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García-Ayuso D, Pierdomenico JD, Martínez-Vacas A, Vidal-Sanz M, Picaud S, Villegas-Pérez MP. Taurine: a promising nutraceutic in the prevention of retinal degeneration. Neural Regen Res 2024; 19:606-610. [PMID: 37721291 PMCID: PMC10581579 DOI: 10.4103/1673-5374.380820] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 04/13/2023] [Accepted: 05/27/2023] [Indexed: 09/19/2023] Open
Abstract
Taurine is considered a non-essential amino acid because it is synthesized by most mammals. However, dietary intake of taurine may be necessary to achieve the physiological levels required for the development, maintenance, and function of certain tissues. Taurine may be especially important for the retina. The concentration of taurine in the retina is higher than that in any other tissue in the body and taurine deficiency causes retinal oxidative stress, apoptosis, and degeneration of photoreceptors and retinal ganglion cells. Low plasma taurine levels may also underlie retinal degeneration in humans and therefore, taurine administration could exert retinal neuroprotective effects. Taurine has antioxidant, anti-apoptotic, immunomodulatory, and calcium homeostasis-regulatory properties. This review summarizes the role of taurine in retinal health and disease, where it appears that taurine may be a promising nutraceutical.
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Affiliation(s)
- Diego García-Ayuso
- Grupo de Investigación Oftalmología Experimental, Departamento de Oftalmología, Optometría, Otorrinolaringología y Anatomía Patológica, Facultad de Medicina, Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria (IMIB), Campus de Ciencias de la Salud, Murcia, España
| | - Johnny Di Pierdomenico
- Grupo de Investigación Oftalmología Experimental, Departamento de Oftalmología, Optometría, Otorrinolaringología y Anatomía Patológica, Facultad de Medicina, Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria (IMIB), Campus de Ciencias de la Salud, Murcia, España
| | - Ana Martínez-Vacas
- Grupo de Investigación Oftalmología Experimental, Departamento de Oftalmología, Optometría, Otorrinolaringología y Anatomía Patológica, Facultad de Medicina, Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria (IMIB), Campus de Ciencias de la Salud, Murcia, España
| | - Manuel Vidal-Sanz
- Grupo de Investigación Oftalmología Experimental, Departamento de Oftalmología, Optometría, Otorrinolaringología y Anatomía Patológica, Facultad de Medicina, Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria (IMIB), Campus de Ciencias de la Salud, Murcia, España
| | - Serge Picaud
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - María P. Villegas-Pérez
- Grupo de Investigación Oftalmología Experimental, Departamento de Oftalmología, Optometría, Otorrinolaringología y Anatomía Patológica, Facultad de Medicina, Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria (IMIB), Campus de Ciencias de la Salud, Murcia, España
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Rasmussen AD, Truchot N, Dyssegaard A, Fant P. Retinal and Systemic Toxicity of Vigabatrin Is Driven by the S-Enantiomer in the Long Evans Rat. Toxicol Pathol 2023; 51:126-134. [PMID: 37401471 DOI: 10.1177/01926233231179147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/05/2023]
Abstract
In this study, we assessed the toxicity and toxicokinetics of racemic vigabatrin and its S- and R-enantiomers (vigabatrin consists of 50:50% of the two enantiomers) by administering doses of the three test articles to male Long Evans rats via oral gavage. The animals were housed under high-intensity light conditions and the study consisted of an escalating dose phase and a 21-day fixed-dose phase. Systemic toxicity of vigabatrin appears to be due to the Vig-S-enantiomer only, as increasing doses of Vig-S or Vig-RS caused body weight loss, decreased food consumption, and affected activity. Administration of the Vig-R-enantiomer did not cause any such effects. Systemic exposure to R- and S-enantiomers was approximately linear with dose. Compared to administration of the racemate, there appeared to be a tendency for animals to take up higher amounts of Vig-R and lower amounts of Vig-S when administered as enantiomer. Bilateral retinal atrophy was observed in the fixed-dose phase in rats receiving Vig-S (either alone or as part of Vig-RS) and was characterized by irregular thinning and disorganization of the outer nuclear layer and thinning of the photoreceptor layer. The administration of the R-enantiomer alone did not cause any microscopic retinal change.
