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Potassium channelopathies associated with epilepsy-related syndromes and directions for therapeutic intervention. Biochem Pharmacol 2023; 208:115413. [PMID: 36646291 DOI: 10.1016/j.bcp.2023.115413] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 01/06/2023] [Accepted: 01/09/2023] [Indexed: 01/15/2023]
Abstract
A number of mutations to members of several CNS potassium (K) channel families have been identified which result in rare forms of neonatal onset epilepsy, or syndromes of which one prominent characteristic is a form of epilepsy. Benign Familial Neonatal Convulsions or Seizures (BFNC or BFNS), also referred to as Self-Limited Familial Neonatal Epilepsy (SeLNE), results from mutations in 2 members of the KV7 family (KCNQ) of K channels; while generally self-resolving by about 15 weeks of age, these mutations significantly increase the probability of generalized seizure disorders in the adult, in some cases they result in more severe developmental syndromes. Epilepsy of Infancy with Migrating Focal Seizures (EIMSF), or Migrating Partial Seizures of Infancy (MMPSI), is a rare severe form of epilepsy linked primarily to gain of function mutations in a member of the sodium-dependent K channel family, KCNT1 or SLACK. Finally, KCNMA1 channelopathies, including Liang-Wang syndrome (LIWAS), are rare combinations of neurological symptoms including seizure, movement abnormalities, delayed development and intellectual disabilities, with Liang-Wang syndrome an extremely serious polymalformative syndrome with a number of neurological sequelae including epilepsy. These are caused by mutations in the pore-forming subunit of the large-conductance calcium-activated K channel (BK channel) KCNMA1. The identification of these rare but significant channelopathies has resulted in a resurgence of interest in their treatment by direct pharmacological or genetic modulation. We will briefly review the genetics, biophysics and pharmacology of these K channels, their linkage with the 3 syndromes described above, and efforts to more effectively target these syndromes.
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Deodhar M, Turgeon J, Michaud V. Contribution of CYP2D6 Functional Activity to Oxycodone Efficacy in Pain Management: Genetic Polymorphisms, Phenoconversion, and Tissue-Selective Metabolism. Pharmaceutics 2021; 13:1466. [PMID: 34575542 PMCID: PMC8468517 DOI: 10.3390/pharmaceutics13091466] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 08/26/2021] [Accepted: 09/03/2021] [Indexed: 02/01/2023] Open
Abstract
Oxycodone is a widely used opioid for the management of chronic pain. Analgesic effects observed following the administration of oxycodone are mediated mostly by agonistic effects on the μ-opioid receptor. Wide inter-subject variability observed in oxycodone efficacy could be explained by polymorphisms in the gene coding for the μ-opioid receptor (OPRM1). In humans, oxycodone is converted into several metabolites, particularly into oxymorphone, an active metabolite with potent μ-opioid receptor agonist activity. The CYP2D6 enzyme is principally responsible for the conversion of oxycodone to oxymorphone. The CYP2D6 gene is highly polymorphic with encoded protein activities, ranging from non-functioning to high-functioning enzymes. Several pharmacogenetic studies have shown the importance of CYP2D6-mediated conversion of oxycodone to oxymorphone for analgesic efficacy. Pharmacogenetic testing could optimize oxycodone therapy and help achieve adequate pain control, avoiding harmful side effects. However, the most recent Clinical Pharmacogenetics Implementation Consortium guidelines fell short of recommending pharmacogenomic testing for oxycodone treatment. In this review, we (1) analyze pharmacogenomic and drug-interaction studies to delineate the association between CYP2D6 activity and oxycodone efficacy, (2) review evidence from CYP3A4 drug-interaction studies to untangle the nature of oxycodone metabolism and its efficacy, (3) report on the current knowledge linking the efficacy of oxycodone to OPRM1 variants, and (4) discuss the potential role of CYP2D6 brain expression on the local formation of oxymorphone. In conclusion, we opine that pharmacogenetic testing, especially for CYP2D6 with considerations of phenoconversion due to concomitant drug administration, should be appraised to improve oxycodone efficacy.
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Affiliation(s)
- Malavika Deodhar
- Precision Pharmacotherapy Research and Development Institute, Tabula Rasa HealthCare, Orlando, FL 32827, USA; (M.D.); (J.T.)
| | - Jacques Turgeon
- Precision Pharmacotherapy Research and Development Institute, Tabula Rasa HealthCare, Orlando, FL 32827, USA; (M.D.); (J.T.)
