold in this group of OSA patients. Based on these findings, tiagabine should not be considered as a therapeutic option for OSA treatment.
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Affiliation(s)
- Luigi Taranto-Montemurro
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham & Women's Hospital & Harvard Medical School, Boston, MA
| | - Scott A Sands
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham & Women's Hospital & Harvard Medical School, Boston, MA
- Department of Allergy, Immunology and Respiratory Medicine and Central Clinical School, The Alfred and Monash University, Melbourne, VIC Australia
| | - Bradley A Edwards
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham & Women's Hospital & Harvard Medical School, Boston, MA
- Sleep and Circadian Medicine Laboratory, Department of Physiology Monash University, Melbourne, VIC, Australia
- School of Psychological Sciences and Monash Institute of Cognitive and Clinical Neurosciences, Monash University, Melbourne, VIC, Australia
| | - Ali Azarbarzin
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham & Women's Hospital & Harvard Medical School, Boston, MA
| | - Melania Marques
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham & Women's Hospital & Harvard Medical School, Boston, MA
| | - Camila de Melo
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham & Women's Hospital & Harvard Medical School, Boston, MA
| | - Danny J Eckert
- Neuroscience Research Australia (NeuRA) and the University of New South Wales, Randwick, Sydney, Australia
| | - David P White
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham & Women's Hospital & Harvard Medical School, Boston, MA
| | - Andrew Wellman
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham & Women's Hospital & Harvard Medical School, Boston, MA
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Tutka P, Kondrat-Wróbel MW, Zaluska K, Żółkowska D, Florek-Łuszczki M, Łuszczki JJ. Cytisine inhibits the protective activity of various classical and novel antiepileptic drugs against 6 Hz-induced psychomotor seizures in mice. Psychopharmacology (Berl) 2017; 234:281-291. [PMID: 27778062 DOI: 10.1007/s00213-016-4461-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Accepted: 10/10/2016] [Indexed: 11/30/2022]
Abstract
BACKGROUND Cytisine (CYT) is a partial agonist of brain α4β2 nicotinic acetylcholine receptors widely used in Central/Eastern Europe for smoking cessation. OBJECTIVES This study evaluated the effect of CYT on the ability of classical and novel antiepileptic drugs to prevent seizures evoked by the 6-Hz test, a model of psychomotor seizures in mice thought as a model of drug-resistant seizures. RESULTS CYT administered intraperitoneally (i.p.) in a dose of 2 mg kg-1 significantly inhibited the anticonvulsant activity of lacosamide, levetiracetam, and pregabalin, increasing their median effective doses 50 (ED50) values from 6.88 to 10.52 mg kg-1 (P < 0.05) for lacosamide, from 22.08 to 38.26 mg kg-1 (P < 0.05) for levetiracetam, and from 40.48 to 64.61 mg kg-1 (P < 0.01) for pregabalin, respectively. There were no significant changes in total brain concentrations of lacosamide, levetiracetam, and pregabalin following CYT i.p. administration. CYT administered in a dose of 2 mg kg-1 failed to change the protective action of clobazam, clonazepam, phenobarbital, tiagabine, and valproate in the 6-Hz test. Neither CYT (2 mg kg-1) alone nor its combination with the anticonvulsant drugs (at their ED50 values from the 6-Hz test) affected motor coordination; skeletal muscular strength and long-term memory, as determined in the chimney; and grip strength and passive avoidance tests, respectively. CONCLUSION CYT-evoked alterations in the protection provided by some antiepileptic drugs against seizures can be of serious concern for epileptic smokers, who might demonstrate therapeutic failure to lacosamide, levetiracetam, and pregabalin, resulting in possible breakthrough seizure attacks.
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Affiliation(s)
- Piotr Tutka
- Department of Pharmacology, University of Rzeszów, Al. Rejtana 16c, 35-959, Rzeszów, Poland. .,Centre for Innovative Research in Medical and Natural Sciences, University of Rzeszów, Pigonia 1, 35-959, Rzeszów, Poland.
| | - Maria W Kondrat-Wróbel
- Department of Pathophysiology, Medical University of Lublin, Jaczewskiego 8b, 20-090, Lublin, Poland
| | - Katarzyna Zaluska
- Department of Pathophysiology, Medical University of Lublin, Jaczewskiego 8b, 20-090, Lublin, Poland
| | - Dorota Żółkowska
- Department of Neurology, School of Medicine, University of California-Davis, Sacramento, CA, USA
| | - Magdalena Florek-Łuszczki
- Centre of Public Health and Health Promotion, Institute of Rural Health, Jaczewskiego 2, 20-950, Lublin, Poland
| | - Jarogniew J Łuszczki
- Department of Pathophysiology, Medical University of Lublin, Jaczewskiego 8b, 20-090, Lublin, Poland.,Isobolographic Analysis Laboratory, Institute of Rural Health, Jaczewskiego 2, 20-950, Lublin, Poland
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Abstract
Life-threatening and benign drug reactions occur frequently in the skin, affecting 8 % of the general population and 2-3 % of all hospitalized patients, emphasizing the need for physicians to effectively recognize and manage patients with drug-induced eruptions. Neurologic medications represent a vast array of drug classes with cutaneous side effects. Approximately 7 % of the United States (US) adult population is affected by adult-onset neurological disorders, reflecting a large number of patients on neurologic drug therapies. This review elucidates the cutaneous reactions associated with medications approved by the US Food and Drug Administration (FDA) to treat the following neurologic pathologies: Alzheimer disease, amyotrophic lateral sclerosis, epilepsy, Huntington disease, migraine, multiple sclerosis, Parkinson disease, and pseudobulbar affect. A search of the literature was performed using the specific FDA-approved drug or drug classes in combination with the terms 'dermatologic,' 'cutaneous,' 'skin,' or 'rash.' Both PubMed and the Cochrane Database of Systematic Reviews were utilized, with side effects ranging from those cited in randomized controlled trials to case reports. It behooves neurologists, dermatologists, and primary care physicians to be aware of the recorded cutaneous adverse reactions and their severity for proper management and potential need to withdraw the offending medication.
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Affiliation(s)
| | | | - Sylvia Hsu
- Department of Dermatology, Baylor College of Medicine, Houston, TX, USA
| | - Joseph S Kass
- Department of Neurology, Baylor College of Medicine, 7200 Cambridge St., 9th Floor, Houston, TX, 77030, USA.
