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Liu R, Sun L, Wang Y, Wang Q, Wu J. New use for an old drug: quinidine in KCNT1-related epilepsy therapy. Neurol Sci 2023; 44:1201-1206. [PMID: 36437393 DOI: 10.1007/s10072-022-06521-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 11/18/2022] [Indexed: 11/29/2022]
Abstract
KCNT1 has been known to encode a subunit of the tetrameric sodium activated potassium channel (KNa1.1). Pathogenic variants of KCNT1, especially gain-of-function (GOF) variants, are associated with multiple epileptic disorders which are often refractory to conventional anti-seizure medications and summarized as KCNT1-related epilepsy. Although the detailed pathogenic mechanisms of KCNT1-related epilepsy remain unknown, increasing studies attempt to find effective medications for those patients by utilizing quinidine to inhibit hyperexcitable KNa1.1. However, it has been shown that controversial outcomes among studies and partial success in some individuals may be due to multiple factors, such as poor blood-brain barrier (BBB) penetration, mutation-dependent manner, phenotype-genotype associations, and rational therapeutic schedule. In recent years, with higher resolution of KNa1.1 structure in different activation states and advanced synthetic techniques, it improves the process performance of therapy targeting at KNa1.1 channel to achieve more effective outcomes. Here, we systematically reviewed the study history of quinidine on KCNT1-related epilepsy and its corresponding therapeutic effects. Then, we analyzed and summarized the possible causes behind the different outcomes of the application of quinidine. Finally, we outlooked the recent advances in precision medicine treatment for KCNT1-related epilepsy.
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Affiliation(s)
- Ru Liu
- Hubei Key Laboratory of Nanomedicine for Neurodegenerative Diseases, School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, 122 Loushi Rd, Wuhan, 430070, China
- Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, 100070, China
| | - Lei Sun
- Department of Neurology, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Henan University People's Hospital, Zhengzhou, 450008, Henan, China
| | - Yunfu Wang
- Hubei Key Laboratory of Embryonic Stem Cell Research, Hubei University of Medicine, Shiyan, 442000, China
| | - Qun Wang
- Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, 100070, China
| | - Jianping Wu
- Hubei Key Laboratory of Nanomedicine for Neurodegenerative Diseases, School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, 122 Loushi Rd, Wuhan, 430070, China.
- Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China.
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, 100070, China.
- China National Clinical Research Center for Neurological Diseases, Beijing, 100070, China.
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2
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Regional Differences in the Absolute Abundance of Transporters, Receptors and Tight Junction Molecules at the Blood-Arachnoid Barrier and Blood-Spinal Cord Barrier among Cervical, Thoracic and Lumbar Spines in Dogs. Pharm Res 2022; 39:1393-1413. [PMID: 35488144 DOI: 10.1007/s11095-022-03275-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 04/25/2022] [Indexed: 10/18/2022]
Abstract
PURPOSE The purpose of the present study was to quantitatively determine the expression of transporters, receptors and tight junction molecules at the blood-arachnoid barrier (BAB) and blood-spinal cord barrier (BSCB) in cervical, thoracic and lumbar spines from dogs. METHODS The expression levels of 31 transporters, 3 receptors, 1 tight junction protein, and 3 marker proteins in leptomeninges and capillaries isolated from spines (3 male and 2 female dogs) were determined by quantitative Targeted Absolute Proteomics (qTAP). The units were converted from fmol/μg protein to pmol/cm (absolute abundance at the BAB and the BSCB in a 1 cm section of spine). RESULTS The expression of MDR1 and BCRP were greater at the BSCB compared to the BAB (especially in the cervical cord), and the expressions at the lumbar BSCB were lower than that for the cervical BSCB. Among the organic anionic and cationic drug transporters, OAT1, OAT3, MRP1, OCT2 and MATE1/2 were detected only in the BAB, and not at the BSCB). The expression of these transporters was higher in the order: lumbar > thoracic > cervical BAB. The expressions of GLUT1, 4F2hc, EAAT1, 2, PEPT2, CTL1, and MCT1 at the BSCB of the cervical cord were higher than the corresponding values for the cervical BAB, and these values decreased in going down the spinal cord. CONCLUSION These results provide a better understanding of the molecular mechanisms underlying the concentration gradients of drugs and endogenous substances in the cerebrospinal fluid and parenchyma of the spinal cord.
