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Pereira WDP, Carvalheira L, Lopes JM, Aguiar PFD, Moreira RM, Oliveira ECD. Data reconciliation connected to guard bands to set specification limits related to risk assessment for radiopharmaceutical activity. Heliyon 2023; 9:e22992. [PMID: 38125475 PMCID: PMC10731080 DOI: 10.1016/j.heliyon.2023.e22992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 11/22/2023] [Accepted: 11/23/2023] [Indexed: 12/23/2023] Open
Abstract
Radiopharmaceuticals have been used to diagnose several diseases, particularly because the procedure is non-invasive. However, it is important that the correct amount of radiopharmaceutical is used to avoid inaccurate diagnostic results and suboptimal therapeutic outcomes. The amount of the radiopharmaceutical is measured when produced (by the supplier) and a second time (by the receiver), before it's use. When measured at the receiver, the result is corrected for its normal radioactivity decay. Even then, it is possible that both measurements should be considered nominal different or even statistically different when compared through various statistical tools. This research combines two innovative techniques in the field of clinical metrology. The first technique is data reconciliation, which not only enhances measurement accuracy but also reduces measurement uncertainty. The second technique involves using uncertainty information to establish specification limits for compliance assessments. In this way, our proposal aimed to minimize the risk of making incorrect decisions regarding the conformity of the concentration of radiopharmaceutical activity, that is, rejecting an item or batch that is within specification or accepting an item or batch that is outside of specification. A spreadsheet, based on these metrology fundamentals, is available to help the user with the calculations, presenting numerical and graphical results for some common radioisotopes. Reliable specification limits can be calculated and used to determine if the radiopharmaceutical is in accordance with its proposed application.
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Affiliation(s)
| | - Luciana Carvalheira
- Argonauta Reactor Service, Nuclear Engineering Institute, R. Hélio de Almeida 75, 21941-614, Rio de Janeiro, Brazil
| | - José Marques Lopes
- Earth and Environmental Physics Department, Physics Institute, Federal University of Bahia, Campus Universitário de Ondina, 40210-340, Salvador, Brazil
- Postgraduate Program in Geochemistry, Petroleum and Environment (POSPETRO), Federal University of Bahia, Av. Milton Santos s/n°, Salvador, 40170-110, Brazil
| | - Paula Fernandes de Aguiar
- Federal University of Rio de Janeiro, Chemistry Institute, Avenida Athos da Silveira Ramos 149, 21941-909, Rio de Janeiro, Brazil
| | - Rosana Medeiros Moreira
- National Institute of Technology, Av. Venezuela 82 20081-312, Rio de Janeiro, Brazil
- National Institute of Metrology, Quality and Technology (INMETRO), Av. Nossa Senhora das Graças 50, 25250-020, Duque de Caxias, Brazil
| | - Elcio Cruz de Oliveira
- Postgraduate Programme in Metrology, Pontifical Catholic University of Rio de Janeiro, R. Marquês de São Vicente 225, 22451-900, Rio de Janeiro, Brazil
- Logistics, Operational Planning and Control, Measurement and Product Inventory Management, PETROBRAS S.A., Av. Henrique Valadares 28, 20231-030, Rio de Janeiro, Brazil
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Mossel P, Arif WM, De Souza GS, Varela LG, van der Weijden CWJ, Boersma HH, Willemsen ATM, Boellaard R, Elsinga PH, Borra RJH, Dierckx RAJO, Lammertsma AA, Bartels AL, Luurtsema G. Quantification of P-glycoprotein function at the human blood-brain barrier using [ 18F]MC225 and PET. Eur J Nucl Med Mol Imaging 2023; 50:3917-3927. [PMID: 37552369 PMCID: PMC10611838 DOI: 10.1007/s00259-023-06363-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 07/24/2023] [Indexed: 08/09/2023]
Abstract
INTRODUCTION P-glycoprotein (P-gp) is one of the most studied efflux transporters at the blood-brain barrier. It plays an important role in brain homeostasis by protecting the brain from a variety of endogenous and exogeneous substances. Changes in P-gp function are associated both with the onset of neuropsychiatric diseases, including Alzheimer's disease and Parkinson's disease, and with drug-resistance, for example in treatment-resistant depression. The most widely used approach to measure P-gp function in vivo is (R)-[11C]verapamil PET. (R)-[11C]verapamil is, however, an avid P-gp substrate, which complicates the use of this tracer to measure an increase in P-gp function as its baseline uptake is already very low. [18F]MC225 was developed to measure both increases and decreases in P-gp function. AIM The aim of this study was (1) to identify the pharmacokinetic model that best describes [18F]MC225 kinetics in the human brain and (2) to determine test-retest variability. METHODS Five (2 male, 3 female) of fourteen healthy subjects (8 male, 6 female, age 67 ± 5 years) were scanned twice (injected dose 201 ± 47 MBq) with a minimum interval of 2 weeks between scans. Each scanning session consisted of a 60-min dynamic [18F]MC225 scan with continuous arterial sampling. Whole brain grey matter data were fitted to a single tissue compartment model, and to reversible and irreversible two tissue-compartment models to obtain various outcome parameters (in particular the volume of distribution (VT), Ki, and the rate constants K1 and k2). In addition, a reversible two-tissue compartment model with fixed k3/k4 was included. The preferred model was selected based on the weighted Akaike Information Criterion (AIC) score. Test-retest variability (TRTV) was determined to assess reproducibility. RESULTS Sixty minutes post-injection, the parent fraction was 63.8 ± 4.0%. The reversible two tissue compartment model corrected for plasma metabolites with an estimated blood volume (VB) showed the highest AIC weight score of 34.3 ± 17.6%. The TRVT of the VT for [18F]MC225 PET scans was 28.3 ± 20.4% for the whole brain grey matter region using this preferred model. CONCLUSION [18F]MC225 VT, derived using a reversible two-tissue compartment model, is the preferred parameter to describe P-gp function in the human BBB. This outcome parameter has an average test-retest variability of 28%. TRIAL REGISTRATION EudraCT 2020-001564-28 . Registered 25 May 2020.