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17
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Johannessen Landmark C, Patsalos PN. Drug interactions involving the new second- and third-generation antiepileptic drugs. Expert Rev Neurother 2014; 10:119-40. [DOI: 10.1586/ern.09.136] [Citation(s) in RCA: 247] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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18
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Abstract
The use of antiepileptic drugs in patients with renal or hepatic disease is common in clinical practice. Since the liver and kidney are the main organs involved in the elimination of most drugs, their dysfunction can have important effects on the disposition of antiepileptic drugs. Renal or hepatic disease can prolong the elimination of the parent drug or an active metabolite leading to accumulation and clinical toxicity. It can also affect the protein binding, distribution, and metabolism of a drug. The protein binding of anionic acidic drugs, such as phenytoin and valproate, can be reduced significantly by renal failure, causing difficulties in the interpretation of total serum concentrations commonly used in clinical practice. Dialysis can further modify the pharmacokinetic parameters or result in significant removal of the antiepileptic drugs. Antiepileptic drugs that are eliminated unchanged by the kidneys or undergo minimal metabolism include gabapentin, pregabalin, vigabatrin, and topiramate when used as monotherapy. Drugs eliminated predominantly by biotransformation include phenytoin, valproate, carbamazepine, tiagabine, and rufinamide. Drugs eliminated by a combination of renal excretion and biotransformation include levetiracetam, lacosamide, zonisamide, primidone, phenobarbital, ezogabine/retigabine, oxcarbazepine, eslicarbazepine, ethosuximide, and felbamate. Drugs in the latter group can be used cautiously in patients with either renal or liver failure. Antiepileptic drugs that are at high risk of being extracted by hemodialysis include ethosuximide, gabapentin, lacosamide, levetiracetam, pregabalin and topiramate. The use of antiepileptic drugs in the presence of hepatic or renal disease is complex and requires great familiarity with the pharmacokinetics of these agents. Closer follow-up of the patients and more frequent monitoring of serum concentrations are required to optimize clinical outcomes.
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Affiliation(s)
- Jorge J Asconapé
- Department of Neurology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA.
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19
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Greenfield LJ. Molecular mechanisms of antiseizure drug activity at GABAA receptors. Seizure 2013; 22:589-600. [PMID: 23683707 PMCID: PMC3766376 DOI: 10.1016/j.seizure.2013.04.015] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 04/16/2013] [Accepted: 04/17/2013] [Indexed: 02/09/2023] Open
Abstract
The GABAA receptor (GABAAR) is a major target of antiseizure drugs (ASDs). A variety of agents that act at GABAARs s are used to terminate or prevent seizures. Many act at distinct receptor sites determined by the subunit composition of the holoreceptor. For the benzodiazepines, barbiturates, and loreclezole, actions at the GABAAR are the primary or only known mechanism of antiseizure action. For topiramate, felbamate, retigabine, losigamone and stiripentol, GABAAR modulation is one of several possible antiseizure mechanisms. Allopregnanolone, a progesterone metabolite that enhances GABAAR function, led to the development of ganaxolone. Other agents modulate GABAergic "tone" by regulating the synthesis, transport or breakdown of GABA. GABAAR efficacy is also affected by the transmembrane chloride gradient, which changes during development and in chronic epilepsy. This may provide an additional target for "GABAergic" ASDs. GABAAR subunit changes occur both acutely during status epilepticus and in chronic epilepsy, which alter both intrinsic GABAAR function and the response to GABAAR-acting ASDs. Manipulation of subunit expression patterns or novel ASDs targeting the altered receptors may provide a novel approach for seizure prevention.
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Affiliation(s)
- L John Greenfield
- Dept. of Neurology, University of Arkansas for Medical Sciences, 4301W. Markham St., Slot 500, Little Rock, AR 72205, United States.
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20
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Miziak B, Chrościńska-Krawczyk M, Błaszczyk B, Radzik I, Czuczwar SJ. Novel approaches to anticonvulsant drug discovery. Expert Opin Drug Discov 2013; 8:1415-27. [DOI: 10.1517/17460441.2013.837047] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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21
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Kataoka K, Hara K, Haranishi Y, Terada T, Sata T. The antinociceptive effect of SNAP5114, a gamma-aminobutyric acid transporter-3 inhibitor, in rat experimental pain models. Anesth Analg 2013; 116:1162-1169. [PMID: 23456665 DOI: 10.1213/ane.0b013e318282dda7] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Gamma-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the mammalian central nervous system. GABAergic transmission has an important role in regulating nociception at the spinal dorsal horn. It is terminated by rapid uptake of the neurotransmitter from the synaptic cleft into neurons and glial cells, via specific GABA transporters (GATs). Among the 4 GATs, GAT-3 has the greatest expression in central nervous system regions closely associated with nociceptive transmission, including the spinal cord. In this study, we examined the antinociceptive effect of intrathecal administration of a selective GAT-3 inhibitor, SNAP5114, on acute, inflammatory, and neuropathic pain in experimental models. METHODS Male Sprague-Dawley rats were used to assess thermal, mechanical, and chemical nociception in the tail flick and hotplate tests, the paw pressure test, and the formalin test. A rotarod test was performed to assess motor function. Chronic constriction injury to the sciatic nerve was induced in the rats. The electronic von Frey test and the plantar test were then performed to assess mechanical allodynia and thermal hyperalgesia. SNAP5114 (10, 50, 100, or 200 μg) was administered intrathecally to examine antinociceptive activity. To confirm whether the action of SNAP5114 was mediated by GABAergic transmission, the GABAA receptor antagonist bicuculline (0.3 μg) or the GABAB receptor antagonist CGP35348 (30 μg) was administered intrathecally before 200 μg of SNAP5114 in the tail flick test, the formalin test, and the electronic von Frey test. RESULTS Spinally applied SNAP5114 in normal rats dose-dependently prolonged withdrawal latencies in the tail flick test and suppressed the late-phase response in the formalin test. SNAP5114 did not affect motor performance. In the chronic constriction injury rats, SNAP5114 inhibited mechanical allodynia dose-dependently. The antinociceptive action of SNAP5114 was partially reversed by bicuculline or CGP35348 at doses at which the antagonist alone did not affect baseline behavioral responses. CONCLUSIONS These results suggest that SNAP5114 exerts antinociceptive effects by activating GABAA and GABAB receptors in the spinal cord. The GAT-3 inhibitor may prove useful in treatment of various painful conditions.
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Affiliation(s)
- Kazunori Kataoka
- From the Department of Anesthesiology, University of Occupational and Environmental Health, School of Medicine, Kitakyushu, Japan
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22
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Johannessen Landmark C, Johannessen SI, Tomson T. Host factors affecting antiepileptic drug delivery-pharmacokinetic variability. Adv Drug Deliv Rev 2012; 64:896-910. [PMID: 22063021 DOI: 10.1016/j.addr.2011.10.003] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Revised: 10/11/2011] [Accepted: 10/14/2011] [Indexed: 01/16/2023]
Abstract
Antiepileptic drugs (AEDs) are the mainstay in the treatment of epilepsy, one of the most common serious chronic neurological disorders. AEDs display extensive pharmacological variability between and within patients, and a major determinant of differences in response to treatment is pharmacokinetic variability. Host factors affecting AED delivery may be defined as the pharmacokinetic characteristics that determine the AED delivery to the site of action, the epileptic focus. Individual differences may occur in absorption, distribution, metabolism and excretion. These differences can be determined by genetic factors including gender and ethnicity, but the pharmacokinetics of AEDs can also be affected by age, specific physiological states in life, such as pregnancy, or pathological conditions including hepatic and renal insufficiency. Pharmacokinetic interactions with other drugs are another important source of variability in response to AEDs. Pharmacokinetic characteristics of the presently available AEDs are discussed in this review as well as their clinical implications.