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3
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Uchida Y, Takeuchi H, Goto R, Braun C, Fuchs H, Ishiguro N, Takao M, Tano M, Terasaki T. A Human Blood‐Arachnoid Barrier Atlas of Transporters, Receptors, Enzymes, Tight Junction and Marker Proteins: Comparison with Dog and Pig in Absolute Abundance. J Neurochem 2022; 161:187-208. [DOI: 10.1111/jnc.15599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 02/17/2022] [Accepted: 02/21/2022] [Indexed: 11/29/2022]
Affiliation(s)
- Yasuo Uchida
- Graduate School of Pharmaceutical Sciences Tohoku University Japan
- Faculty of Pharmaceutical Sciences Tohoku University Japan
| | - Hina Takeuchi
- Graduate School of Pharmaceutical Sciences Tohoku University Japan
| | - Ryohei Goto
- Faculty of Pharmaceutical Sciences Tohoku University Japan
| | - Clemens Braun
- Boehringer Ingelheim Pharma GmbH & Co. KG, Drug Discovery Sciences Germany
| | - Holger Fuchs
- Boehringer Ingelheim Pharma GmbH & Co. KG, Cardio‐metabolic Diseases Germany
| | | | - Masaki Takao
- Department of Neurology and Brain Bank Mihara Memorial Hospital Japan
- Department of Clinical Laboratory, National Center of Neurology and Psychiatry, National Center Hospital Japan
| | - Mitsutoshi Tano
- Department of Neurology and Brain Bank Mihara Memorial Hospital Japan
| | - Tetsuya Terasaki
- Graduate School of Pharmaceutical Sciences Tohoku University Japan
- Faculty of Pharmaceutical Sciences Tohoku University Japan
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Differences in P-glycoprotein activity in human and rodent blood-brain barrier assessed by mechanistic modelling. Arch Toxicol 2021; 95:3015-3029. [PMID: 34268580 PMCID: PMC8380243 DOI: 10.1007/s00204-021-03115-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 06/29/2021] [Indexed: 12/28/2022]
Abstract
Variation in the efficacy and safety of central nervous system drugs between humans and rodents can be explained by physiological differences between species. An important factor could be P-glycoprotein (Pgp) activity in the blood–brain barrier (BBB), as BBB expression of this drug efflux transporter is reportedly lower in humans compared to mouse and rat and subject to an age-dependent increase. This might complicate animal to human extrapolation of brain drug disposition and toxicity, especially in children. In this study, the potential species-specific effect of BBB Pgp activity on brain drug exposure was investigated. An age-dependent brain PBPK model was used to predict cerebrospinal fluid and brain mass concentrations of Pgp substrate drugs. For digoxin, verapamil and quinidine, in vitro kinetic data on their transport by Pgp were derived from literature and used to scale to in vivo parameters. In addition, age-specific digoxin transport was simulated for children with a postnatal age between 25 and 81 days. BBB Pgp activity in the model was optimized using measured CSF data for the Pgp substrates ivermectin, indinavir, vincristine, docetaxel, paclitaxel, olanzapine and citalopram, as no useful in vitro data were available. Inclusion of Pgp activity in the model resulted in optimized predictions of their brain concentration. Total brain-to-plasma AUC values (Kp,brain) in the simulations without Pgp were divided by the Kp,brain values with Pgp. Kp ratios ranged from 1 to 45 for the substrates investigated. Comparison of human with rodent Kp,brain ratios indicated ≥ twofold lower values in human for digoxin, verapamil, indinavir, paclitaxel and citalopram and ≥ twofold higher values for vincristine. In conclusion, BBB Pgp activity appears species-specific. An age-dependent PBPK model-based approach could be useful to extrapolate animal data to human adult and paediatric predictions by taking into account species-specific and developmental BBB Pgp expression.
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Abstract
Genetic testing has yielded major advances in our understanding of the causes of epilepsy. Seizures remain resistant to treatment in a significant proportion of cases, particularly in severe, childhood-onset epilepsy, the patient population in which an underlying causative genetic variant is most likely to be identified. A genetic diagnosis can be explanatory as to etiology, and, in some cases, might suggest a therapeutic approach; yet, a clear path from genetic diagnosis to treatment remains unclear in most cases. Here, we discuss theoretical considerations behind the attempted use of small molecules for the treatment of genetic epilepsies, which is but one among various approaches currently under development. We explore a few salient examples and consider the future of the small molecule approach for genetic epilepsies. We conclude that significant additional work is required to understand how genetic variation leads to dysfunction of epilepsy-associated protein targets, and how this impacts the function of diverse subtypes of neurons embedded within distributed brain circuits to yield epilepsy and epilepsy-associated comorbidities. A syndrome- or even variant-specific approach may be required to achieve progress. Advances in the field will require improved methods for large-scale target validation, compound identification and optimization, and the development of accurate model systems that reflect the core features of human epilepsy syndromes, as well as novel approaches towards clinical trials of such compounds in small rare disease cohorts.
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Affiliation(s)
- Ethan M Goldberg
- Department of Pediatrics, Division of Neurology, Abramson Research Center, The Epilepsy Neurogenetics Initiative, The Children's Hospital of Philadelphia, Abramson Research Center Room 502A, 19104, Philadelphia, PA, USA.
- Departments of Neurology and Neuroscience, The University of Pennsylvania Perelman School of Medicine, 19104, Philadelphia, PA, USA.
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6
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Cole BA, Clapcote SJ, Muench SP, Lippiat JD. Targeting K Na1.1 channels in KCNT1-associated epilepsy. Trends Pharmacol Sci 2021; 42:700-713. [PMID: 34074526 DOI: 10.1016/j.tips.2021.05.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 04/30/2021] [Accepted: 05/05/2021] [Indexed: 12/19/2022]
Abstract
Gain-of-function (GOF) pathogenic variants of KCNT1, the gene encoding the largest known potassium channel subunit, KNa1.1, are associated with developmental and epileptic encephalopathies accompanied by severe psychomotor and intellectual disabilities. Blocking hyperexcitable KNa1.1 channels with quinidine, a class I antiarrhythmic drug, has shown variable success in patients in part because of dose-limiting off-target effects, poor blood-brain barrier (BBB) penetration, and low potency. In recent years, high-resolution cryogenic electron microscopy (cryo-EM) structures of the chicken KNa1.1 channel in different activation states have been determined, and animal models of the diseases have been generated. Alongside increasing information about the functional effects of GOF pathogenic variants on KNa1.1 channel behaviour and how they lead to hyperexcitability, these tools will facilitate the development of more effective treatment strategies. We review the range of KCNT1 variants and their functional effects, the challenges posed by current treatment strategies, and recent advances in finding more potent and selective therapeutic interventions for KCNT1-related epilepsies.