- Faculty of Pharmacy, Université de Montréal, Montréal, QC H3T 1J4, Canada
| | - Veronique Michaud
- Precision Pharmacotherapy Research and Development Institute, Tabula Rasa HealthCare, Orlando, FL 32827, USA; (M.D.); (J.T.)
- Faculty of Pharmacy, Université de Montréal, Montréal, QC H3T 1J4, Canada
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Thiollier T, Wu C, Porras G, Bezard E, Li Q, Zhang J, Contamin H. Microdialysis in awake macaque monkeys for central nervous system pharmacokinetics. Animal Model Exp Med 2018; 1:314-321. [PMID: 30891581 PMCID: PMC6388052 DOI: 10.1002/ame2.12046] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 11/08/2018] [Accepted: 11/14/2018] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND The brain bioavailability of novel small molecules developed to address central nervous system disease is classically documented through ex vivo or in vivo analyses conducted in rodent models. Data acquired in rodent models are, however, not easily transferrable to human as the pharmacokinetic and pharmacodynamics profiles of the species are quite different. METHODS Using drugs selected for their differential transport across the blood-brain barrier, we here demonstrate the feasibility of brain microdialysis in normal vigil macaque monkey by measuring brain extracellular fluid bioavailability of carbamazepine, digoxin, oxycodone, and quinidine. RESULTS All drugs, but digoxin, were found in dialysate samples. Drugs that are substrate of P-glycoprotein show a difference of bioavailability or brain pharmacokinetic parameters between rodents and primates. CONCLUSION Data suggest that brain microdialysis in vigil macaque monkey, the species of choice for classic pharmacokinetic/pharmacodynamics studies could help predicting human brain bioavailability of a small molecule depending on the protein involved in the efflux transport from the brain.
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Affiliation(s)
- Thibaud Thiollier
- CynbioseMarcy l'EtoileFrance
- Université de BordeauxInstitut des Maladies NeurodégénérativesUMR 5293BordeauxFrance
- CNRSInstitut des Maladies NeurodégénérativesUMR 5293BordeauxFrance
| | - Caisheng Wu
- Institute of Materia MedicaChinese Academy of Medical SciencesBeijingPeople's Republic of China
| | | | - Erwan Bezard
- Université de BordeauxInstitut des Maladies NeurodégénérativesUMR 5293BordeauxFrance
- CNRSInstitut des Maladies NeurodégénérativesUMR 5293BordeauxFrance
- Motac NeuroscienceManchesterUK
- Institute of Laboratory Animal SciencesChina Academy of Medical SciencesBeijing CityPeople's Republic of China
| | - Qin Li
- Motac NeuroscienceManchesterUK
- Institute of Laboratory Animal SciencesChina Academy of Medical SciencesBeijing CityPeople's Republic of China
| | - Jinlan Zhang
- Institute of Materia MedicaChinese Academy of Medical SciencesBeijingPeople's Republic of China
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De Lange E, vd Berg D, Bellanti F, Voskuyl R, Syvänen S. P-glycoprotein protein expression versus functionality at the blood-brain barrier using immunohistochemistry, microdialysis and mathematical modeling. Eur J Pharm Sci 2018; 124:61-70. [DOI: 10.1016/j.ejps.2018.08.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2018] [Revised: 08/14/2018] [Accepted: 08/15/2018] [Indexed: 10/28/2022]
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Thiollier T, Wu C, Contamin H, Li Q, Zhang J, Bezard E. Permeability of blood-brain barrier in macaque model of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced Parkinson disease. Synapse 2016; 70:231-9. [PMID: 26799359 DOI: 10.1002/syn.21889] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 12/06/2015] [Accepted: 01/18/2016] [Indexed: 01/16/2023]
Abstract
Brain bioavailability of drugs developed to address central nervous system diseases is classically documented through cerebrospinal fluid collected in normal animals, i.e., through an approximation as there are fundamental differences between cerebrospinal fluid and tissue contents. The fact that disease might affect brain availability of drugs is almost never considered at this stage although several conditions are associated with blood-brain barrier damage. Building upon our expertise in Parkinson's disease translational research, the present study addressed this gap comparing plasma and cerebrospinal fluid bioavailability of l-3,4-dihydroxyphenylalanine, carbamazepine, quinidine, lovastatin, and simvastatin, in healthy and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated macaques, the gold standard model of Parkinson's disease. The drugs were selected based upon their differential transport across the blood-brain barrier. Interestingly, brain bioavailability of quinidine was decreased while others were unaffected. Pharmacokinetics and pharmacodynamics experiments of drugs addressing Parkinson's disease might thus be performed in healthy animals unless the drugs are known to interact with the organic cation transporter.