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23
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Pabel J, Faust M, Prehn C, Wörlein B, Allmendinger L, Höfner G, Wanner KT. Development of an (S)-1-{2-[Tris(4-methoxyphenyl)methoxy]ethyl}piperidine-3-carboxylic acid [(S)-SNAP-5114] Carba Analogue Inhibitor for Murine γ-Aminobutyric Acid Transporter Type 4. ChemMedChem 2012; 7:1245-55. [DOI: 10.1002/cmdc.201200126] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 04/05/2012] [Indexed: 11/06/2022]
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Frankle WG, Cho RY, Mason NS, Chen CM, Himes M, Walker C, Lewis DA, Mathis CA, Narendran R. [11C]flumazenil binding is increased in a dose-dependent manner with tiagabine-induced elevations in GABA levels. PLoS One 2012; 7:e32443. [PMID: 22384252 PMCID: PMC3288104 DOI: 10.1371/journal.pone.0032443] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Accepted: 01/26/2012] [Indexed: 01/14/2023] Open
Abstract
Evidence indicates that synchronization of cortical activity at gamma-band frequencies, mediated through GABA-A receptors, is important for perceptual/cognitive processes. To study GABA signaling in vivo, we recently used a novel positron emission tomography (PET) paradigm measuring the change in binding of the benzodiazepine (BDZ) site radiotracer [11C]flumazenil associated with increases in extracellular GABA induced via GABA membrane transporter (GAT1) blockade with tiagabine. GAT1 blockade resulted in significant increases in [11C]flumazenil binding potential (BPND) over baseline in the major functional domains of the cortex, consistent with preclinical studies showing that increased GABA levels enhance the affinity of GABA-A receptors for BDZ ligands. In the current study we sought to replicate our previous results and to further validate this approach by demonstrating that the magnitude of increase in [11C]flumazenil binding observed with PET is directly correlated with tiagabine dose. [11C]flumazenil distribution volume (VT) was measured in 18 healthy volunteers before and after GAT1 blockade with tiagabine. Two dose groups were studied (n = 9 per group; Group I: tiagabine 0.15 mg/kg; Group II: tiagabine 0.25 mg/kg). GAT1 blockade resulted in increases in mean (± SD) [11C]flumazenil VT in Group II in association cortices (6.8±0.8 mL g−1 vs. 7.3±0.4 mL g−1;p = 0.03), sensory cortices (6.7±0.8 mL g−1 vs. 7.3±0.5 mL g−1;p = 0.02) and limbic regions (5.2±0.6 mL g−1 vs. 5.7±0.3 mL g−1;p = 0.03). No change was observed at the low dose (Group I). Increased orbital frontal cortex binding of [11C]flumazenil in Group II correlated with the ability to entrain cortical networks (r = 0.67, p = 0.05) measured via EEG during a cognitive control task. These data provide a replication of our previous study demonstrating the ability to measure in vivo, with PET, acute shifts in extracellular GABA.
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Affiliation(s)
- W Gordon Frankle
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
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25
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Therapeutic Drug Monitoring of Classical and Newer Anticonvulsants. Ther Drug Monit 2012. [DOI: 10.1016/b978-0-12-385467-4.00012-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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26
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Johannessen SI, Landmark CJ. Antiepileptic drug interactions - principles and clinical implications. Curr Neuropharmacol 2011; 8:254-67. [PMID: 21358975 PMCID: PMC3001218 DOI: 10.2174/157015910792246254] [Citation(s) in RCA: 220] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Revised: 05/10/2010] [Accepted: 05/26/2010] [Indexed: 02/06/2023] Open
Abstract
Antiepileptic drugs (AEDs) are widely used as long-term adjunctive therapy or as monotherapy in epilepsy and other indications and consist of a group of drugs that are highly susceptible to drug interactions. The purpose of the present review is to focus upon clinically relevant interactions where AEDs are involved and especially on pharmacokinetic interactions. The older AEDs are susceptible to cause induction (carbamazepine, phenobarbital, phenytoin, primidone) or inhibition (valproic acid), resulting in a decrease or increase, respectively, in the serum concentration of other AEDs, as well as other drug classes (anticoagulants, oral contraceptives, antidepressants, antipsychotics, antimicrobal drugs, antineoplastic drugs, and immunosupressants). Conversely, the serum concentrations of AEDs may be increased by enzyme inhibitors among antidepressants and antipsychotics, antimicrobal drugs (as macrolides or isoniazid) and decreased by other mechanisms as induction, reduced absorption or excretion (as oral contraceptives, cimetidine, probenicid and antacides). Pharmacokinetic interactions involving newer AEDs include the enzyme inhibitors felbamate, rufinamide, and stiripentol and the inducers oxcarbazepine and topiramate. Lamotrigine is affected by these drugs, older AEDs and other drug classes as oral contraceptives. Individual AED interactions may be divided into three levels depending on the clinical consequences of alterations in serum concentrations. This approach may point to interactions of specific importance, although it should be implemented with caution, as it is not meant to oversimplify fact matters. Level 1 involves serious clinical consequences, and the combination should be avoided. Level 2 usually implies cautiousness and possible dosage adjustments, as the combination may not be possible to avoid. Level 3 refers to interactions where dosage adjustments are usually not necessary. Updated knowledge regarding drug interactions is important to predict the potential for harmful or lacking effects involving AEDs.
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Affiliation(s)
- Svein I Johannessen
- The National Center for Epilepsy, Sandvika, and Department of Pharmacology, Oslo University Hospital, Oslo, Norway
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27
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Brady KT, Gray KM, Tolliver BK. Cognitive enhancers in the treatment of substance use disorders: clinical evidence. Pharmacol Biochem Behav 2011; 99:285-94. [PMID: 21557964 DOI: 10.1016/j.pbb.2011.04.017] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Revised: 03/23/2011] [Accepted: 04/21/2011] [Indexed: 12/31/2022]
Abstract
Attenuation of drug reward has been the major focus of medication development in the addiction area to date. With the growth of research in the area of cognitive neuroscience, the importance of executive function and inhibitory cognitive control in addictive disorders is becoming increasingly apparent. An emerging strategy in the pharmacotherapy of addictions and other psychiatric disorders involves the use of medications that improve cognitive function. In particular, agents that facilitate inhibitory and attentional control, improve abstraction, planning and mental flexibility could be beneficial in the treatment of substance use disorders. Because there are multiple neurotransmitter systems involved in the regulation of cognitive function, agents from a number of drug classes have been tested. In particular, agents acting through the cholinergic, adrenergic and glutamatergic systems have shown potential for improving cognitive function in a number of psychiatric and neurologic disorders, but most of these agents have not been tested in the treatment of individuals with substance use disorders. This manuscript provides a review of clinical data supporting the use of the major classes of cognitive enhancing agents in substance use disorders. Agents that have shown promise in cognitive enhancement in other disorders, and have a theoretical or mechanistic rationale for application to substance use disorders are also highlighted.
