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Soufsaf S, Robaey P, Nekka F. An exploratory analysis of the performance of methylphenidate regimens based on a PKPD model of dopamine and norepinephrine transporter occupancy. J Pharmacokinet Pharmacodyn 2023:10.1007/s10928-023-09854-y. [PMID: 36930337 DOI: 10.1007/s10928-023-09854-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 02/23/2023] [Indexed: 03/18/2023]
Abstract
Methylphenidate (MPH) is a psychostimulant which inhibits the uptake of dopamine and norepinephrine transporters, DAT and NET, and is mostly used to treat Attention Deficit/Hyperactivity Disorder. The current dose optimization is done through titration, a cumbersome approach for patients. To assess the therapeutic performance of MPH regimens, we introduce an in silico framework composed of (i) a population pharmacokinetic model of MPH, (ii) a pharmacodynamic (PD) model of DAT and NET occupancy, (iii) a therapeutic box delimited by time and DAT occupancy, and (iv) a performance score computation. DAT occupancy data was digitized (n = 152) and described with Emax models. NET occupancy was described with a KPD model. We used this integrative framework to simulate the performance of extended-release (18-99 mg) and tid MPH regimens (25-40 mg). Early blood samples of MPH seem to lead to higher DAT occupancy, consistent with an acute tolerance observed in clinical rating scales. An Emax model with a time-dependent tolerance was fitted to available data to assess the observed clockwise hysteresis. Peak performance is observed at 63 mg. While our analysis does not deny the existence of an acute tolerance, data precision in terms of formulation and sampling times does not allow a definite confirmation of this phenomenon. This work justifies the need for a more systematic collection of DAT and NET occupancy data to further investigate the presence of acute tolerance and assess the impact of low MPH doses on its efficacy.
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Benveniste H, Lee H, Ozturk B, Chen X, Koundal S, Vaska P, Tannenbaum A, Volkow ND. Glymphatic Cerebrospinal Fluid and Solute Transport Quantified by MRI and PET Imaging. Neuroscience 2020; 474:63-79. [PMID: 33248153 DOI: 10.1016/j.neuroscience.2020.11.014] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 11/04/2020] [Accepted: 11/07/2020] [Indexed: 12/13/2022]
Abstract
Over the past decade there has been an enormous progress in our understanding of fluid and solute transport in the central nervous system (CNS). This is due to a number of factors, including important developments in whole brain imaging technology and computational fluid dynamics analysis employed for the elucidation of glymphatic transport function in the live animal and human brain. In this paper, we review the technical aspects of dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) in combination with administration of Gd-based tracers into the cerebrospinal fluid (CSF) for tracking glymphatic solute and fluid transport in the CNS as well as lymphatic drainage. Used in conjunction with advanced computational processing methods including optimal mass transport analysis, one gains new insights into the biophysical forces governing solute transport in the CNS which leads to intriguing new research directions. Considering drainage pathways, we review the novel T1 mapping technique for quantifying glymphatic transport and cervical lymph node drainage concurrently in the same subject. We provide an overview of knowledge gleaned from DCE-MRI studies of glymphatic transport and meningeal lymphatic drainage. Finally, we introduce positron emission tomography (PET) and CSF administration of radiotracers as an alternative method to explore other pharmacokinetic aspects of CSF transport into brain parenchyma as well as efflux pathways.
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Affiliation(s)
- Helene Benveniste
- Department of Anesthesiology, Yale School of Medicine, New Haven, CT, United States; Department of Biomedical Engineering, Yale School of Medicine, New Haven, CT, United States.
| | - Hedok Lee
- Department of Anesthesiology, Yale School of Medicine, New Haven, CT, United States
| | - Burhan Ozturk
- Department of Anesthesiology, Yale School of Medicine, New Haven, CT, United States
| | - Xinan Chen
- Departments of Computer Science and Applied Mathematics & Statistics, Stony Brook University, Stony Brook, NY, United States
| | - Sunil Koundal
- Department of Anesthesiology, Yale School of Medicine, New Haven, CT, United States
| | - Paul Vaska
- Department of Radiology and Biomedical Engineering, Renaissance School of Medicine at Stony Brook University, Stony Brook, NY, United States
| | - Allen Tannenbaum
- Departments of Computer Science and Applied Mathematics & Statistics, Stony Brook University, Stony Brook, NY, United States
| | - Nora D Volkow
- Laboratory for Neuroimaging, NIAAA, Bethesda, MD, United States
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Lee J, Jeon S, Hong T, Han S, Yim DS. Simulation of PET scan timings for receptor occupancy studies of CNS drugs: a simple fixed-time design performed as well as scattered time point designs. Eur J Clin Pharmacol 2015; 71:1333-9. [PMID: 26350521 DOI: 10.1007/s00228-015-1933-9] [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: 03/04/2015] [Accepted: 08/27/2015] [Indexed: 11/29/2022]
Abstract
PURPOSE This study aimed to determine the effect of PET scan timings on the reliability of occupancy parameter estimates and to identify the scan timing design that gives the most reliable occupancy parameter estimates. METHODS We compared the performance of designs with various sets of sampling time points using the stochastic simulation and estimation method in Perl-speaks-NONMEM. Biases, relative standard errors, relative estimation errors, and root mean square errors were used to compare the performance of designs. RESULTS Unlike the results of a previous report, we found that rather complicated designs where each subject or group of subjects are allocated to different scan timings were not superior to the simple, conventional fixed-time designs regardless of whether effect compartment or receptor binding models were used. CONCLUSIONS We conclude that the conventional fixed-time designs that have been used so far may give robust PD parameter estimates for occupancy data obtained from human PET studies of CNS drugs.