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Affiliation(s)
- Bethan A Cole
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Steven J Clapcote
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Stephen P Muench
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
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Kravetz MC, Viola MS, Prenz J, Curi M, Bramuglia GF, Tenembaum S. Case Report of Novel Genetic Variant in KCNT1 Channel and Pharmacological Treatment With Quinidine. Precision Medicine in Refractory Epilepsy. Front Pharmacol 2021; 12:648519. [PMID: 34122071 PMCID: PMC8194824 DOI: 10.3389/fphar.2021.648519] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 03/26/2021] [Indexed: 11/16/2022] Open
Abstract
Case introduction: In this work we present a female infant patient with epilepsy of infancy with migrating focal seizures (EIMFS). Although many pharmacological schemes were attempted, she developed an encephalopathy with poor response to antiepileptic drugs and progressive cerebral dysfunction. Aim: To present the pharmacological response and therapeutic drug monitoring of a paediatric patient with a severe encephalopathy carrying a genetic variant in KCNT1 gene, whose identification led to include quinidine (QND) in the treatment regimen as an antiepileptic drug. Case report: Patient showed slow rhythmic activity (theta range) over left occipital areas with temporal propagation and oculo-clonic focal seizures and without tonic spasms three months after birth. At the age of 18 months showed severe impairments of motor and intellectual function with poor eye contact. When the patient was 4 years old, a genetic variant in the exon 24 of the KCNT1 gene was found. This led to the diagnosis of EIMFS. Due to antiepileptic treatment failed to control seizures, QND a KCNT1 blocker, was introduced as a therapeutic alternative besides topiramate (200 mg/day) and nitrazepam (2 mg/day). Therapeutic drug monitoring (TDM) of QND plasma levels needed to be implemented to establish individual therapeutic range and avoid toxicity. TDM for dose adjustment was performed to establish the individual therapeutic range of the patient. Seizures were under control with QND levels above 1.5 mcg/ml (65–70 mg/kg q. i.d). In addition, QND levels higher than 4.0 mcg/ml, were related to higher risk of suffering arrhythmia due to prolongation of QT segment. Despite initial intention to withdrawal topiramate completely, QND was no longer effective by itself and failed to maintain seizures control. Due to this necessary interaction between quinidine and topiramate, topiramate was stablished in a maintenance dose of 40 mg/day. Conclusion: The implementation of Precision Medicine by using tools such as Next Generation Sequencing and TDM led to diagnose and select a targeted therapy for the treatment of a KCNT1-related epilepsy in a patient presented with EIMFS in early infancy and poor response to antiepileptic drugs. QND an old antiarrhythmic drug, due to its activity as KCNT1 channel blocker, associated to topiramate resulted in seizures control. Due to high variability observed in QND levels, TDM and pharmacokinetic characterization allowed to optimize drug regimen to maintain QND concentration between the individual therapeutic range and diminish toxicity.
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Affiliation(s)
- M C Kravetz
- Department of Pharmacology, Faculty of Farmacy and Biochemistry, University of Buenos Aires, Buenos Aires City, Argentina
| | - M S Viola
- Department of Pharmacology, Faculty of Farmacy and Biochemistry, University of Buenos Aires, Buenos Aires City, Argentina
| | - J Prenz
- Department of Cardiology, Garrahan Hospital, Buenos Aires City, Argentina
| | - M Curi
- Department of Cardiology, Garrahan Hospital, Buenos Aires City, Argentina
| | - G F Bramuglia
- Department of Pharmacology, Faculty of Farmacy and Biochemistry, University of Buenos Aires, Buenos Aires City, Argentina.,Fundacion Investigar, Buenos Aires City, Argentina
| | - S Tenembaum
- Department of Neurology, Garrahan Hospital, Buenos Aires City, Argentina
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Venti V, Ciccia L, Scalia B, Sciuto L, Cimino C, Marino S, Praticò AD, Falsaperla R. KCNT1-Related Epilepsy: A Review. JOURNAL OF PEDIATRIC NEUROLOGY 2021. [DOI: 10.1055/s-0041-1728688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Abstract
KCNT1 gene encodes the sodium-dependent potassium channel reported as a causal factor for several different epileptic disorders. The gene has been also linked with cardiac disorders and in a family to sudden unexpected death in epilepsy. KCNT1 mutations, in most cases, result in a gain of function causing a neuronal hyperpolarization with loss of inhibition. Many early-onset epileptic encephalopathies related to gain of function of KCNT1 gene have been described, most often associated with two phenotypes: malignant migrating focal seizures of infancy and familial autosomal-dominant nocturnal frontal lobe epilepsy; however, there is no clear phenotype–genotype correlation, in fact same mutations have been represented in patients with West syndrome, Ohtahara syndrome, and early myoclonic encephalopathy. Additional neurologic features include intellectual disability, psychiatric disorders, hypotonia, microcephaly, strabismus, and movement disorders. Conventional anticonvulsant, vagal stimulation, and ketogenic diet have been used in the absence of clinical benefit in individuals with KCNT1-related epilepsy; in some patients, quinidine therapy off-label has been practiced successfully. This review aims to describe the characteristics of the gene, the phenotypes related to genetic mutations with the possible genotype–phenotype correlations and the treatments proposed to date, discussing the comorbidities reported in the literature.