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Affiliation(s)
- Kathleen T Brady
- Medical University of South Carolina, Department of Psychiatry, 67 President Street, Charleston, SC 29425, USA.
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28
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Bentué-Ferrer D, Tribut O, Verdier MC. Suivi thérapeutique pharmacologique de la tiagabine. Therapie 2010; 65:51-5. [DOI: 10.2515/therapie/2009065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Accepted: 12/01/2009] [Indexed: 11/20/2022]
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29
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Edens E, Massa A, Petrakis I. Novel pharmacological approaches to drug abuse treatment. Curr Top Behav Neurosci 2010; 3:343-86. [PMID: 21161760 DOI: 10.1007/7854_2009_29] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The field of pharmacologic addiction treatment is expanding rapidly. While there are currently several FDA-approved medications for nicotine, alcohol, and opiate dependence, research into novel pharmacological approaches for these and additional substances is legion. Each drug of abuse, while sharing a common final neural pathway of increasing dopaminergic tone, has unique and individual characteristics that are important in developing improved and varied treatments. In this chapter, we discuss such research and present the neurobiological underpinnings of these explorations. In general, addiction treatment is focused on four areas: (1) reducing withdrawal discomfort, (2) diminishing cravings, (3) blocking rewarding effects of the drug, and (4) treating comorbidities, such as depression or ADHD. We present current ideas in pharmacologic research for nicotine, alcohol, cannabis, stimulants, and opiates.
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Affiliation(s)
- Ellen Edens
- West Haven Veterans Administration Medical Center, West Haven, CT 06516, USA
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30
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Xi ZX, Gardner EL. Hypothesis-driven medication discovery for the treatment of psychostimulant addiction. ACTA ACUST UNITED AC 2009; 1:303-27. [PMID: 19430578 DOI: 10.2174/1874473710801030303] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Psychostimulant abuse is a serious social and health problem, for which no effective treatments currently exist. A number of review articles have described predominantly 'clinic'-based pharmacotherapies for the treatment of psychostimulant addiction, but none have yet been shown to be definitively effective for use in humans. In the present article, we review various 'hypothesis'- or 'mechanism'-based pharmacological agents that have been studied at the preclinical level and evaluate their potential use in the treatment of psychostimulant addiction in humans. These compounds target brain neurotransmitter or neuromodulator systems, including dopamine (DA), gamma-aminobutyric acid (GABA), endocannabinoid, glutamate, opioid and serotonin, which have been shown to be critically involved in drug reward and addiction. For drugs in each category, we first briefly review the role of each neurotransmitter system in psychostimulant actions, and then discuss the mechanistic rationale for each drug's potential anti-addiction efficacy, major findings with each drug in animal models of psychostimulant addiction, abuse liability and potential problems, and future research directions. We conclude that hypothesis-based medication development strategies could significantly promote medication discovery for the effective treatment of psychostimulant addiction.
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Affiliation(s)
- Zheng-Xiong Xi
- National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA.
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Abstract
Subjective tinnitus, the phantom ringing or buzzing sensation that occurs in the absence of sound, affects 12-14% of adults; in some cases the tinnitus is so severe or disabling that patients seek medical treatment. However, although the economic and emotional impact of tinnitus is large, there are currently no FDA-approved drugs to treat this condition. Clinical trials are now underway to evaluate the efficacy of N-methyl-d-aspartate (NMDA) and dopamine D(2) antagonists, selective serotonin reuptake inhibitors (SSRIs), γ-aminobutyric acid (GABA) agonists and zinc dietary supplements. Previous off-label clinical studies, while not definitive, suggest that patients with severe depression may experience improvement in their tinnitus after treatment with antidepressants such as nortriptyline or sertraline. A small subpopulation of patients with what has been described as "typewriter tinnitus" have been shown to gain significant relief from the anticonvulsant carbamazepine. Preliminary studies with misoprostol, a synthetic prostaglandin E1 analogue, and sulpiride, a dopamine D(2) antagonist, have shown promise. Animal behavioral studies suggest that GABA transaminase inhibitors and potassium channel modulators can suppress tinnitus. Additionally, improvements in tinnitus have also been noted in patients taking melatonin for significant sleep disturbances. Like other complex neurological disorders, one drug is unlikely to resolve tinnitus in all patients; therapies targeting specific subgroups are likely to yield the greatest success.
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Affiliation(s)
- R. Salvi
- Center for Hearing and Deafness and Department of Communicative Disorders and Sciences, University at Buffalo, Buffalo, NY 14214, USA
| | - E. Lobarinas
- Center for Hearing and Deafness and Department of Communicative Disorders and Sciences, University at Buffalo, Buffalo, NY 14214, USA
| | - W. Sun
- Center for Hearing and Deafness and Department of Communicative Disorders and Sciences, University at Buffalo, Buffalo, NY 14214, USA
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Lieving LM, Cherek DR, Lane SD, Tcheremissine OV, Nouvion SO. Effects of acute tiagabine administration on aggressive responses of adult male parolees. J Psychopharmacol 2008; 22:144-52. [PMID: 17715212 DOI: 10.1177/0269881107078489] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Experimental and clinical studies have supported a relationship between gamma-aminobutyric acid (GABA) and aggressive behavior in non-humans and humans. Tiagabine is a GABA uptake inhibitor that has been shown to produce acute behavioral effects in animals. In addition, tiagabine has been shown to decrease aggression in agitated patients when administered chronically. The present study was designed to investigate the effects of acute administration of tiagabine on aggressive responding on a laboratory task in adult humans. Ten adult males participated in experimental sessions on the Point Subtraction Aggression Paradigm (PSAP), which provided subjects with aggressive, escape, and monetary-reinforced response options. All subjects received four acute oral doses of Tiagabine (4, 8, 12 and 16 mg) separated by placebo sessions. Tiagabine decreased aggression at doses that either did not affect, or affected to a lesser extent, monetary-reinforced responding. The results are consistent with some prior research using the PSAP showing a possible unique role for GABA in the regulation of human aggression. A possible behavioral mechanism for the rate-decreasing effects on aggressive responding produced in the present study is that tiagabine may modify aggressive responding by suppressing reactions to aversive stimuli.
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Affiliation(s)
- Lori M Lieving
- University of Texas-Houston, Health Science Center, USA.