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Affiliation(s)
- Jongtae Lee
- Department of Clinical Pharmacology and Therapeutics, Seoul St. Mary's Hospital, Pharmacometrics Institute for Practical Education and Training (PIPET), College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul, 06591, Korea
| | - Sangil Jeon
- Clinical Trial Center, International St. Mary's Hospital, Catholic Kwandong University, Incheon, Korea
| | - Taegon Hong
- Department of Clinical Pharmacology and Therapeutics, Seoul St. Mary's Hospital, Pharmacometrics Institute for Practical Education and Training (PIPET), College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul, 06591, Korea
| | - Seunghoon Han
- Department of Clinical Pharmacology and Therapeutics, Seoul St. Mary's Hospital, Pharmacometrics Institute for Practical Education and Training (PIPET), College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul, 06591, Korea
| | - Dong-Seok Yim
- Department of Clinical Pharmacology and Therapeutics, Seoul St. Mary's Hospital, Pharmacometrics Institute for Practical Education and Training (PIPET), College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul, 06591, Korea.
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Saihkay HNS, Rickards KJ, Page CP, Ballinger JR. Validating 123I-metaiodobenzylguanidine as a platelet marker for non-invasive imaging in rabbits. J Pharmacol Toxicol Methods 2010; 63:69-78. [PMID: 20646985 DOI: 10.1016/j.vascn.2010.05.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 04/20/2010] [Accepted: 05/20/2010] [Indexed: 10/19/2022]
Abstract
INTRODUCTION Recent in vitro studies in our laboratory have demonstrated that platelets are necessary for leukocyte recruitment and airway remodelling in models of allergic airway inflammation, and also migrate to lung tissues in response to anti-IgE or relevant allergens in allergic asthma. Non-invasive imaging of platelet migration in vivo would provide a further insight into the roles of platelets in inflammatory diseases such as asthma, and metaiodobenzylguanidine (MIBG) was considered as a suitable platelet marker. METHODS The kinetics of MIBG uptake into rabbit platelets, the effect of MIBG on platelet function and the effect of platelet activation on MIBG uptake and retention were investigated. MIBG-labelled platelets were administered intravenously into rabbits and the time course of radioactivity in the lung and blood was monitored as a function of stimulation. RESULTS Following a 4h incubation of MIBG in rabbit PRP, a near maximal MIBG uptake (52.4 ± 20.2%) in platelets occurred. This time point was chosen for subsequent in vitro studies. In vitro platelet function studies showed that MIBG has no effect on ADP or PAF-induced platelet aggregation, PAF-induced thromboxane production or fMLP-induced platelet chemotaxis. However, serotonin showed a significant effect on MIBG uptake and retention, but only at high concentrations. Stimulation of rabbit platelets with ADP and PAF caused a significant release of stored MIBG in vitro. Following i.v. administration of MIBG labelled platelets, the response to i.v. ADP and PAF stimulation was small but significant. DISCUSSION The release of MIBG from platelets in vivo, particularly following stimulation, leads to high background levels. Therefore, MIBG may have limited utility as a label for imaging platelets in vivo using PET. However, it may be a useful marker in detecting pathological conditions where platelet migration is involved.
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Affiliation(s)
- Hom N S Saihkay
- The Sackler Institute of Pulmonary Pharmacology, Waterloo Campus, King's College London, London SE1 9NH, UK.