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Affiliation(s)
| | - Nathalie Truchot
- Charles River Laboratories France Safety Assessment, Saint-Germain-Nuelles, France
| | | | - Pierluigi Fant
- Charles River Laboratories France Safety Assessment, Saint-Germain-Nuelles, France
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Nabbout R, Kuchenbuch M, Chiron C, Curatolo P. Pharmacotherapy for Seizures in Tuberous Sclerosis Complex. CNS Drugs 2021; 35:965-983. [PMID: 34417984 DOI: 10.1007/s40263-021-00835-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/05/2021] [Indexed: 01/18/2023]
Abstract
Epilepsy is one of the main symptoms affecting the lives of individuals with tuberous sclerosis complex (TSC), causing a high rate of morbidity. Individuals with TSC can present with various types of seizures, epilepsies, and epilepsy syndromes that can coexist or appear in relation to age. Focal epilepsy is the most frequent epilepsy type with two developmental and epileptic encephalopathies: infantile spasms syndrome and Lennox-Gastaut syndrome. Active screening and early management of epilepsy is recommended in individuals with TSC to limit its consequences and its impact on quality of life, cognitive outcome and the economic burden of the disease. The progress in the knowledge of the mechanisms underlying epilepsy in TSC has paved the way for new concepts in the management of epilepsy related to TSC. In addition, we are moving from traditional "reactive" and therapeutic choices with current antiseizure medications used after the onset of seizures, to a proactive approach, aimed at predicting and preventing epileptogenesis and the onset of epilepsy with vigabatrin, and to personalized treatments with mechanistic therapies, namely mechanistic/mammalian target of rapamycin inhibitors. Indeed, epilepsy linked to TSC is one of the only epilepsies for which a predictive and preventive approach can delay seizure onset and improve seizure response. However, the efficacy of such interventions on long-term cognitive and psychiatric outcomes is still under investigation.
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Affiliation(s)
- Rima Nabbout
- Reference Centre for Rare Epilepsies, Department of Pediatric Neurology, Necker Enfants Malades University Hospital, APHP, Université de Paris, 149 rue de Sèvres, 75015, Paris, France.
- UMR 1163, Institut National de la Santé et de la Recherche Médicale (INSERM), Imagine Institute, Université de Paris, Paris, France.
| | - Mathieu Kuchenbuch
- Reference Centre for Rare Epilepsies, Department of Pediatric Neurology, Necker Enfants Malades University Hospital, APHP, Université de Paris, 149 rue de Sèvres, 75015, Paris, France
- UMR 1163, Institut National de la Santé et de la Recherche Médicale (INSERM), Imagine Institute, Université de Paris, Paris, France
| | - Catherine Chiron
- Reference Centre for Rare Epilepsies, Department of Pediatric Neurology, Necker Enfants Malades University Hospital, APHP, Université de Paris, 149 rue de Sèvres, 75015, Paris, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR 1141, Neurospin, Gif sur Yvette, France
| | - Paolo Curatolo
- Department of System Medicine, Child Neurology and Psychiatry Unit, Tor Vergata University Hospital, Rome, Italy
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Walters DC, Jansen EEW, Salomons GS, Arning E, Ashcraft P, Bottiglieri T, Roullet JB, Gibson KM. Preferential accumulation of the active S-(+) isomer in murine retina highlights novel mechanisms of vigabatrin-associated retinal toxicity. Epilepsy Res 2020; 170:106536. [PMID: 33385945 DOI: 10.1016/j.eplepsyres.2020.106536] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 11/27/2020] [Accepted: 12/15/2020] [Indexed: 11/17/2022]
Abstract
((S)-(+)/(R)-(-)) vigabatrin (SabrilR; γ-vinyl GABA), an antiepileptic irreversibly inactivating GABA-transaminase, was administered to male C57Bl6 J mice via continuous infusion (0, 40, 80 mg/kg/d) for 12 days. Our study design pooled retina, eye (minus retina), whole brain and plasma from n = 24 animals for each dose to provide n = 8 triplicates per treatment group. Hypothesizing that (S)-(+) VGB (active isomer) would preferentially accumulate in retina, we determined VGB isomers, comprehensive amino acids, and pharmacokinetic parameters. In brain, eye and plasma, the ((S)-(+)/(R)-(-)) ratio varied from 0.73 to 1.29 and 13.3 in retina, accompanied by a partition coefficient (tissue/plasma, ((S)-(+);(R)-(-))) of 5.8;0.34, 0.63;0.49, and 0.51;0.34 in retina, eye and brain, respectively. Racemic VGB (nmol/g; plasma, nmol/mL, range of means for dose) content was: retina, 25-36; eye (minus retina), 4.8-8.0; brain, 3.1-6.8 and plasma, 8.7-14.9. GABA tissue content (nmol/g) was 1246-3335, 18-64 and 2615-3200 as a function of VGB dose for retina, eye (minus retina) and brain, respectively. The retinal glial cell toxin 2-aminoadipic acid also increased with VGB dose (76-96 nmol/g). Partitioning of active (S)-(+) VGB to retina suggests the involvement of a stereospecific transporter, the identification of which could reveal new therapeutic paradigms that might mitigate VGB's well-known retinal toxicity and expand its clinical utility.