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33
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Winhusen T, Somoza E, Ciraulo DA, Harrer JM, Goldsmith RJ, Grabowski J, Coleman FS, Mindrum G, Kahn R, Osman S, Mezinskis J, Li SH, Lewis D, Horn P, Montgomery MA, Elkashef A. A double-blind, placebo-controlled trial of tiagabine for the treatment of cocaine dependence. Drug Alcohol Depend 2007; 91:141-8. [PMID: 17629631 DOI: 10.1016/j.drugalcdep.2007.05.028] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2007] [Revised: 05/16/2007] [Accepted: 05/17/2007] [Indexed: 10/23/2022]
Abstract
BACKGROUND The potential efficacy of tiagabine for treating cocaine dependence is suggested by both pre-clinical research and two small clinical trials. METHOD One hundred and forty one participants who met DSM-IV criteria for cocaine dependence were enrolled into this 12-week, double blind, placebo controlled outpatient trial. Participants received either tiagabine (20 mg/day) or matching placebo. All participants received 1h of manualized individual cognitive behavioral therapy on a weekly basis. Outcome measures included cocaine use as determined by self-report confirmed with urine benzoylecgonine (BE) results, and qualitative and quantitative urine toxicology measures. Safety measures included adverse events, EKGs, vital signs, and laboratory tests. RESULTS Seventy-nine participants (i.e., 56%) completed the 12-week trial. The safety results suggest that tiagabine was safe and generally well tolerated by the participants. Participants in both groups improved significantly on cocaine craving and global functioning, with no significant differences between the groups. There were no significant changes in cocaine use as measured by self-report confirmed by urine BE or by quantitative urine toxicology results. Qualitative urine toxicology results suggest a possible weak effect for tiagabine in reducing cocaine use. CONCLUSION These results suggest that tiagabine, at a dose of 20 mg/day, did not have a robust effect in decreasing cocaine use.
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Affiliation(s)
- Theresa Winhusen
- Department of Psychiatry, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267, USA.
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González G, Desai R, Sofuoglu M, Poling J, Oliveto A, Gonsai K, Kosten TR. Clinical efficacy of gabapentin versus tiagabine for reducing cocaine use among cocaine dependent methadone-treated patients. Drug Alcohol Depend 2007; 87:1-9. [PMID: 16930857 DOI: 10.1016/j.drugalcdep.2006.07.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2005] [Revised: 06/27/2006] [Accepted: 07/01/2006] [Indexed: 11/23/2022]
Abstract
BACKGROUND GABAergic medications appear to reduce the reinforcing effects of cocaine by attenuating cocaine-induced dopamine release. This study evaluated gabapentin and tiagabine compared to placebo in reducing cocaine taking behavior. METHODS A total of 76 treatment seeking, cocaine dependent, methadone-treated, predominately Caucasian male subjects were randomly assigned to tiagabine 24 mg/day (N=25), gabapentin 2400 mg/day (N=26) or placebo (N=25) in a 10-week double-blind placebo-controlled trial. Study medications were slowly increased to their full dosages by the end of week 5 and maintained through week 10. The primary outcome measure was thrice-weekly drug free urine samples. RESULTS Treatment retention was significantly less for the gabapentin group relative to the other groups (log rank=5.29, d.f.=1, p=0.02). The proportion of cocaine-free urine samples during weeks 6-10 was significantly larger in the tiagabine treated group (p<0.05). The longitudinal data showed significant change in thrice-weekly cocaine free urines that reached a greater abstinent rate for the tiagabine treated group (22%) compared to gabapentin (5%) or placebo (13%) treated groups. Mixed-effects ordinal regression models showed a significant tiagabine by time interaction compared to gabapentin (Z=2.48, d.f.=1, p=0.01) and placebo (Z=3.90, d.f.=1, p=0.0001). The gabapentin group did not differ from placebo. CONCLUSION Gabapentin showed poor treatment retention and ineffectiveness in reducing cocaine use. Tiagabine significantly reduced cocaine taking behavior compared to placebo or gabapentin among methadone-stabilized cocaine abusers.
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Affiliation(s)
- Gerardo González
- Department of Psychiatry, Yale University, New Haven, CT 06511, USA.
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Dannhardt G, Kiefer W. [Antiepileptics--action principles and structural parameters]. PHARMAZIE IN UNSERER ZEIT 2007; 36:270-81. [PMID: 17623317 DOI: 10.1002/pauz.200600225] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Affiliation(s)
- Gerd Dannhardt
- Institut für Pharmazie der Johannes Gutenberg-Universität Mainz, Staudinger Weg 5, 55099 Mainz.
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36
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Abstract
The number of medications used to treat different types of seizures has increased over the last 10-15 years. Most of the newer antiepileptic drugs (AEDs) are likely to be unfamiliar to many nephrologists. For both the older and newer AEDs, basic pharmacokinetic information, recommendations for drug dosing in patients with reduced kidney function or who are on dialysis, and adverse renal and fluid-electrolyte effects are reviewed. Newer AEDs are less likely to have significant drug-drug interactions than older agents, but are more likely to need dosage adjustment in patients with reduced kidney function. The most common renal toxicities of these drugs include metabolic acidosis, hyponatremia, and nephrolithiasis; interstitial nephritis and other adverse effects are less common. Little is known about the clearance of most of the newer AEDs with high-efficiency hemodialyzers or with peritoneal dialysis. Monitoring of drug levels when available, careful clinical assessment of patients taking AEDs, and close collaboration with neurologists is essential to the management of patients taking AEDs.
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Affiliation(s)
- Rubeen K Israni
- Renal-Electrolyte and Hypertension Division, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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Pushpal D, Shamshul HN. Tiagabine withdrawal-emergent mania. Aust N Z J Psychiatry 2006; 40:719. [PMID: 16866771 DOI: 10.1080/j.1440-1614.2006.01875.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Abstract
A new generation of antiepileptic drugs (AEDs) has reached the market in recent years with ten new compounds: felbamate, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, pregabalin, tiagabine, topiramate, vigabatrin and zonisamide. The newer AEDs in general have more predictable pharmacokinetics than older AEDs such as phenytoin, carbamazepine and valproic acid (valproate sodium), which have a pronounced inter-individual variability in their pharmacokinetics and a narrow therapeutic range. For these older drugs it has been common practice to adjust the dosage to achieve a serum drug concentration within a predefined 'therapeutic range', representing an interval where most patients are expected to show an optimal response. However, such ranges must be interpreted with caution, since many patients are optimally treated when they have serum concentrations below or above the suggested range. It is often said that there is less need for therapeutic drug monitoring (TDM) with the newer AEDs, although this is partially based on the lack of documented correlation between serum concentration and drug effects. Nevertheless, TDM may be useful despite the shortcomings of existing therapeutic ranges, by utilisation of the concept of 'individual reference concentrations' based on intra-individual comparisons of drug serum concentrations. With this concept, TDM may be indicated regardless of the existence or lack of a well-defined therapeutic range. The ten newer AEDs all have different pharmacological properties, and therefore, the usefulness of TDM for these drugs has to be assessed individually. For vigabatrin, a clear relationship between drug concentration and clinical effect cannot be expected because of its unique mode of action. Therefore, TDM of vigabatrin is mainly to check compliance. The mode of action of the other new AEDs would not preclude the applicability of TDM. For the prodrug oxcarbazepine, TDM is also useful, since the active metabolite licarbazepine is measured. For drugs that are eliminated renally completely unchanged (gabapentin, pregabalin and vigabatrin) or mainly unchanged (levetiracetam and topiramate), the pharmacokinetic variability is less pronounced and more predictable. However, the dose-dependent absorption of gabapentin increases its pharmacokinetic variability. Drug interactions can affect topiramate concentrations markedly, and individual factors such as age, pregnancy and renal function will contribute to the pharmacokinetic variability of all renally eliminated AEDs. For those of the newer AEDs that are metabolised (felbamate, lamotrigine, oxcarbazepine, tiagabine and zonisamide), pharmacokinetic variability is just as relevant as for many of the older AEDs. Therefore, TDM is likely to be useful in many clinical settings for the newer AEDs. The purpose of the present review is to discuss individually the potential value of TDM of these newer AEDs, with emphasis on pharmacokinetic variability.