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Affiliation(s)
- Valeria Venti
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Lina Ciccia
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Bruna Scalia
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Laura Sciuto
- Pediatrics Postgraduate Residency Program, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Carla Cimino
- Unit of Pediatrics and Pediatric Emergency, University Hospital “Policlinico Rodolico-San Marco,” Catania, Italy
| | - Simona Marino
- Unit of Neonatal Intensive Care and Neonatology, University Hospital “Policlinico Rodolico-San Marco,” Catania, Italy
| | - Andrea D. Praticò
- Unit of Rare Diseases of the Nervous System in Childhood, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Raffaele Falsaperla
- Unit of Pediatrics and Pediatric Emergency, University Hospital “Policlinico Rodolico-San Marco,” Catania, Italy
- Unit of Neonatal Intensive Care and Neonatology, University Hospital “Policlinico Rodolico-San Marco,” Catania, Italy
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9
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Fitzgerald MP, Fiannacca M, Smith DM, Gertler TS, Gunning B, Syrbe S, Verbeek N, Stamberger H, Weckhuysen S, Ceulemans B, Schoonjans AS, Rossi M, Demarquay G, Lesca G, Olofsson K, Koolen DA, Hornemann F, Baulac S, Rubboli G, Minks KQ, Lee B, Helbig I, Dlugos D, Møller RS, Bearden D. Treatment Responsiveness in KCNT1-Related Epilepsy. Neurotherapeutics 2019; 16:848-857. [PMID: 31054119 PMCID: PMC6694367 DOI: 10.1007/s13311-019-00739-y] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Pathogenic variants in KCNT1 represent an important cause of treatment-resistant epilepsy, for which an effective therapy has been elusive. Reports about the effectiveness of quinidine, a candidate precision therapy, have been mixed. We sought to evaluate the treatment responsiveness of patients with KCNT1-related epilepsy. We performed an observational study of 43 patients using a collaborative KCNT1 patient registry. We assessed treatment efficacy based upon clinical seizure reduction, side effects of quinidine therapy, and variant-specific responsiveness to treatment. Quinidine treatment resulted in a > 50% seizure reduction in 20% of patients, with rare patients achieving transient seizure freedom. Multiple other therapies demonstrated some success in reducing seizure frequency, including the ketogenic diet and vigabatrin, the latter particularly in patients with epileptic spasms. Patients with the best quinidine response had variants that clustered distal to the NADP domain within the RCK2 domain of the protein. Half of patients did not receive a quinidine trial. In those who did, nearly half did not achieve therapeutic blood levels. More favorable response to quinidine in patients with KCNT1 variants distal to the NADP domain within the RCK2 domain may suggest a variant-specific response.
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Affiliation(s)
- Mark P Fitzgerald
- Division of Neurology, Departments of Neurology and Pediatrics, The Children's Hospital of Philadelphia and the Perelman School of Medicine at the University of Pennsylvania, 3501 Civic Center Blvd, Philadelphia, PA, 19104, USA.
| | | | | | - Tracy S Gertler
- Division of Neurology, Department of Pediatrics, Ann and Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
| | - Boudewijn Gunning
- Stichting Epilepsie Instellingen Nederland, Zwolle, 8025 BV, Netherlands
| | - Steffen Syrbe
- Division of Child Neurology and Inherited Metabolic Diseases, Department of General Paediatrics, Centre for Paediatrics and Adolescent Medicine, University Hospital Heidelberg, Im Neuenheimer Feld 430, 69120, Heidelberg, Germany
| | - Nienke Verbeek
- Department of Genetics, University Medical Center Utrecht, Utrecht, 3584 CX, The Netherlands
| | - Hannah Stamberger
- Neurogenetics group, Center for Molecular Neurology, Vlaams Instituut voor Biotechnologie, and Institute Born Bunge, University of Antwerp, Antwerp, 2000, Belgium
- Department of Neurology, Antwerp University Hospital, Antwerp, 2650, Belgium
| | - Sarah Weckhuysen
- Neurogenetics group, Center for Molecular Neurology, Vlaams Instituut voor Biotechnologie, and Institute Born Bunge, University of Antwerp, Antwerp, 2000, Belgium
- Department of Neurology, Antwerp University Hospital, Antwerp, 2650, Belgium
| | - Berten Ceulemans
- Department of Paediatric Neurology, Antwerp University Hospital, University of Antwerp, Antwerp, 2650, Belgium
| | - An-Sofie Schoonjans
- Neurogenetics Research Group, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZ Brussel), Laarbeeklaan 101, 1090, Brussels, Belgium
| | - Massimiliano Rossi
- Genetics department, Hospices Civils de Lyon, and Institut National de la Santé et de la Recherche Médicale U1028, Centre national de la recherche scientifique Unité Mixte de Recherche 5292, Lyon Neuroscience Research Center, GENDEV Team, Claude Bernard Lyon 1 University, Bron, 69500, France
| | - Geneviève Demarquay
- Department of Functional Neurology and Epileptology, Hospices Civils de Lyon and Centre national de la recherche scientifique, Unité Mixte de Recherche 5292, Lyon Neuroscience Research Center, Auditory Cognition and Psychoacoustics Team, Lyon, 69003, France
| | - Gaetan Lesca
- Genetics department, Hospices Civils de Lyon, and Institut National de la Santé et de la Recherche Médicale U1028, Centre national de la recherche scientifique Unité Mixte de Recherche 5292, Lyon Neuroscience Research Center, GENDEV Team, Claude Bernard Lyon 1 University, Bron, 69500, France
| | - Kern Olofsson
- Danish Epilepsy Centre, Filadelfia, Dianalund,, DK 4293, Denmark
| | - D A Koolen
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, 6525 GA, The Netherlands
| | - Frauke Hornemann
- Centre of Pediatric Research, Hospital for Children and Adolescents, 04103, Leipzig, Germany
| | - Stephanie Baulac
- Sorbonne Université, UPMC Univ Paris 06, Unité Mixte de Recherche S 1127, F-75013, Paris, France
- Institut National de la Santé et de la Recherche Médicale, U1127, F-75013, Paris, France
- Centre national de la recherche scientifique, Unité Mixte de Recherche 7225, F-75013, Paris, France
- Institut du Cerveau et de la Moelle épinière (ICM), Hôpital Pitié-Salpêtrière, F-75013, Paris, France
- Department of Genetics, Assistance Publique des Hôpitaux de Paris (AP-HP), Hôpital Pitié-Salpêtrière, F-75013, Paris, France
| | - Guido Rubboli
- Danish Epilepsy Centre, Filadelfia, Dianalund,, DK 4293, Denmark
- University of Copenhagen, Copenhagen, 1165, Denmark
| | - Kelly Q Minks
- Division of Child Neurology, Department of Neurology, University of Rochester School of Medicine, Rochester, NY, USA