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Affiliation(s)
- Dana C Walters
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA, USA
| | - Erwin E W Jansen
- Department of Clinical Chemistry, Metabolic Unit, VU University Medical Center & Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Gajja S Salomons
- Department of Clinical Chemistry, Metabolic Unit, VU University Medical Center & Amsterdam Neuroscience, Amsterdam, the Netherlands
| | - Erland Arning
- Baylor Scott & White Research Institute, Institute of Metabolic Disease, Dallas, TX, USA
| | - Paula Ashcraft
- Baylor Scott & White Research Institute, Institute of Metabolic Disease, Dallas, TX, USA
| | - Teodoro Bottiglieri
- Baylor Scott & White Research Institute, Institute of Metabolic Disease, Dallas, TX, USA
| | - Jean-Baptiste Roullet
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA, USA
| | - K Michael Gibson
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA, USA.
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Police A, Shankar VK, Murthy SN. Role of Taurine Transporter in the Retinal Uptake of Vigabatrin. AAPS PharmSciTech 2020; 21:196. [PMID: 32666325 DOI: 10.1208/s12249-020-01736-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Accepted: 06/20/2020] [Indexed: 12/18/2022] Open
Abstract
Vigabatrin (VGB) is a first-line drug used for treatment of infantile spasms. On therapeutic dose, VGB accumulates in the retina causing permanent peripheral visual field constriction. The mechanism involved in retinal accumulation of VGB is ambiguous. In the present study, mechanism of VGB transport into retina was evaluated. VGB uptake into retina was studied in vitro using human adult retinal pigment epithelial (ARPE-19) cells as a model for outer blood retinal barrier. The VGB cell uptake studies demonstrated saturation kinetics with Km value of 13.1 mM and uptake was significantly increased at pH 7.4 and hyperosmolar conditions indicating involvement of carrier-mediated Na+-Cl--dependent transporter. In the presence of taurine transporter (TauT) substrates (taurine and GABA) and inhibitor guanidinoethyl sulfonate (GES), the uptake of VGB decreased significantly demonstrating contribution of TauT. The VGB retinal levels in rats were decreased by 1.5- and 1.3-folds on chronic administration of GES and taurine, respectively. In conclusion, this study demonstrated the TauT involvement in VGB uptake and accumulation in retina.
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Moshafi MH, Ghasemshirazi S, Abiri A. The art of suicidal molecular seduction for targeting drug resistance. Med Hypotheses 2020; 140:109676. [PMID: 32203818 DOI: 10.1016/j.mehy.2020.109676] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 02/29/2020] [Accepted: 03/14/2020] [Indexed: 12/11/2022]
Abstract
The development of drug resistance is one of the most significant challenges of the current century in the pharmaceutical industry. Superinfections, cancer chemoresistance, and resistance observed in many non-infectious diseases are nullifying the efforts and monetary supplies, put in the advent of new drug molecules. Millions of people die because of this drug resistance developed gradually through extensive use of the drugs. Inherently, some drugs are less prone to become ineffective by drug resistance than others. Covalent inhibitors bind to their targets via a biologically permanent bound with their cognate receptor and therefore display more potent inhibiting characteristics. Suicide inhibitors or mechanism-based inhibitors are one of the covalent inhibitors, which require a pre-activation step by their targeting enzyme. This step accrues their selectivity and specificity with respect to other covalent inhibitors. After that pre-activation step, they produce an analogue of the transition state of the catalytic enzyme, which is practically incapable of dissociating from the enzyme. Suicide inhibitors, due to their high intrinsic affinity toward the related enzyme, are resistant to many mechanisms involved in the development of drug resistance and can be regarded as one of the enemies of this scientific hurdle. These inhibitors compete even with monoclonal antibodies in terms of their cost-effectiveness and efficacy.