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Keros S, Hablitz JJ. Subtype-Specific GABA Transporter Antagonists Synergistically Modulate Phasic and Tonic GABAA Conductances in Rat Neocortex. J Neurophysiol 2005; 94:2073-85. [PMID: 15987761 DOI: 10.1152/jn.00520.2005] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
GABAergic inhibition in the brain can be classified as either phasic or tonic. γ-Aminobutyric acid (GABA) uptake by GABA transporters (GATs) can limit the time course of phasic currents arising from endogenous and exogenous GABA, as well as decrease a tonically active GABA current. GABA transporter subtypes 1 and 3 (GAT-1 and GAT-3) are the most heavily expressed of the four known GAT subtypes. The role of GATs in shaping GABA currents in the neocortex has not been explored. We obtained patch-clamp recordings from layer II/III pyramidal cells and layer I interneurons in rat sensorimotor cortex. We found that selective GAT-1 inhibition with NO711 decreased the amplitude and increased the decay time of evoked inhibitory postsynaptic currents (IPSCs) but had no effect on the tonic current or spontaneous IPSCs (sIPSCs). GAT-2/3 inhibition with SNAP-5114 had no effect on IPSCs or the tonic current. Coapplication of NO711 and SNAP-5114 substantially increased tonic currents and synergistically decreased IPSC amplitudes and increased IPSC decay times. sIPSCs were not resolvable with coapplication of NO711 and SNAP-5114. The effects of the nonselective GAT antagonist nipecotic acid were similar to those of NO711 and SNAP-5114 together. We conclude that synaptic GABA levels in neocortical neurons are controlled primarily by GAT-1, but that GAT-1 and GAT-2/3 work together extrasynaptically to limit tonic currents. Inhibition of any one GAT subtype does not increase the tonic current, presumably as a result of increased activity of the remaining transporters. Thus neocortical GAT-1 and GAT-2/3 have distinct but overlapping roles in modulating GABA conductances.
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Affiliation(s)
- Sotirios Keros
- Department of Neurobiology and Civitan International Research Center, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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Schwartz TL, Azhar N, Husain J, Nihalani N, Simionescu M, Coovert D, Jindal S, Tirmazi S. An open-label study of tiagabine as augmentation therapy for anxiety. Ann Clin Psychiatry 2005; 17:167-72. [PMID: 16433059 DOI: 10.1080/10401230591002138] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
BACKGROUND At least 50% of patients with anxiety disorders experience only partial response to pharmacotherapy and require augmentation therapy. Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the CNS, and agents that modulate GABA neurotransmission have shown promise in the treatment of anxiety disorders and are often used as augmentation agents. OBJECTIVE This study evaluated tiagabine, a selective GABA reuptake inhibitor (SGRI), as augmentation therapy. METHODS This 8-week, open-label study enrolled patients who remained symptomatic despite adequate drug trials for treatment of anxiety symptoms. Tiagabine augmentation therapy was initiated at 4 mg/d (taken in 2 doses; one in the morning with breakfast and one in the evening with a snack) for 2 days and increased to 8 mg/d for 10 days. Dose was then adjusted according to efficacy/tolerability in increments of 2 mg every 3 days up to a maximum of 20 mg/d. Effect was assessed using the Hamilton Rating Scale for Anxiety (HAM-A), Beck Anxiety Inventory (BAI), Clinical Global Impression (CGI) scale, Pittsburgh Sleep Quality Index (PSQI), and 36-item Short-Form Health Survey (SF-36). RESULTS Of the 18 patients enrolled, 17 were included in the efficacy analysis; one withdrew due to an adverse event prior to post-baseline assessment. Mean final dose of tiagabine was 13 mg/d. Tiagabine as augmentation therapy further reduced anxiety symptoms, as shown by significant decreases in mean HAM-A total and BAI scores at Week 8 (P<0.001). Thirteen patients (76%) responded (> or =50% reduction in HAM-A total score), and 10 patients (59%) achieved remission (HAM-A total score < or =7) at Week 8. Tiagabine improved sleep quality, with a significant reduction seen in PSQI global score at Week 8 (P=.001). Augmentation therapy with tiagabine was generally well tolerated. CONCLUSION These preliminary findings suggest that the SGRI tiagabine may be an effective and generally well tolerated augmentation therapy in patients with anxiety who remain symptomatic despite adequate drug trials for treatment of anxiety symptoms.
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Affiliation(s)
- Thomas L Schwartz
- SUNY Upstate Medical University, Department of Psychiatry, 750 East Adams Street, Syracuse, NY 13210, USA.
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Chiu CS, Brickley S, Jensen K, Southwell A, Mckinney S, Cull-Candy S, Mody I, Lester HA. GABA transporter deficiency causes tremor, ataxia, nervousness, and increased GABA-induced tonic conductance in cerebellum. J Neurosci 2005; 25:3234-45. [PMID: 15788781 PMCID: PMC6725086 DOI: 10.1523/jneurosci.3364-04.2005] [Citation(s) in RCA: 182] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2004] [Revised: 01/25/2005] [Accepted: 01/25/2005] [Indexed: 11/21/2022] Open
Abstract
GABA transporter subtype 1 (GAT1) knock-out (KO) mice display normal reproduction and life span but have reduced body weight (female, -10%; male, -20%) and higher body temperature fluctuations in the 0.2-1.5/h frequency range. Mouse GAT1 (mGAT1) KO mice exhibit motor disorders, including gait abnormality, constant 25-32 Hz tremor, which is aggravated by flunitrazepam, reduced rotarod performance, and reduced locomotor activity in the home cage. Open-field tests show delayed exploratory activity, reduced rearing, and reduced visits to the central area, with no change in the total distance traveled. The mGAT1 KO mice display no difference in acoustic startle response but exhibit a deficiency in prepulse inhibition. These open-field and prepulse inhibition results suggest that the mGAT1 KO mice display mild anxiety or nervousness. The compromised GABA uptake in mGAT1 KO mice results in an increased GABA(A) receptor-mediated tonic conductance in both cerebellar granule and Purkinje cells. The reduced rate of GABA clearance from the synaptic cleft is probably responsible for the slower decay of spontaneous IPSCs in cerebellar granule cells. There is little or no compensatory change in other proteins or structures related to GABA transmission in the mGAT1 KO mice, including GAT1-independent GABA uptake, number of GABAergic interneurons, and GABA(A)-, vesicular GABA transporter-, GAD65-, and GAT3-immunoreactive structures in cerebellum or hippocampus. Therefore, the excessive extracellular GABA present in mGAT1 KO mice results in behaviors that partially phenocopy the clinical side effects of tiagabine, suggesting that these side effects are inherent to a therapeutic strategy that targets the widely expressed GAT1 transporter system.