| | - Bohoon Lee
- Division of Child Neurology, Department of Neurology, University of Rochester School of Medicine, Rochester, NY, USA
| | - Ingo Helbig
- Division of Neurology, Departments of Neurology and Pediatrics, The Children's Hospital of Philadelphia and the Perelman School of Medicine at the University of Pennsylvania, 3501 Civic Center Blvd, Philadelphia, PA, 19104, USA
| | - Dennis Dlugos
- Division of Neurology, Departments of Neurology and Pediatrics, The Children's Hospital of Philadelphia and the Perelman School of Medicine at the University of Pennsylvania, 3501 Civic Center Blvd, Philadelphia, PA, 19104, USA
| | - Rikke S Møller
- Danish Epilepsy Centre, Filadelfia, Dianalund,, DK 4293, Denmark
- Institute for Regional Health Research, University of Southern Denmark, Odense, 5230, Denmark
| | - David Bearden
- Division of Child Neurology, Department of Neurology, University of Rochester School of Medicine, Rochester, NY, USA
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10
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Numis AL, Nair U, Datta AN, Sands TT, Oldham MS, Patel A, Li M, Gazina E, Petrou S, Cilio MR. Lack of response to quinidine in KCNT1
-related neonatal epilepsy. Epilepsia 2018; 59:1889-1898. [DOI: 10.1111/epi.14551] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 07/31/2018] [Accepted: 08/01/2018] [Indexed: 12/22/2022]
Affiliation(s)
- Adam L. Numis
- Department of Neurology; University of California San Francisco; San Francisco California
- Department of Pediatrics; University of California San Francisco; San Francisco California
| | - Umesh Nair
- The Florey Institute of Neuroscience & Mental Health; Parkville Victoria Australia
| | - Anita N. Datta
- Department of Pediatrics; University of British Columbia; Vancouver British Columbia Canada
| | | | - Michael S. Oldham
- Department of Neurology; University of California San Francisco; San Francisco California
| | - Akash Patel
- Department of Pediatrics; University of California San Francisco; San Francisco California
| | - Melody Li
- The Florey Institute of Neuroscience & Mental Health; Parkville Victoria Australia
| | - Elena Gazina
- The Florey Institute of Neuroscience & Mental Health; Parkville Victoria Australia
| | - Steven Petrou
- The Florey Institute of Neuroscience & Mental Health; Parkville Victoria Australia
| | - Maria Roberta Cilio
- Department of Neurology; University of California San Francisco; San Francisco California
- Department of Pediatrics; University of California San Francisco; San Francisco California
- Institute of Human Genetics; University of California San Francisco; San Francisco California
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11
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Mullen SA, Carney PW, Roten A, Ching M, Lightfoot PA, Churilov L, Nair U, Li M, Berkovic SF, Petrou S, Scheffer IE. Precision therapy for epilepsy due to KCNT1 mutations. Neurology 2017; 90:e67-e72. [DOI: 10.1212/wnl.0000000000004769] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Accepted: 09/15/2017] [Indexed: 11/15/2022] Open
Abstract
ObjectiveTo evaluate quinidine as a precision therapy for severe epilepsy due to gain of function mutations in the potassium channel gene KCNT1.MethodsA single-center, inpatient, order-randomized, blinded, placebo-controlled, crossover trial of oral quinidine included 6 patients with severe autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) due to KCNT1 mutation. Order was block randomized and blinded. Four-day treatment blocks were used with a 2-day washout between. Dose started at 900 mg over 3 divided doses then, in subsequent participants, was reduced to 600 mg, then 300 mg. Primary outcome was seizure frequency measured on continuous video-EEG in those completing the trial.ResultsProlonged QT interval occurred in the first 2 patients at doses of 900 and 600 mg quinidine per day, respectively, despite serum quinidine levels well below the therapeutic range (0.61 and 0.51 μg/mL, reference range 1.3–5.0 μg/mL). Four patients completed treatment with 300 mg/d without adverse events. Patients completing the trial had very frequent seizures (mean 14 per day, SD 7, median 13, interquartile range 10–18). Seizures per day were nonsignificantly increased by quinidine (median 2, 95% confidence interval −1.5 to +5, p = 0.15) and no patient had a 50% seizure reduction.ConclusionQuinidine did not show efficacy in adults and teenagers with ADNFLE. Dose-limiting cardiac side effects were observed even in the presence of low measured serum quinidine levels. Although small, this trial suggests use of quinidine in ADNFLE is likely to be ineffective coupled with considerable cardiac risks.Clinical trials registrationAustralian Therapeutic Goods Administration Clinical Trial Registry (trial number 2015/0151).Classification of evidenceThis study provides Class II evidence that for persons with severe epilepsy due to gain of function mutations in the potassium channel gene KCNT1, quinidine does not significantly reduce seizure frequency.
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지나리, Se Hee Kim, 이준수, 강훈철, 이승태, Choi Jong Rak, 고아라, 김흥동. Quinidine Trial in a Patient with Epilepsy of Infancy with Migrating Focal Seizure and KCNT1 Mutation. ACTA ACUST UNITED AC 2017. [DOI: 10.26815/jkcns.2017.25.3.169] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Mikati MA, Jiang YH, Carboni M, Shashi V, Petrovski S, Spillmann R, Milligan CJ, Li M, Grefe A, McConkie A, Berkovic S, Scheffer I, Mullen S, Bonner M, Petrou S, Goldstein D. Quinidine in the treatment of KCNT1-positive epilepsies. Ann Neurol 2015; 78:995-9. [PMID: 26369628 DOI: 10.1002/ana.24520] [Citation(s) in RCA: 139] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Revised: 08/30/2015] [Accepted: 09/05/2015] [Indexed: 12/17/2022]
Abstract
We report 2 patients with drug-resistant epilepsy caused by KCNT1 mutations who were treated with quinidine. Both mutations manifested gain of function in vitro, showing increased current that was reduced by quinidine. One, who had epilepsy of infancy with migrating focal seizures, had 80% reduction in seizure frequency as recorded in seizure diaries, and partially validated by objective seizure evaluation on EEG. The other, who had a novel phenotype, with severe nocturnal focal and secondary generalized seizures starting in early childhood with developmental regression, did not improve. Although quinidine represents an encouraging opportunity for therapeutic benefits, our experience suggests caution in its application and supports the need to identify more targeted drugs for KCNT1 epilepsies.