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Affiliation(s)
- Pascalle Mossel
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Wejdan M Arif
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- College of Applied Medical Science, Department of Radiological Sciences, King Saud University, Riyadh, Saudi Arabia
| | - Giordana Salvi De Souza
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Lara Garcia Varela
- Molecular Imaging Biomarkers Group, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela (USC), 15706, Santiago de Compostela, Spain
- Nuclear Medicine Department and Molecular Imaging Group, Health Research Institute of Santiago de Compostela (IDIS), SERGAS, 15706, Santiago de Compostela, Spain
| | - Chris W J van der Weijden
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- Department of Radiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Hendrikus H Boersma
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Antoon T M Willemsen
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Ronald Boellaard
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- Department of Radiology and Nuclear Medicine, UMC, Location VUmc, Amsterdam, The Netherlands
| | - Philip H Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Ronald J H Borra
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Rudi A J O Dierckx
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Adriaan A Lammertsma
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Anna L Bartels
- Department of Neurology, Ommelander Ziekenhuis Groep, Scheemda, The Netherlands
| | - Gert Luurtsema
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
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3
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Dose-response assessment of cerebral P-glycoprotein inhibition in vivo with [ 18F]MC225 and PET. J Control Release 2022; 347:500-507. [PMID: 35588934 DOI: 10.1016/j.jconrel.2022.05.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 05/09/2022] [Accepted: 05/11/2022] [Indexed: 11/20/2022]
Abstract
The Blood-Brain Barrier P-glycoprotein (P-gp) function can be altered in several neurodegenerative diseases and due to the administration of different drugs which may cause alterations in drug concentrations and consequently lead to a reduced effectiveness or increased side-effects. The novel PET radiotracer [18F]MC225 is a weak P-gp substrate that may show higher sensitivity to detect small changes in P-gp function than previously developed radiotracers. This study explores the sensitivity of [18F]MC225 to measure the dose-dependent effect of P-gp inhibitor tariquidar. Twenty-three rats were intravenously injected with different doses of tariquidar ranging from 0.75 to 12 mg/kg, 30-min before the dynamic [18F]MC225-PET acquisition with arterial sampling. Tissue and blood data were fitted to a 1-Tissue-Compartment-Model to obtain influx constant K1 and distribution volume VT, which allow the estimation of P-gp function. ANOVA and post-hoc analyses of K1 values showed significant differences between controls and groups with tariquidar doses >3 mg/kg; while applying VT the analyses showed significant differences between controls and groups with tariquidar doses >6 mg/kg. Dose-response curves were fitted using different models. The four-parameter logistic sigmoidal curve provided the best fit for K1 and VT data. Half-maximal inhibitory doses (ID50) were 2.23 mg/kg (95%CI: 1.669-2.783) and 2.93 mg/kg (95%CI: 1.135-3.651), calculated with K1 or VT values respectively. According to the dose-response fit, differences in [18F]MC225-K1 values could be detected at tariquidar doses ranging from 1.37 to 3.25 mg/kg. Our findings showed that small changes in the P-gp function, caused by low doses of tariquidar, could be detected by [18F]MC225-K1 values, which confirms the high sensitivity of the radiotracer. The results suggest that [18F]MC225 may allow the quantification of moderate P-gp impairments, which may allow the detection of P-gp dysfunctions at the early stages of a disease and potential transporter-mediated drug-drug interactions.