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Affiliation(s)
- Chi-Sung Chiu
- Division of Biology, California Institute of Technology, Pasadena, California 91125, USA
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42
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Winhusen TM, Somoza EC, Harrer JM, Mezinskis JP, Montgomery MA, Goldsmith RJ, Coleman FS, Bloch DA, Leiderman DB, Singal BM, Berger P, Elkashef A. A placebo-controlled screening trial of tiagabine, sertraline and donepezil as cocaine dependence treatments. Addiction 2005; 100 Suppl 1:68-77. [PMID: 15730351 DOI: 10.1111/j.1360-0443.2005.00992.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIMS To conduct a preliminary evaluation of the safety and efficacy of tiagabine, sertraline or donepezil versus an unmatched placebo control as a treatment for cocaine dependence. DESIGN A 10-week out-patient study was conducted using the Cocaine Rapid Efficacy and Safety Trial (CREST) study design. SETTING This study was conducted at the Cincinnati Medication Development Research Unit (MDRU) and at an affiliated site in Dayton, Ohio. PARTICIPANTS Participants met Diagnostic and Statistical Manual version IV (DSM-IV) criteria for cocaine dependence. Sixty-seven participants were enrolled with 55 completing final study measures. INTERVENTION The targeted daily doses of medication were tiagabine 20 mg, sertraline 100 mg and donepezil 10 mg. All participants received 1 hour of manualized individual cognitive behavioral therapy on a weekly basis. MEASUREMENTS Primary outcome measures of efficacy included urine benzoylecgonine (BE) level, Cocaine Clinical Global Impression Scale-Observer and self-report of cocaine use. Safety measures included adverse events, ECGs, vital signs and laboratory tests. FINDINGS Subjective measures of cocaine dependence indicated significant improvement for all study groups. Generalized estimating equations analysis indicated that the tiagabine group showed a trend toward a significant decrease in urine BE level from baseline to weeks 5-8 (P = 0.10) and non-significant changes for the other study groups. No pattern of physical or laboratory abnormalities attributable to treatment with any of the medications was identified. There were three serious adverse events reported, none of which were related to study procedures. CONCLUSIONS The present findings suggest that tiagabine may be worthy of further study as a cocaine dependence treatment.
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Armer RE, Miller DJ. Advances in potential therapeutic uses of inhibitors of CNS selective amino acid transporters. Expert Opin Ther Pat 2005. [DOI: 10.1517/13543776.11.4.563] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Abstract
Plasticity of ligand-gated ion channels plays a critical role in nervous system development, circuit formation and refinement, and pathological processes. Recent advances have mainly focused on the plasticity of channels gated by excitatory amino acids, including their acclaimed role in learning and memory. These receptors, together with voltage-gated ion channels, have also been known to be subjected to a homeostatic form of plasticity that prevents destabilization of the neurone's function and that of the network during various physiological processes. To date, the plasticity of GABA(A) receptors has been examined mainly from a developmental and a pathological point of view. Little is known about homeostatic mechanisms governing their plasticity. This review summarizes some of the findings on the homeostatic plasticity of tonic and phasic inhibitory activity.
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Affiliation(s)
- Istvan Mody
- Department of Neurology, The David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
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Wu SP, Shyu MK, Liou HH, Gau CS, Lin CJ. Interaction between Anticonvulsants and Human Placental Carnitine Transporter. Epilepsia 2004; 45:204-10. [PMID: 15009220 DOI: 10.1111/j.0013-9580.2004.29603.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE To examine the inhibitory effect of anticonvulsants (AEDs) on carnitine transport by the human placental carnitine transporter. METHODS Uptake of radiolabeled carnitine by human placental brush-border membrane vesicles was measured in the absence and presence of tiagabine (TGB), vigabatrin (VGB), gabapentin (GBP), lamotrigine (LTG), topiramate (TPM), valproic acid (VPA), and phenytoin (PHT). The mechanism of the inhibitory action of TGB was determined. RESULTS Most of the AEDs inhibited placental carnitine transport. Kinetic analyses showed that TGB had the greatest inhibitory effect [50% inhibitory concentration (IC50, 190 microM)], and the order of inhibitory potency was TGB > PHT > GBP > VPA > VGB, TPM > LTG. Further studies showed that TGB competitively inhibited carnitine uptake by the human placental carnitine transporter, suggesting that it may be a substrate for this carrier. CONCLUSIONS Although the involvement of carnitine deficiency in fetal anticonvulsant syndrome requires further evaluation, potential interference with placental carnitine transport by several AEDs was demonstrated. Despite the higher inhibitory potency of TGB, given the therapeutic unbound concentrations, the results for VPA and PHT are probably more clinically significant.
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Affiliation(s)
- Shu-Pei Wu
- School of Pharmacy and Graduate Institute of Clinical Pharmacy, College of Medicine, National Taiwan University Hospital, and College of Medicine, National Taiwan University, Taipei, Taiwan
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Mares P, Slamberová R. Biphasic action of vigabatrin on cortical epileptic after-discharges in rats. Naunyn Schmiedebergs Arch Pharmacol 2004; 369:305-11. [PMID: 14767635 DOI: 10.1007/s00210-004-0865-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2003] [Accepted: 12/20/2003] [Indexed: 10/26/2022]
Abstract
The time course of the anticonvulsant effect of vigabatrin against cortically induced epileptic after-discharges (ADs) was studied in freely moving rats with implanted electrodes. Adult rats (n=30) were exposed to five stimulation sessions each consisting of six stimulation series at 20-min intervals. The first session was a control one, then two groups of animals (n=10 each) were given vigabatrin (600 or 1,200 mg/kg i.p.), the control animals received physiological saline. Stimulation sessions were repeated 1, 24, 48, and 96 hours after the injection. Control animals exhibited an increased transition from the spike-and-wave type of AD to the second, "limbic" type and an increased intensity of movements accompanying stimulation. ADs in the second and subsequent sessions were, however, shorter than in the first session. Vigabatrin facilitated the transition to the second type of AD 1 h after administration but suppressed this transition as well as decreased the number of stimulations eliciting ADs 48 h later. AD duration and the severity of clonic seizures accompanying spike-and-wave ADs were influenced similarly. The effects of the lower dose of vigabatrin were more marked than those of the higher dose. The biphasic action of vigabatrin in our model might be due either to uneven changes of GABA concentration in different brain structures or to an additional mechanism of action. Our results in a cortical model of seizure demonstrate that the sequence of pro- and anticonvulsant actions of vigabatrin is not restricted to seizures of limbic origin and might represent a general phenomenon.