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Affiliation(s)
- Thibaud Thiollier
- Cynbiose, Marcy l'Etoile, France.,Univ. de Bordeaux, Institut des Maladies Neurodégénératives, UMR 5293, 33000, Bordeaux, France.,CNRS, Institut des Maladies Neurodégénératives, UMR 5293, 33000, Bordeaux, France
| | - Caisheng Wu
- Institute of Materia Medica, Chinese Academy of Medical Sciences, Beijing, People's Republic of China, 100050
| | | | - Qin Li
- Motac Neuroscience, Manchester, United Kingdom.,Institute of Laboratory Animal Sciences, China Academy of Medical Sciences, Beijing, People's Republic of China
| | - Jinlan Zhang
- Institute of Materia Medica, Chinese Academy of Medical Sciences, Beijing, People's Republic of China, 100050
| | - Erwan Bezard
- Univ. de Bordeaux, Institut des Maladies Neurodégénératives, UMR 5293, 33000, Bordeaux, France.,CNRS, Institut des Maladies Neurodégénératives, UMR 5293, 33000, Bordeaux, France.,Institute of Laboratory Animal Sciences, China Academy of Medical Sciences, Beijing, People's Republic of China
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de Lange ECM, Hammarlund-Udenaes M. Translational aspects of blood-brain barrier transport and central nervous system effects of drugs: From discovery to patients. Clin Pharmacol Ther 2015; 97:380-94. [DOI: 10.1002/cpt.76] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 01/06/2015] [Accepted: 01/06/2015] [Indexed: 02/06/2023]
Affiliation(s)
- ECM de Lange
- Leiden Academic Centre for Drug Research; Division of Pharmacology; Leiden University, Gorlaeus Laboratories; Leiden The Netherlands
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Vitamin D receptor activation induces P-glycoprotein and increases brain efflux of quinidine: an intracerebral microdialysis study in conscious rats. Pharm Res 2014; 32:1128-40. [PMID: 25319098 DOI: 10.1007/s11095-014-1524-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 09/12/2014] [Indexed: 01/20/2023]
Abstract
PURPOSE Since the vitamin D receptor (VDR) was found to up-regulate cerebral P-glycoprotein expression in vitro and in mice, we extend our findings to rats by assessing the effect of rat Vdr activation on brain efflux of quinidine, a P-gp substrate that is eliminated primarily by cytochrome P450 3a. METHODS We treated rats with vehicle or the active VDR ligand, 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3] (4.8 or 6.4 nmol/kg i.p. every 2nd day × 4) and examined P-gp expression and cerebral quinidine disposition via microdialysis in control and treatment studies conducted longitudinally in the same rat. RESULTS The 6.4 nmol/kg 1,25(OH)2D3 dose increased cerebral P-gp expression 1.75-fold whereas hepatic Cyp3a remained unchanged. Although there was no change in systemic clearance elicited by 1,25(OH)2D3, brain extracellular fluid quinidine concentrations were lower in treated rats. We noted that insertion of indwelling catheters increased plasma protein binding of quinidine and serial sampling decreased the blood:plasma concentration ratio, factors that alter distribution ratios in microdialysis studies. After appropriate correction, KECF/P,uu and KECF/B,uu, or ratios of quinidine unbound concentrations in brain extracellular fluid to plasma or blood at steady-state, were more than halved. CONCLUSION We demonstrate that VDR activation increases cerebral P-gp expression and delimits brain penetration of P-gp substrates.