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Affiliation(s)
- Mohammad Hassan Moshafi
- Pharmaceutics Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran
| | - Saeid Ghasemshirazi
- Department of Computer Engineering, Shahid Bahonar University of Kerman, Kerman, Iran
| | - Ardavan Abiri
- Department of Medicinal Chemistry, Faculty of Pharmacy, Kerman University of Medical Sciences, Kerman, Iran.
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Chan K, Hoon M, Pattnaik BR, Ver Hoeve JN, Wahlgren B, Gloe S, Williams J, Wetherbee B, Kiland JA, Vogel KR, Jansen E, Salomons G, Walters D, Roullet JB, Gibson K M, McLellan GJ. Vigabatrin-Induced Retinal Functional Alterations and Second-Order Neuron Plasticity in C57BL/6J Mice. Invest Ophthalmol Vis Sci 2020; 61:17. [PMID: 32053727 PMCID: PMC7326505 DOI: 10.1167/iovs.61.2.17] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 11/07/2019] [Indexed: 12/13/2022] Open
Abstract
Purpose Vigabatrin (VGB) is an effective antiepileptic that increases concentrations of inhibitory γ-aminobutyric acid (GABA) by inhibiting GABA transaminase. Reports of VGB-associated visual field loss limit its clinical usefulness, and retinal toxicity studies in laboratory animals have yielded conflicting results. Methods We examined the functional and morphologic effects of VGB in C57BL/6J mice that received either VGB or saline IP from 10 to 18 weeks of age. Retinal structure and function were assessed in vivo by optical coherence tomography (OCT), ERG, and optomotor response. After euthanasia, retinas were processed for immunohistochemistry, and retinal GABA, and VGB quantified by mass spectrometry. Results No significant differences in visual acuity or total retinal thickness were identified between groups by optomotor response or optical coherence tomography, respectively. After 4 weeks of VGB treatment, ERG b-wave amplitude was enhanced, and amplitudes of oscillatory potentials were reduced. Dramatic rod and cone bipolar and horizontal cell remodeling, with extension of dendrites into the outer nuclear layer, was observed in retinas of VGB-treated mice. VGB treatment resulted in a mean 3.3-fold increase in retinal GABA concentration relative to controls and retinal VGB concentrations that were 20-fold greater than brain. Conclusions No evidence of significant retinal thinning or ERG a- or b-wave deficits were apparent, although we describe significant alterations in ERG b-wave and oscillatory potentials and in retinal cell morphology in VGB-treated C57BL/6J mice. The dramatic concentration of VGB in retina relative to the target tissue (brain), with a corresponding increase in retinal GABA, offers insight into the pathophysiology of VGB-associated visual field loss.