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Affiliation(s)
- Mohamad A Mikati
- Division of Pediatric Neurology, Department of Pediatrics and Department of Neurobiology, Duke University School of Medicine, Durham, NC
| | - Yong-Hui Jiang
- Division of Medical Genetics, Department of Pediatrics, Duke University School of Medicine, Durham, NC
| | - Michael Carboni
- Division of Cardiology, Department of Pediatrics, Duke University School of Medicine, Durham, NC
| | - Vandana Shashi
- Division of Medical Genetics, Department of Pediatrics, Duke University School of Medicine, Durham, NC
| | - Slave Petrovski
- Center for Human Genome Variation, Duke University School of Medicine, Durham, NC
| | - Rebecca Spillmann
- Center for Human Genome Variation, Duke University School of Medicine, Durham, NC
| | - Carol J Milligan
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Melody Li
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Annette Grefe
- Department of Neurology, Wake Forest University, Winston-Salem, NC
| | - Allyn McConkie
- Division of Medical Genetics, Department of Pediatrics, Duke University School of Medicine, Durham, NC
| | - Samuel Berkovic
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - Ingrid Scheffer
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - Saul Mullen
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Melanie Bonner
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC
| | - Steven Petrou
- Epilepsy Research Centre, Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - David Goldstein
- Center for Human Genome Variation, Duke University School of Medicine, Durham, NC
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A tribute to Dr. Hermann R. Ochs, 1943-2013. J Clin Psychopharmacol 2014; 34:669-70. [PMID: 25319882 DOI: 10.1097/jcp.0000000000000241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Improving the prediction of the brain disposition for orally administered drugs using BDDCS. Adv Drug Deliv Rev 2012; 64:95-109. [PMID: 22261306 DOI: 10.1016/j.addr.2011.12.008] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Revised: 12/08/2011] [Accepted: 12/12/2011] [Indexed: 01/16/2023]
Abstract
In modeling blood-brain barrier (BBB) passage, in silico models have yielded ~80% prediction accuracy, and are currently used in early drug discovery. Being derived from molecular structural information only, these models do not take into account the biological factors responsible for the in vivo outcome. Passive permeability and P-glycoprotein (Pgp, ABCB1) efflux have been successfully recognized to impact xenobiotic extrusion from the brain, as Pgp is known to play a role in limiting the BBB penetration of oral drugs in humans. However, these two properties alone fail to explain the BBB penetration for a significant number of marketed central nervous system (CNS) agents. The Biopharmaceutics Drug Disposition Classification System (BDDCS) has proved useful in predicting drug disposition in the human body, particularly in the liver and intestine. Here we discuss the value of using BDDCS to improve BBB predictions of oral drugs. BDDCS class membership was integrated with in vitro Pgp efflux and in silico permeability data to create a simple 3-step classification tree that accurately predicted CNS disposition for more than 90% of 153 drugs in our data set. About 98% of BDDCS class 1 drugs were found to markedly distribute throughout the brain; this includes a number of BDDCS class 1 drugs shown to be Pgp substrates. This new perspective provides a further interpretation of how Pgp influences the sedative effects of H1-histamine receptor antagonists.
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Cole S, Bagal S, El-Kattan A, Fenner K, Hay T, Kempshall S, Lunn G, Varma M, Stupple P, Speed W. Full efficacy with no CNS side-effects: unachievable panacea or reality? DMPK considerations in design of drugs with limited brain penetration. Xenobiotica 2011; 42:11-27. [DOI: 10.3109/00498254.2011.617847] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Juszczak GR, Swiergiel AH. Properties of gap junction blockers and their behavioural, cognitive and electrophysiological effects: animal and human studies. Prog Neuropsychopharmacol Biol Psychiatry 2009; 33:181-98. [PMID: 19162118 DOI: 10.1016/j.pnpbp.2008.12.014] [Citation(s) in RCA: 172] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Revised: 12/22/2008] [Accepted: 12/22/2008] [Indexed: 10/21/2022]
Abstract
Gap junctions play an important role in brain physiology. They synchronize neuronal activity and connect glial cells participating in the regulation of brain metabolism and homeostasis. Gap junction blockers (GJBs) include various chemicals that impair gap junction communication, disrupt oscillatory neuronal activity over a wide range of frequencies, and decrease epileptic discharges. The behavioural and clinical effects of GJBs suggest that gap junctions can be involved in the regulation of locomotor activity, arousal, memory, and breathing. Severe neuropsychiatric side effects suggest the involvement of gap junctions in mechanisms of consciousness. Unfortunately, the available GJBs are not selective and can bind to targets other than gap junctions. Other problems in behavioural studies include the possible adverse effects of GJBs, for example, retinal toxicity and hearing disturbances, changes in blood-brain transport, and the metabolism of other drugs. Therefore, it is necessary to design experiments properly to avoid false, misleading or uninterpretable results. We review the pharmacological properties and electrophysiological, behavioural and cognitive effects of the available gap junction blockers, such as carbenoxolone, glycyrrhetinic acid, quinine, quinidine, mefloquine, heptanol, octanol, anandamide, fenamates, 2-APB, several anaesthetics, retinoic acid, oleamide, spermine, aminosulfonates, and sodium propionate. It is concluded that despite a number of different problems, the currently used gap junction blockers could be useful tools in pharmacology and neuroscience.