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Gao Q, Zhang Y, Wo S, Zuo Z. Elucidation of arctigenin pharmacokinetics after intravenous and oral administrations in rats: integration of in vitro and in vivo findings via semi-mechanistic pharmacokinetic modeling. AAPS JOURNAL 2014; 16:1321-33. [PMID: 25274606 DOI: 10.1208/s12248-014-9664-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 09/02/2014] [Indexed: 11/30/2022]
Abstract
Although arctigenin (AR) has attracted substantial research interests due to its promising and diverse therapeutic effects, studies regarding its biotransformation were limited. The current study aims to provide information regarding the pharmacokinetic properties of AR via various in vitro and in vivo experiments as well as semi-mechanistic pharmacokinetic modeling. Our in vitro rat microsome incubation studies revealed that glucuronidation was the main intestinal and liver metabolic pathway of AR, which occurred with V max, K m, and Clint of 47.5 ± 3.4 nmol/min/mg, 204 ± 22 μM, and 233 ± 9 μl/min/mg with intestinal microsomes and 2.92 ± 0.07 nmol/min/mg, 22.7 ± 1.2 μM, and 129 ± 4 μl/min/mg with liver microsomes, respectively. In addition, demethylation and hydrolysis of AR occurred with liver microsomes but not with intestinal microsomes. In vitro incubation of AR and its metabolites in intestinal content demonstrated that glucuronides of AR excreted in bile could be further hydrolyzed back to the parent compound, suggesting its potential enterohepatic circulation. Furthermore, rapid formation followed by fast elimination of arctigenic acid (AA) and arctigenin-4'-O-glucuronide (AG) was observed after both intravenous (IV) and oral administrations of AR in rats. Linear pharmacokinetics was observed at three different doses for AR, AA, and AG after IV administration of AR (0.48-2.4 mg/kg, r (2) > 0.99). Finally, an integrated semi-mechanistic pharmacokinetic model using in vitro enzyme kinetic and in vivo pharmacokinetic parameters was successfully developed to describe plasma concentrations of AR, AA, and AG after both IV and oral administration of AR at all tested doses.
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Affiliation(s)
- Qiong Gao
- School of Pharmacy, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, SAR, People's Republic of China
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9
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Sjöstedt N, Kortejärvi H, Kidron H, Vellonen KS, Urtti A, Yliperttula M. Challenges of using in vitro data for modeling P-glycoprotein efflux in the blood-brain barrier. Pharm Res 2014; 31:1-19. [PMID: 23797466 DOI: 10.1007/s11095-013-1124-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 06/11/2013] [Indexed: 02/06/2023]
Abstract
The efficacy of central nervous system (CNS) drugs may be limited by their poor ability to cross the bloodbrain barrier (BBB). Transporters, such as p-glycoprotein, may affect the distribution of many drugs into the CNS in conjunction with the restricted paracellular pathway of the BBB. It is therefore important to gain information on unbound drug concentrations in the brain in drug development to ensure sufficient drug exposure from plasma at the target site in the CNS. In vitro methods are routinely used in drug development to study passive permeability and p-glycoprotein efflux of new drugs. This review discusses the challenges in the use of in vitro data as input parameters in physiologically based pharmacokinetic (PBPK) models of CNS drug disposition of p-glycoprotein substrates. Experience with quinidine demonstrates the variability in in vitro parameters of passive permeability and active pglycoprotein efflux. Further work is needed to generate parameter values that are independent of the model and assay. This is a prerequisite for reliable predictions of drug concentrations in the brain in vivo.
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Kervezee L, Hartman R, van den Berg DJ, Shimizu S, Emoto-Yamamoto Y, Meijer JH, de Lange ECM. Diurnal variation in P-glycoprotein-mediated transport and cerebrospinal fluid turnover in the brain. AAPS JOURNAL 2014; 16:1029-37. [PMID: 24917180 PMCID: PMC4147055 DOI: 10.1208/s12248-014-9625-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 05/19/2014] [Indexed: 12/27/2022]
Abstract
Nearly all bodily processes exhibit circadian rhythmicity. As a consequence, the pharmacokinetic and pharmacodynamic properties of a drug may also vary with time of day. The objective of this study was to investigate diurnal variation in processes that regulate drug concentrations in the brain, focusing on P-glycoprotein (P-gp). This efflux transporter limits the distribution of many drugs in the brain. To this end, the exposure to the P-gp substrate quinidine was determined in the plasma and brain tissue after intravenous administration in rats at six different time points over the 24-h period. Our results indicate that time of administration significantly affects the exposure to quinidine in the brain. Upon inhibition of P-gp, exposure to quinidine in brain tissue is constant over the 24-h period. To gain more insight into processes regulating brain concentrations, we used intracerebral microdialysis to determine the concentration of quinidine in brain extracellular fluid (ECF) and cerebrospinal fluid (CSF) after intravenous administration at two different time points. The data were analyzed by physiologically based pharmacokinetic modeling using NONMEM. The model shows that the variation is due to higher activity of P-gp-mediated transport from the deep brain compartment to the plasma compartment during the active period. Furthermore, the analysis reveals that CSF flux is higher in the resting period compared to the active period. In conclusion, we show that the exposure to a P-gp substrate in the brain depends on time of administration, thereby providing a new strategy for drug targeting to the brain.