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Affiliation(s)
- Kore Chan
- Department of Ophthalmology & Visual Science, University of Wisconsin–Madison, Madison, Wisconsin, United States
- McPherson Eye Research Institute, Madison, Wisconsin, United States
| | - Mrinalini Hoon
- Department of Ophthalmology & Visual Science, University of Wisconsin–Madison, Madison, Wisconsin, United States
- McPherson Eye Research Institute, Madison, Wisconsin, United States
| | - Bikash R. Pattnaik
- McPherson Eye Research Institute, Madison, Wisconsin, United States
- Pediatrics Ophthalmology & Visual Science, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - James N. Ver Hoeve
- Department of Ophthalmology & Visual Science, University of Wisconsin–Madison, Madison, Wisconsin, United States
- McPherson Eye Research Institute, Madison, Wisconsin, United States
| | - Brad Wahlgren
- Department of Ophthalmology & Visual Science, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Shawna Gloe
- Department of Ophthalmology & Visual Science, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Jeremy Williams
- Department of Ophthalmology & Visual Science, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Brenna Wetherbee
- Department of Ophthalmology & Visual Science, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Julie A. Kiland
- Department of Ophthalmology & Visual Science, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Kara R. Vogel
- Department of Ophthalmology & Visual Science, University of Wisconsin–Madison, Madison, Wisconsin, United States
- McPherson Eye Research Institute, Madison, Wisconsin, United States
| | - Erwin Jansen
- Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Gajja Salomons
- Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Dana Walters
- Washington State University College of Pharmacy and Pharmaceutical Sciences, Spokane, Washington, United States
| | - Jean-Baptiste Roullet
- Washington State University College of Pharmacy and Pharmaceutical Sciences, Spokane, Washington, United States
| | - K Michael Gibson
- Washington State University College of Pharmacy and Pharmaceutical Sciences, Spokane, Washington, United States
| | - Gillian J. McLellan
- Department of Ophthalmology & Visual Science, University of Wisconsin–Madison, Madison, Wisconsin, United States
- Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin–Madison, Madison, Wisconsin, United States
- McPherson Eye Research Institute, Madison, Wisconsin, United States
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Walters DC, Arning E, Bottiglieri T, Jansen EEW, Salomons GS, Brown MN, Schmidt MA, Ainslie GR, Roullet JB, Gibson KM. Metabolomic analyses of vigabatrin (VGB)-treated mice: GABA-transaminase inhibition significantly alters amino acid profiles in murine neural and non-neural tissues. Neurochem Int 2019; 125:151-162. [PMID: 30822440 DOI: 10.1016/j.neuint.2019.02.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 02/19/2019] [Accepted: 02/20/2019] [Indexed: 11/18/2022]
Abstract
The anticonvulsant vigabatrin (VGB; SabrilR) irreversibly inhibits GABA transaminase to increase neural GABA, yet its mechanism of retinal toxicity remains unclear. VGB is suggested to alter several amino acids, including homocarnosine, β-alanine, ornithine, glycine, taurine, and 2-aminoadipic acid (AADA), the latter a homologue of glutamic acid. Here, we evaluate the effect of VGB on amino acid concentrations in mice, employing a continuous VGB infusion (subcutaneously implanted osmotic minipumps), dose-escalation paradigm (35-140 mg/kg/d, 12 days), and amino acid quantitation in eye, visual and prefrontal cortex, total brain, liver and plasma. We hypothesized that continuous VGB dosing would reveal numerous hitherto undescribed amino acid disturbances. Consistent amino acid elevations across tissues included GABA, β-alanine, carnosine, ornithine and AADA, as well as neuroactive aspartic and glutamic acids, serine and glycine. Maximal increase of AADA in eye occurred at 35 mg/kg/d (41 ± 2 nmol/g (n = 21, vehicle) to 60 ± 8.5 (n = 8)), and at 70 mg/kg/d for brain (97 ± 6 (n = 21) to 145 ± 6 (n = 6)), visual cortex (128 ± 6 to 215 ± 19) and prefrontal cortex (124 ± 11 to 200 ± 13; mean ± SEM; p < 0.05), the first demonstration of tissue AADA accumulation with VGB in mammal. VGB effects on basic amino acids, including guanidino-species, suggested the capacity of VGB to alter urea cycle function and nitrogen disposal. The known toxicity of AADA in retinal glial cells highlights new avenues for assessing VGB retinal toxicity and other off-target effects.
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Affiliation(s)
- Dana C Walters
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA, USA
| | - Erland Arning
- Baylor Scott & White Research Institute, Institute of Metabolic Disease, Dallas, TX, USA
| | - Teodoro Bottiglieri
- Baylor Scott & White Research Institute, Institute of Metabolic Disease, Dallas, TX, USA
| | - Erwin E W Jansen
- Metabolic Laboratory, Department of Clinical Chemistry, Amsterdam University Medical Center, the Netherlands
| | - Gajja S Salomons
- Metabolic Laboratory, Department of Clinical Chemistry, Amsterdam University Medical Center, the Netherlands
| | - Madalyn N Brown
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA, USA
| | - Michelle A Schmidt
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA, USA
| | - Garrett R Ainslie
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA, USA
| | - Jean-Baptiste Roullet
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA, USA
| | - K Michael Gibson
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA, USA.