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Affiliation(s)
- Grzegorz R Juszczak
- Department of Animal Behaviour, Institute of Genetics and Animal Breeding, Jastrzebiec, ul. Postepu 1, 05-552 Wolka Kosowska, Poland.
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Venkatakrishnan K, Tseng E, Nelson FR, Rollema H, French JL, Kaplan IV, Horner WE, Gibbs MA. Central nervous system pharmacokinetics of the Mdr1 P-glycoprotein substrate CP-615,003: intersite differences and implications for human receptor occupancy projections from cerebrospinal fluid exposures. Drug Metab Dispos 2007; 35:1341-9. [PMID: 17470526 DOI: 10.1124/dmd.106.013953] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The central nervous system (CNS) distribution and transport mechanisms of the investigational drug candidate CP-615,003 (N-[3-fluoro-4-[2-(propylamino)ethoxy]phenyl]-4,5,6,7-tetrahydro-4-oxo-1H-indole-3-carboxamide) and its active metabolite CP-900,725 have been characterized. Brain distribution of CP-615,003 and CP-900,725 was low in rats and mice (brain-to-serum ratio < 0.2). Cerebrospinal fluid (CSF)-to-serum ratios of CP-615,003 were 6- to 8-fold lower than the plasma unbound fraction in rats and dogs. In vitro, CP-615,003 displayed quinidine-like efflux in MDR1-expressing Madin-Darby canine kidney II cells. The brain-to-serum ratio of CP-615,003 in mdr1a/1b (-/-) mice was approximately 7 times that in their wild-type counterparts, confirming that impaired CNS distribution was explained by P-gp efflux transport. In contrast, P-gp efflux did not explain the impaired CNS penetration of CP-900,725. Intracerebral microdialysis was used to characterize rat brain extracellular fluid (ECF) distribution. Interestingly, the ECF-to-serum ratio of the P-gp substrate CP-615,003 was 7-fold below the CSF-to-serum ratio, whereas this disequilibrium was not observed for CP-900,725. In a clinical study, steady-state CSF exposures were measured after administration of 100 mg of CP-615,003 b.i.d. The human CSF-to-plasma ratios of CP-615,003 and CP-900,725 were both approximately 10-fold below their ex vivo plasma unbound fractions, confirming impaired human CNS penetration. Preliminary estimates of CNS receptor occupancy from human CSF concentrations were sensitive to assumptions regarding the magnitude of the CSF-ECF gradient for CP-615,003 in humans. In summary, this case provides an example of intersite differences in CNS pharmacokinetics of a P-gp substrate and potential implications for projection of human CNS receptor occupancy of transporter substrates from CSF pharmacokinetic data when direct imaging-based approaches are not feasible.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B/genetics
- ATP Binding Cassette Transporter, Subfamily B/metabolism
- ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics
- ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
- ATP-Binding Cassette Transporters/genetics
- ATP-Binding Cassette Transporters/metabolism
- Animals
- Area Under Curve
- Biological Transport
- Brain/metabolism
- Brain Chemistry
- Cell Line
- Central Nervous System/metabolism
- Cerebrospinal Fluid/metabolism
- Dogs
- Extracellular Fluid/metabolism
- GABA-A Receptor Agonists
- Humans
- Indoles/blood
- Indoles/metabolism
- Indoles/pharmacokinetics
- Male
- Mice
- Mice, Inbred Strains
- Mice, Knockout
- Microdialysis
- Rats
- Rats, Sprague-Dawley
- Receptors, GABA-A/metabolism
- ATP-Binding Cassette Sub-Family B Member 4
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Affiliation(s)
- Karthik Venkatakrishnan
- Department of Clinical Pharmacology, Pfizer Global Research and Development, Groton, Connecticut 06340, USA.
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Ohe T, Sato M, Tanaka S, Fujino N, Hata M, Shibata Y, Kanatani A, Fukami T, Yamazaki M, Chiba M, Ishii Y. Effect of P-glycoprotein-mediated efflux on cerebrospinal fluid/plasma concentration ratio. Drug Metab Dispos 2003; 31:1251-4. [PMID: 12975334 DOI: 10.1124/dmd.31.10.1251] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The ratio of drug levels in cerebrospinal fluid (CSF) to plasma (CSF/plasma) at equilibrium has been viewed as in vivo free fraction (fp) in plasma [CSF/plasma = fp], if no active transport is involved in brain penetration. We determined the CSF/plasma level following oral administration in rats and in vitro rat plasma protein binding for 20 compounds that were synthesized in our institute and have similar physicochemical properties. However, results indicated that the CSF/plasma was not only poorly correlated with fp but remarkably lower than fp in most of the compounds tested, suggesting that certain transporters such as P-glycoprotein (P-gp) located in blood-brain barrier (BBB) may decrease the unbound drug concentration in the brain. We evaluated P-gp-mediated transport activity of the 20 compounds with P-gp (mdr1a)-transfected LLC-PK1 cells and calculated P-gp efflux index (PEI), indicating the extent of P-gp-mediated transport. A plot of the CSF/plasma versus fp/PEI showed a strong correlation (r = 0.93), and the absolute values were almost identical [CSF/plasma = fp/PEI]. These results suggest that P-gp quantitatively shifts the equilibrium of unbound drugs across the BBB. Although we cannot rule out the possibility that endogenous transporters other than P-gp on BBB and/or blood-CSF barrier may affect CSF levels of compounds, the present study indicated that fp and PEI measurements may be useful in predicting in vivo CSF/plasma fractions for central nervous system-targeting drugs.