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Affiliation(s)
- Laura Kervezee
- Division of Pharmacology, LACDR, Leiden University, PO Box 9502, 2300 RA, Leiden, The Netherlands
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PKPD Aspects of Brain Drug Delivery in a Translational Perspective. DRUG DELIVERY TO THE BRAIN 2014. [DOI: 10.1007/978-1-4614-9105-7_9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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12
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Disease Influence on BBB Transport in Neurodegenerative Disorders. DRUG DELIVERY TO THE BRAIN 2014. [DOI: 10.1007/978-1-4614-9105-7_22] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Chan GNY, Saldivia V, Yang Y, Pang H, de Lannoy I, Bendayan R. In vivo induction of P-glycoprotein expression at the mouse blood-brain barrier: an intracerebral microdialysis study. J Neurochem 2013; 127:342-52. [PMID: 23777437 DOI: 10.1111/jnc.12344] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 06/10/2013] [Accepted: 06/13/2013] [Indexed: 11/27/2022]
Abstract
Intracerebral microdialysis was utilized to investigate the effect of P-glycoprotein (a drug efflux transporter) induction at the mouse blood-brain barrier (BBB) on brain extracellular fluid concentrations of quinidine, an established substrate of P-glycoprotein. Induction was achieved by treating male CD-1 mice for 3 days with 5 mg/kg/day dexamethasone (DEX), a ligand of the nuclear receptor, pregnane X receptor, and a P-glycoprotein inducer. Tandem liquid chromatography mass spectrometric method was used to quantify analytes in dialysate, blood and plasma. P-glycoprotein, pregnane X receptor and Cyp3a11 (metabolizing enzyme for quinidine) protein expression in capillaries and brain homogenates was measured by immunoblot analysis. Following quinidine i.v. administration, the average ratio of unbound quinidine concentrations in brain extracellular fluid (determined from dialysate samples) to plasma at steady state (375-495 min) or Kp, uu, ECF /Plasma in the DEX-treated animals was 2.5-fold lower compared with vehicle-treated animals. In DEX-treated animals, P-glycoprotein expression in brain capillaries was 1.5-fold higher compared with vehicle-treated animals while Cyp3a11 expression in brain capillaries was not significantly different between the two groups. These data demonstrate that P-gp induction mediated by DEX at the BBB can significantly reduce quinidine brain extracellular fluid concentrations by decreasing its brain permeability and further suggest that drug-drug interactions as a result of P-gp induction at the BBB are possible. Applying microdialysis, distribution of quinidine, a P-gp substrate, in mouse brain extracellular fluid (ECF) was investigated following ligand-mediated P-glycoprotein (P-gp) induction at the blood-brain barrier (BBB). We demonstrated that a PXR agonist (dexamethasone) significantly up-regulated P-gp in brain capillaries and reduced quinidine brain ECF concentrations. Our data suggest that drug-drug interactions as a result of P-gp induction at the BBB are possible.