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Spelbrink EM, Mabud TS, Reimer R, Porter BE. Plasma taurine levels are not affected by vigabatrin in pediatric patients. Epilepsia 2016; 57:e168-72. [PMID: 27344989 DOI: 10.1111/epi.13447] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/26/2016] [Indexed: 11/29/2022]
Abstract
Vigabatrin is a highly effective antiseizure medication, but its use is limited due to concerns about retinal toxicity. One proposed mechanism for this toxicity is vigabatrin-mediated reduction of taurine. Herein we assess plasma taurine levels in a retrospective cohort of children with epilepsy, including a subset receiving vigabatrin. All children who underwent a plasma amino acid analysis as part of their clinical evaluation between 2006 and 2015 at Stanford Children's Health were included in the analysis. There were no significant differences in plasma taurine levels between children taking vigabatrin (n = 16), children taking other anti-seizure medications, and children not taking any anti-seizure medication (n = 556) (analysis of variance [ANOVA] p = 0.841). There were, however, age-dependent decreases in plasma taurine levels. Multiple linear regression revealed no significant association between vigabatrin use and plasma taurine level (p = 0.87) when controlling for age. These results suggest that children taking vigabatrin maintain normal plasma taurine levels, although they leave unanswered whether taurine supplementation is necessary or sufficient to prevent vigabatrin-associated visual field loss. They also indicate that age should be taken into consideration when evaluating taurine levels in young children.
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Affiliation(s)
- Emily M Spelbrink
- Department of Neurology, Stanford University School of Medicine, Stanford, California, U.S.A.,Department of Neurology, Stanford Children's Health, Palo Alto, California, U.S.A
| | - Tarub S Mabud
- Department of Neurology, Stanford University School of Medicine, Stanford, California, U.S.A
| | - Richard Reimer
- Department of Neurology, Stanford University School of Medicine, Stanford, California, U.S.A
| | - Brenda E Porter
- Department of Neurology, Stanford University School of Medicine, Stanford, California, U.S.A.,Department of Neurology, Stanford Children's Health, Palo Alto, California, U.S.A
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Cavero I. 14th Annual Meeting of the Safety Pharmacology Society: threading through scientific sessions for originality and novelty. Expert Opin Drug Saf 2015; 14:999-1008. [DOI: 10.1517/14740338.2015.1034104] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Akula JD, Noonan ER, Di Nardo A, Favazza TL, Zhang N, Sahin M, Hansen RM, Fulton AB. Vigabatrin can enhance electroretinographic responses in pigmented and albino rats. Doc Ophthalmol 2015; 131:1-11. [PMID: 25761928 DOI: 10.1007/s10633-015-9491-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 02/23/2015] [Indexed: 11/26/2022]
Abstract
PURPOSE To evaluate the effects of the antiepileptic medication vigabatrin (VGB) on the retina of pigmented rats. METHODS Scotopic and photopic electroretinograms were recorded from dark- and light-adapted Long-Evans (pigmented) and Sprague Dawley (albino) rats administered, daily, 52-55 injections of 250 mg·kg(-1)·day(-1) VGB or 25-26 injections of 500 mg·kg(-1)·day(-1) VGB, or a corresponding number of sham injections. Sensitivity and saturated amplitude of the rod photoresponse (S, Rm(P3)) and postreceptor response (1/σ, Vm) were derived, as were sensitivity and amplitude of the cone-mediated postreceptor response (1/σ(cone), Vm(cone)). The oscillatory potentials and responses to a series of flickering lights (6.25, 12.5, 25 and 50 Hz) were studied in the time and frequency domains. A subset of rats' eyes was harvested for Western blotting or histology. RESULTS Of the parameters derived from dark-adapted ERG responses, in both pigmented and albino rats, VGB repeatedly and reliably enhanced electroretinographic parameters; no significant ERG deficits were noted. No significant alterations were observed in ER/oxidative stress or in the Akt cell death/survival pathway. There were migrations of photoreceptor nuclei toward the RPE and outgrowths of bipolar cell dendrites into the outer nuclear layer in VGB-treated rats; these were never observed in sham-treated animals. CONCLUSIONS Although VGB is associated with retinal dysfunction in patients and VGB toxicity has been demonstrated by other laboratories in the albino rat, in our pigmented and albino rats, VGB did not induce deficits in, but rather enhanced, retinal function. Nonetheless, retinal neuronal dysplasia was observed.
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