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Tashiro M, Sakurada Y, Iwabuchi K, Mochizuki H, Kato M, Aoki M, Funaki Y, Itoh M, Iwata R, Wong DF, Yanai K. Central effects of fexofenadine and cetirizine: measurement of psychomotor performance, subjective sleepiness, and brain histamine H1-receptor occupancy using 11C-doxepin positron emission tomography. J Clin Pharmacol 2005; 44:890-900. [PMID: 15286093 DOI: 10.1177/0091270004267590] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Histamine H1-receptor (H1R) antagonists, or antihistamines, often induce sedative side effects when used for the treatment of allergic disorders. This study compared the sedative profiles of the second-generation antihistamines, fexofenadine and cetirizine, using 3 different criteria: subjective sleepiness evaluated by the Stanford Sleepiness Scale, objective psychomotor tests (simple and choice reaction time tests and visual discrimination tests at 4 different exposure durations), and measurement of histamine H1-receptor occupancy (H1RO) in the brain. Subjective sleepiness and psychomotor performance were measured in 20 healthy Japanese volunteers at baseline and 90 min after administration of fexofenadine 120 mg or cetirizine 20 mg in a double-blind, placebo-controlled crossover study. Hydroxyzine 30 mg was included as a positive control. H1RO was measured using positron emission tomography (PET) with (11)C-doxepin in 12 of the 20 subjects, and a further 11 volunteers were recruited to act as controls. In psychomotor tests, fexofenadine was not significantly different from placebo and significantly less impairing than cetirizine on some tasks, as well as significantly less impairing than hydroxyzine on all tasks. For subjective sleepiness, fexofenadine was not significantly different from placebo, whereas cetirizine showed a trend toward increased sleepiness compared with fexofenadine and placebo. H1RO was negligible with fexofenadine (-0.1%) but moderately high with cetirizine (26.0%). In conclusion, fexofenadine 120 mg is distinguishable from cetirizine 20 mg, as assessed by H1RO and psychomotor testing.
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Affiliation(s)
- Manabu Tashiro
- Department of Pharmacology, Tohoku University School of Medicine, 2-1 Seiryo-cho, Aoba-ku, Sendai, Miyagi 980-8575, Japan
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Melis M, Spiga S, Diana M. The dopamine hypothesis of drug addiction: hypodopaminergic state. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2005; 63:101-54. [PMID: 15797467 DOI: 10.1016/s0074-7742(05)63005-x] [Citation(s) in RCA: 182] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Miriam Melis
- B.B. Brodie Department of Neuroscience, University of Cagliari, 09042 Monserrato, Italy
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Affiliation(s)
- Markus Rudin
- Novartis Institute for Biomedical Research, CH-4002 Basel, Switzerland
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Gulyás B, Halldin C, Sandell J, Karlsson P, Sóvágó J, Kárpáti E, Kiss B, Vas A, Cselényi Z, Farde L. PET studies on the brain uptake and regional distribution of [11C]vinpocetine in human subjects. Acta Neurol Scand 2002; 106:325-32. [PMID: 12460136 DOI: 10.1034/j.1600-0404.2002.01302.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVES Vinpocetine is a compound widely used in the prevention and treatment of cerebrovascular diseases. It is still not clear whether the drug has a direct and specific effect on neurotransmission or its effects are due to extracerebral actions, such as changes in cerebral blood flow. The main objective of the present investigation was to determine the global uptake and regional distribution of radiolabelled vinpocetine in the human brain in order to explore whether it may have direct central nervous system effects. MATERIAL AND METHODS Three healthy subjects were examined with positron emission tomography and [11C]vinpocetine. The regional uptake was determined in anatomically defined volumes-of-interest. The fractions of [11C]vinpocetine and labelled metabolites in plasma were determined using high pressure liquid chromatography. RESULTS The uptake of [11C]vinpocetine in brain was rapid and 3.7% (mean; n = 4) of the total radioactivity injected was in brain 2 min after radioligand administration. The uptake was heterogeneously distributed among brain regions. When compared with the cerebellum, an a priori reference region, the highest regional uptake was in the thalamus, upper brain stem, striatum and cortex. Following an initial peak, the total concentration of radioactivity in blood was relatively stable with time, whereas the concentration of the unchanged compound decreased with time in an exponential manner. CONCLUSION Vinpocetine, administered intravenously in humans, readily passes the blood-brain barrier and enters the brain. Its regional uptake and distribution in the brain is heterogeneous, indicating binding to specific sites. The brain regions showing increased uptake in the human brain correspond to those in which vinpocetine has been shown to induce elevated metabolism and blood flow. These observations support the hypothesis that vinpocetine has direct neuronal actions in the human brain.
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Affiliation(s)
- B Gulyás
- Department of Clinical Neuroscience, Psychiatry Section, Karolinska Institute, Stockholm, Sweden.
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Peñuelas Sánchez I. [PET radiopharmaceuticals]. REVISTA ESPANOLA DE MEDICINA NUCLEAR 2001; 20:477-98; quiz 499-501. [PMID: 11578585 DOI: 10.1016/s0212-6982(01)71997-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- I Peñuelas Sánchez
- Unidad de Radiofarmacia, Servicio de Medicina Nuclear, Clínica Universitaria de Navarra, Spain.
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Affiliation(s)
- R Frank
- Sanofi Research Division, Malvern, PA, USA
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