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Affiliation(s)
- Gary N Y Chan
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
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Syvänen S, Russmann V, Verbeek J, Eriksson J, Labots M, Zellinger C, Seeger N, Schuit R, Rongen M, van Kooij R, Windhorst AD, Lammertsma AA, de Lange EC, Voskuyl RA, Koepp M, Potschka H. [11C]quinidine and [11C]laniquidar PET imaging in a chronic rodent epilepsy model: impact of epilepsy and drug-responsiveness. Nucl Med Biol 2013; 40:764-75. [PMID: 23827307 DOI: 10.1016/j.nucmedbio.2013.05.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 04/24/2013] [Accepted: 05/23/2013] [Indexed: 10/26/2022]
Abstract
INTRODUCTION To analyse the impact of both epilepsy and pharmacological modulation of P-glycoprotein on brain uptake and kinetics of positron emission tomography (PET) radiotracers [(11)C]quinidine and [(11)C]laniquidar. METHODS Metabolism and brain kinetics of both [(11)C]quinidine and [(11)C]laniquidar were assessed in naive rats, electrode-implanted control rats, and rats with spontaneous recurrent seizures. The latter group was further classified according to their response to the antiepileptic drug phenobarbital into "responders" and "non-responders". Additional experiments were performed following pre-treatment with the P-glycoprotein modulator tariquidar. RESULTS [(11)C]quinidine was metabolized rapidly, whereas [(11)C]laniquidar was more stable. Brain concentrations of both radiotracers remained at relatively low levels at baseline conditions. Tariquidar pre-treatment resulted in significant increases of [(11)C]quinidine and [(11)C]laniquidar brain concentrations. In the epileptic subgroup "non-responders", brain uptake of [(11)C]quinidine in selected brain regions reached higher levels than in electrode-implanted control rats. However, the relative response to tariquidar did not differ between groups with full blockade of P-glycoprotein by 15 mg/kg of tariquidar. For [(11)C]laniquidar differences between epileptic and control animals were only evident at baseline conditions but not after tariquidar pretreatment. CONCLUSIONS We confirmed that both [(11)C]quinidine and [(11)C]laniquidar are P-glycoprotein substrates. At full P-gp blockade, tariquidar pre-treatment only demonstrated slight differences for [(11)C]quinidine between drug-resistant and drug-sensitive animals.
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Affiliation(s)
- Stina Syvänen
- Department of Public Health and Caring Sciences, Uppsala University, Uppsala, Sweden
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Ball K, Bouzom F, Scherrmann JM, Walther B, Declèves X. Physiologically based pharmacokinetic modelling of drug penetration across the blood-brain barrier--towards a mechanistic IVIVE-based approach. AAPS JOURNAL 2013; 15:913-32. [PMID: 23784110 DOI: 10.1208/s12248-013-9496-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 05/09/2013] [Indexed: 01/09/2023]
Abstract
Predicting the penetration of drugs across the human blood-brain barrier (BBB) is a significant challenge during their development. A variety of in vitro systems representing the BBB have been described, but the optimal use of these data in terms of extrapolation to human unbound brain concentration profiles remains to be fully exploited. Physiologically based pharmacokinetic (PBPK) modelling of drug disposition in the central nervous system (CNS) currently consists of fitting preclinical in vivo data to compartmental models in order to estimate the permeability and efflux of drugs across the BBB. The increasingly popular approach of using in vitro-in vivo extrapolation (IVIVE) to generate PBPK model input parameters could provide a more mechanistic basis for the interspecies translation of preclinical models of the CNS. However, a major hurdle exists in verifying these predictions with observed data, since human brain concentrations can't be directly measured. Therefore a combination of IVIVE-based and empirical modelling approaches based on preclinical data are currently required. In this review, we summarise the existing PBPK models of the CNS in the literature, and we evaluate the current opportunities and limitations of potential IVIVE strategies for PBPK modelling of BBB penetration.
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Affiliation(s)
- Kathryn Ball
- Centre de Pharmacocinétique et Métabolisme, Groupe de Recherche Servier, Orléans, France
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Westerhout J, Smeets J, Danhof M, de Lange ECM. The impact of P-gp functionality on non-steady state relationships between CSF and brain extracellular fluid. J Pharmacokinet Pharmacodyn 2013; 40:327-42. [PMID: 23539188 PMCID: PMC4269305 DOI: 10.1007/s10928-013-9314-4] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 03/19/2013] [Indexed: 12/05/2022]
Abstract
In the development of central nervous system (CNS)-targeted drugs, the prediction of human CNS target exposure is a big challenge. Cerebrospinal fluid (CSF) concentrations have often been suggested as a ‘good enough’ surrogate for brain extracellular fluid (brainECF, brain target site) concentrations in humans. However, brain anatomy and physiology indicates prudence. We have applied a multiple microdialysis probe approach in rats, for continuous measurement and direct comparison of quinidine kinetics in brainECF, CSF, and plasma. The data obtained indicated important differences between brainECF and CSF kinetics, with brainECF kinetics being most sensitive to P-gp inhibition. To describe the data we developed a systems-based pharmacokinetic model. Our findings indicated that: (1) brainECF- and CSF-to-unbound plasma AUC0–360 ratios were all over 100 %; (2) P-gp also restricts brain intracellular exposure; (3) a direct transport route of quinidine from plasma to brain cells exists; (4) P-gp-mediated efflux of quinidine at the blood–brain barrier seems to result of combined efflux enhancement and influx hindrance; (5) P-gp at the blood–CSF barrier either functions as an efflux transporter or is not functioning at all. It is concluded that in parallel obtained data on unbound brainECF, CSF and plasma concentrations, under dynamic conditions, is a complex but most valid approach to reveal the mechanisms underlying the relationship between brainECF and CSF concentrations. This relationship is significantly influenced by activity of P-gp. Therefore, information on functionality of P-gp is required for the prediction of human brain target site concentrations of P-gp substrates on the basis of human CSF concentrations.