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Affiliation(s)
- Pavel Mares
- Institute of Physiology, Academy of Sciences of the Czech Republic, Vídenská 1083, 142 20 Prague 4, Czech Republic.
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Neels HM, Sierens AC, Naelaerts K, Scharpé SL, Hatfield GM, Lambert WE. Therapeutic drug monitoring of old and newer anti-epileptic drugs. ACTA ACUST UNITED AC 2004; 42:1228-55. [PMID: 15576287 DOI: 10.1515/cclm.2004.245] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractThe aim of the present paper is to provide information concerning the setting up and interpretation of therapeutic drug monitoring (TDM) for anti-epileptic drugs. The potential value of TDM for these drugs (including carbamazepine, clobazam, clonazepam, ethosuximide, felbamate, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, pheneturide, phenobarbital, phenytoin, primidone, tiagabine, topiramate, valproic acid, vigabatrin and zonisamide) is discussed in relation to their mode of action, drug interactions and their pharmacokinetic properties. The review is based upon available literature data and on observations from our clinical practice. Up until approximately 15 years ago anti-epileptic therapeutics were restricted to a very few drugs that were developed in the first half of the 20th century. Unfortunately, many patients were refractory to these drugs and a new generation of drugs has been developed, mostly as add-on therapy. Although the efficacy of the newer drugs is no better, there is an apparent improvement in drug tolerance, combined with a diminished potential for adverse drug interactions. All new anticonvulsant drugs have undergone extensive clinical studies, but information on the relationship between plasma concentrations and effects is scarce for many of these drugs. Wide ranges in concentrations have been published for seizure control and toxicity. Few studies have been undertaken to establish the concentration-effect relationship. This review shows that TDM may be helpful for a number of these newer drugs.
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Affiliation(s)
- Hugo M Neels
- Laboratory of Biochemistry and Toxicology, Ziekenhuis Netwerk Antwerpen Stuivenberg, Antwerp, Belgium.
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Cordato DJ, Mather LE, Herkes GK. Stereochemistry in clinical medicine: a neurological perspective. J Clin Neurosci 2003; 10:649-54. [PMID: 14592610 DOI: 10.1016/j.jocn.2002.10.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Stereoisomers are compounds that have identical sets of atoms configured in the same positions but are arranged differently spatially. Approximately 25% of contemporary drugs are marketed and used as racemates (i.e., as equimolar mixtures of stereoisomers). This may have major clinical implications, as stereoisomers may possess qualitative and/or quantitative differences in pharmacological effects, plasma protein and tissue binding, metabolic and renal clearance. There are many examples of racemic drugs manufactured and used as single stereoisomers in the field of neurology including the anti-Parkinsonian drugs levodopa, selegiline, apomorphine and entacapone, the antiepileptic drugs tiagabine and levetiracetam, the secondary stroke prevention agent clopidogrel and the acetylcholinesterase inhibitor rivastigmine. The role of drug stereochemistry in the re-evaluation of established drugs and the production of new agents is becoming increasingly important as pharmaceutical companies endeavour to show proof of "no penalty" for the introduction of a racemic new drug over one or other of its single stereoisomers.
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Affiliation(s)
- D J Cordato
- Department of Neurology, Bankstown-Lidcombe Hospital, Eldridge Road, Bankstown, NSW, Australia.
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de Borchgrave V, Lienard F, Willemart T, van Rijckevorsel K. Clinical and EEG findings in six patients with altered mental status receiving tiagabine therapy. Epilepsy Behav 2003; 4:326-37. [PMID: 12791336 DOI: 10.1016/s1525-5050(03)00107-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Tiagabine (TGB), a novel GABA reuptake inhibitor antiepileptic drug, has been reported to induce nonconvulsive status epilepticus (NCSE) in patients with generalized or partial onset seizures. We describe six patients with refractory partial epilepsy treated with add-on TGB. They developed acute intermittent or progressive chronic confusion associated with diffuse slowing of the electroencephalogram (EEG), shortly after an increase in dose of TGB. This remitted in each situation after reduction of the daily dose. The possibility of nonconvulsive status epilepticus or toxic encephalopathy is discussed.
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Affiliation(s)
- V de Borchgrave
- Centre neurologique William Lennox, Université Catholique de Louvain, Allée de Clerlande, 6, B-1340 Ottignies-LLN, Belgium
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Johannessen SI, Battino D, Berry DJ, Bialer M, Krämer G, Tomson T, Patsalos PN. Therapeutic drug monitoring of the newer antiepileptic drugs. Ther Drug Monit 2003; 25:347-63. [PMID: 12766564 DOI: 10.1097/00007691-200306000-00016] [Citation(s) in RCA: 224] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The aim of the present review is to discuss the potential value of therapeutic drug monitoring (TDM) of the newer antiepileptic drugs (AEDs) felbamate, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, tiagabine, topiramate, vigabatrin, and zonisamide. Studies of the relationship between serum concentrations and clinical efficacy of these drugs are reviewed, and the potential value of TDM of the drugs is discussed based on their pharmacokinetic properties and mode of action. Analytical methods for the determination of the serum concentrations of these drugs are also briefly described. There are only some prospective data on the serum concentration-effect relationships, and few studies have been designed primarily to study these relationships. As TDM is not widely practiced for the newer AEDs, there are no generally accepted target ranges for any of these drugs, and for most a wide range in serum concentration is associated with clinical efficacy. Furthermore, a considerable overlap in drug concentrations related to toxicity and nonresponse is reported. Nevertheless, the current tentative target ranges for felbamate, gabapentin, lamotrigine, levetiracetam, oxcarbazepine (10-hydroxy-carbazepine metabolite), tiagabine, topiramate, vigabatrin, and zonisamide are 125 to 250 micromol/L, 70 to 120 micromol/L, 10 to 60 micromol/L, 35 to 120 micromol/L, 50 to 140 micomol/L, 50 to 250 nmol/L, 15 to 60 micromol/L, 6 to 278 micromol/L, and 45 to 180 micromol/L, respectively. Further systematic studies designed specifically to evaluate concentration-effect relationships of the new AEDs are urgently needed. Although routine monitoring in general cannot be recommended at present, measurements of some of the drugs is undoubtedly of help with individualization of treatment in selected cases in a particular clinical setting.
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Affiliation(s)
- Svein I Johannessen
- The National Center for Epilepsy, Sandvika, Norway, "Carlo Besta", Milan, Italy.
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