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Affiliation(s)
- Tomoyuki Ohe
- Banyu Tsukuba Research Institute, Ibaraki, Japan.
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Agon P, Kaufman JM, Goethals P, Van Haver D, Bogaert MG. Study with positron emission tomography of the osmotic opening of the dog blood-brain barrier for quinidine and morphine. J Pharm Pharmacol 1988; 40:539-43. [PMID: 2907006 DOI: 10.1111/j.2042-7158.1988.tb05298.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A canine model was used to evaluate the possibilities offered by positron emission tomography (PET) for the study of drug distribution in the brain during altered states of the blood-brain barrier (BBB). PET was used to monitor the changes in the distribution of [11C]quinidine and [11C]morphine resulting from BBB-disruption by intracarotid infusion of a hyperosmolar mannitol solution. Injection of Evans blue dye allowing post-mortem evaluation of the degree of BBB-opening was used as a reference method. Brain radioactivity concentrations observed after i.v. injection of either [11C] quinidine or [11C]morphine were markedly increased by intracarotid mannitol infusion, whereas they were not affected by saline infusion. For both drugs a close correlation was found between the radioactivity concentrations and the degree of Evans blue staining within the brain hemispheres and within smaller regions of interest corresponding to quadrants of a hemisphere. This parallelism between the findings for radioactivity concentrations and Evans blue staining suggests that PET allows the detection of in-vivo changes in brain distribution of drugs resulting from alterations of the BBB permeability.
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Affiliation(s)
- P Agon
- Heymans Institute of Pharmacology, University of Gent, Belgium
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Ochs HR, Greenblatt DJ, Abernethy DR, Arendt RM, Gerloff J, Eichelkraut W, Hahn N. Cerebrospinal fluid uptake and peripheral distribution of centrally acting drugs: relation to lipid solubility. J Pharm Pharmacol 1985; 37:428-31. [PMID: 2862269 DOI: 10.1111/j.2042-7158.1985.tb03030.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In an anaesthetized dog model, serum kinetics and CSF entry were determined after i.v. administration of the following 8 drugs: salicylic acid (as acetylsalicylic acid), antipyrine, acetaminophen (paracetamol), lidocaine (lignocaine), trimipramine, amitriptyline, haloperidol, and imipramine. Kinetic variables were evaluated in relation to in-vitro lipophilicity, measured by the reverse-phase high-pressure liquid chromatographic (HPLC) retention index. After correction for individual values of serum binding (determined as the CSF: serum ratio at equilibrium), in-vivo volume of distribution was highly correlated with HPLC retention (r = 0.92). Conversely, the time of peak CSF concentration and the CSF entry half-life were negatively correlated with HPLC retention (r = -0.83 and -0.63, respectively). Thus lipophilicity is a physiochemical property which has an influence on the peripheral distribution of drugs as well as their rate of entry into CSF.
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Harashima H, Sugiyama Y, Sawada Y, Iga T, Hanano M. Comparison between in-vivo and in-vitro tissue-to-plasma unbound concentration ratios (Kp,f) of quinidine in rats. J Pharm Pharmacol 1984; 36:340-2. [PMID: 6145776 DOI: 10.1111/j.2042-7158.1984.tb04390.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The comparison between in-vivo and in-vitro tissue-to-plasma concentration ratio of drug unbound (Kp,f) has been made using quinidine as a model for weak basic drugs. In-vitro Kp,f-values were calculated from the binding data to tissue homogenates determined by equilibrium dialysis. In-vivo Kp,f-values were calculated from the tissue distribution data after intravenous administration of quinidine, by considering the difference in the unbound concentration between plasma and the tissues produced by the pH difference across the cell membrane. It was concluded that the extensive tissue distribution of quinidine observed in-vivo may be explained by tissue binding and the pH-difference across the cell membrane in most tissues.
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Haloperidol determination in serum and cerebrospinal fluid using gas—liquid chromatography with nitrogen—phosphorus detection: Application to pharmacokinetic studies. ACTA ACUST UNITED AC 1984. [DOI: 10.1016/s0378-4347(00)84087-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Greenblatt DJ, Matlis R, Abernethy DR, Oche HR. Improved liquid chromatographic analysis of phenytoin and salicylate using radial compression separation. JOURNAL OF CHROMATOGRAPHY 1983; 275:450-7. [PMID: 6619253 DOI: 10.1016/s0378-4347(00)84395-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Greenblatt DJ, Ochs HR, Lloyd BL. Entry of diazepam and its major matabolite into cerebrospinal fluid. Psychopharmacology (Berl) 1980; 70:89-93. [PMID: 6775342 DOI: 10.1007/bf00432376] [Citation(s) in RCA: 71] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Five dogs received a single 1.0 mg/kg dose of diazepam (DZ) IV. Concentrations of DZ and its major metabolite desmethyldiazepam (DMDZ) were simultaneously measured in plasma and cisternal cerebrospinal fluid (CSF) for up to 8 h after the dose by electron-capture gas-liquid chromatography. DZ was rapidly eliminated from plasma (half-life 0.3--1.3 h); DZ disappearance was mirrored by formation of DMDZ, which in turn was eliminated slowly, Both DZ and DMDZ rapidly penetrated CSF and concentrations in CSF declined parallel with those in plasma. Despite rapid uptake, the extent of CSF transfer of DZ and DMDZ was limited by plasma protein binding. Mean CSF:plasma concentrtion ratios for DZ (range 0.023--0.137) and DMDZ (range 0.047--0.119) were highly correlated with the unbound fraction in plasma (r = 0.95 and 0.80, respectively). Thus DZ and DMDZ concentrations in CSF, presumed to reflect concentrations at the site of action, are determined by unbound plasma concentrations. The intensity of pharmacologic action is more likely to correlate with unbound than with total plasma concentrations.
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