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Affiliation(s)
- Joost Westerhout
- Department of Pharmacology, Leiden/Amsterdam Center for Drug Research, Einsteinweg 55, 2333 CC, Leiden, The Netherlands
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de Lange EC. The mastermind approach to CNS drug therapy: translational prediction of human brain distribution, target site kinetics, and therapeutic effects. Fluids Barriers CNS 2013; 10:12. [PMID: 23432852 PMCID: PMC3602026 DOI: 10.1186/2045-8118-10-12] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 02/01/2013] [Indexed: 01/11/2023] Open
Abstract
Despite enormous advances in CNS research, CNS disorders remain the world's leading cause of disability. This accounts for more hospitalizations and prolonged care than almost all other diseases combined, and indicates a high unmet need for good CNS drugs and drug therapies.Following dosing, not only the chemical properties of the drug and blood-brain barrier (BBB) transport, but also many other processes will ultimately determine brain target site kinetics and consequently the CNS effects. The rate and extent of all these processes are regulated dynamically, and thus condition dependent. Therefore, heterogenious conditions such as species, gender, genetic background, tissue, age, diet, disease, drug treatment etc., result in considerable inter-individual and intra-individual variation, often encountered in CNS drug therapy.For effective therapy, drugs should access the CNS "at the right place, at the right time, and at the right concentration". To improve CNS therapies and drug development, details of inter-species and inter-condition variations are needed to enable target site pharmacokinetics and associated CNS effects to be translated between species and between disease states. Specifically, such studies need to include information about unbound drug concentrations which drive the effects. To date the only technique that can obtain unbound drug concentrations in brain is microdialysis. This (minimally) invasive technique cannot be readily applied to humans, and we need to rely on translational approaches to predict human brain distribution, target site kinetics, and therapeutic effects of CNS drugs.In this review the term "Mastermind approach" is introduced, for strategic and systematic CNS drug research using advanced preclinical experimental designs and mathematical modeling. In this way, knowledge can be obtained about the contributions and variability of individual processes on the causal path between drug dosing and CNS effect in animals that can be translated to the human situation. On the basis of a few advanced preclinical microdialysis based investigations it will be shown that the "Mastermind approach" has a high potential for the prediction of human CNS drug effects.
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Affiliation(s)
- Elizabeth Cm de Lange
- Division of Pharmacology, Leiden-Academic Center for Drug Research, Leiden University, Leiden, the Netherlands.
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Microdialysis in CNS PKPD Research: Unraveling Unbound Concentrations. MICRODIALYSIS IN DRUG DEVELOPMENT 2013. [DOI: 10.1007/978-1-4614-4815-0_5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Translational Approaches for Predicting CNS Drug Effects Using Microdialysis. MICRODIALYSIS IN DRUG DEVELOPMENT 2013. [DOI: 10.1007/978-1-4614-4815-0_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Syvänen S, Labots M, Tagawa Y, Eriksson J, Windhorst AD, Lammertsma AA, de Lange EC, Voskuyl RA. Altered GABAA Receptor Density and Unaltered Blood–Brain Barrier Transport in a Kainate Model of Epilepsy: An In Vivo Study Using 11C-Flumazenil and PET. J Nucl Med 2012; 53:1974-83. [DOI: 10.2967/jnumed.112.104588] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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