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Ji L, Fang Y, Tang J, Liu C, Huang C, Hu Q, Li Q, Chen Z. Synthesis and biological evaluation of 18F-labelled dopamine D 3 receptor selective ligands. Bioorg Med Chem Lett 2022; 62:128630. [PMID: 35182773 DOI: 10.1016/j.bmcl.2022.128630] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 02/13/2022] [Accepted: 02/14/2022] [Indexed: 12/29/2022]
Abstract
The dopamine D3 receptor (D3R) is highly expressed in the limbic regions of the brain and closely related to a variety of neurological disorders including Parkinson's disease, schizophrenia and drug-seeking behavior. In vivo imaging of D3R with radio-labelled tracers and positron emission tomography (PET) has become a powerful technique in related disorders. In this study, we synthesized three novel aromatically 18F-labelled phenylpiperazine-like D3R selective radioactive ligands ([18F]5b, [18F]8b and [18F]11b) and developed a simple, rapid and efficient 18F-labelling method by condition optimization. Radiosynthesis of [18F]5b, [18F]8b and [18F]11b was achieved by 18F-fluorination from nitroarene precursors. Final radiochemical purities of [18F]5b, [18F]8b and [18F]11b solution were > 99% and remained good stability (> 98% for up to 6 h) in PBS and FBS. PET imaging and cellular binding studies revealed that [18F]8b had a higher D3R affinity than [18F]5b and [18F]11b. Autoradiography and biodistribution studies of the brain showed that [18F]8b had medium intensity specific accumulation in the striatum and cortex. Meanwhile, the low skeletal uptake of [18F]8b revealed a good in vivo stability with negligible defluorination. These results indicated that [18F]8b might be a potential 18F-labelled D3R PET imaging agent.
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Affiliation(s)
- Linyang Ji
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, Xuzhou 221004, China
| | - Yi Fang
- NHC Key Laboratory of Nuclear Medicine, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi 214063, China
| | - Jie Tang
- NHC Key Laboratory of Nuclear Medicine, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi 214063, China
| | - Chunyi Liu
- NHC Key Laboratory of Nuclear Medicine, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi 214063, China
| | - Caiyun Huang
- School of Pharmaceutical Science, Inner Mongolia Medical University, Hohhot 010110, China
| | - Qianyue Hu
- Department of Radiopharmaceuticals, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Qingming Li
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, Xuzhou 221004, China
| | - Zhengping Chen
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, Xuzhou 221004, China; NHC Key Laboratory of Nuclear Medicine, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi 214063, China.
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Toyohara J, Sakata M, Ishibashi K, Mossel P, Imai M, Wagatsuma K, Tago T, Imabayashi E, Colabufo NA, Luurtsema G, Ishii K. First clinical assessment of [ 18F]MC225, a novel fluorine-18 labelled PET tracer for measuring functional P-glycoprotein at the blood-brain barrier. Ann Nucl Med 2021; 35:1240-1252. [PMID: 34368924 DOI: 10.1007/s12149-021-01666-9] [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: 05/25/2021] [Accepted: 08/02/2021] [Indexed: 12/01/2022]
Abstract
OBJECTIVE 5-(1-(2-[18F]fluoroethoxy))-[3-(6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl)-propyl]-5,6,7,8-tetrahydronaphthalen ([18F]MC225) is a selective substrate for P-glycoprotein (P-gp), possessing suitable properties for measuring overexpression of P-gp in the brain. This is the first-in-human study to examine safety, radiation dosimetry and P-gp function at the blood-brain barrier (BBB) of [18F]MC225 in healthy subjects. METHODS [18F]MC225 biodistribution and dosimetry were determined in 3 healthy male subjects, using serial 2 h and intermittent 4 and 6 h whole-body PET scans acquired after [18F]MC225 injection. Dynamic [18F]MC225 brain PET (90 min) was obtained in 5 healthy male subjects. Arterial blood was sampled at various time intervals during scanning and the fraction of unchanged [18F]MC225 in plasma was determined. T1-weighted MRI was performed for anatomical coregistration. Total distribution volume (VT) was estimated using 1- and 2-tissue-compartment models (1-TCM and 2-TCM, respectively). VT was also estimated using the Logan graphical method (Logan plot) (t* = 20 min). Surrogate parameters without blood sampling (area-under the curve [AUC] of regional time-activity curves [TACs] and negative slope of calculated TACs) were compared with the VT values. RESULTS No serious adverse events occurred throughout the study period. Although biodistribution implied hepatobiliary excretion, secretion of radioactivity from liver to small intestine through the gallbladder was very slow. Total renal excreted radioactivity recovered during 6 h after injection was < 2%ID. Absorbed dose was the highest in the pancreas (mean ± SD, 203 ± 45 μGy/MBq) followed by the liver (83 ± 11 μGy/MBq). Mean effective dose with and without urination was 17 ± 1 μSv/MBq. [18F]MC225 readily entered the brain, distributing homogeneously in grey matter regions. 2-TCM provided lower Akaike information criterion scores than did 1-TCM. VT estimated by Logan plot was well correlated with that of 2-TCM (r2 > 0.9). AUCs of TACs were positively correlated with VT (2-TCM) values (r2: AUC0-60 min = 0.61, AUC0-30 min = 0.62, AUC30-60 min = 0.59, p < 0.0001). Negative slope of SUV TACs was negatively correlated with VT (2-TCM) values (r2 = 0.53, p < 0.0001). CONCLUSIONS This initial evaluation indicated that [18F]MC225 is a suitable and safe PET tracer for measuring P-gp function at the BBB.
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Affiliation(s)
- Jun Toyohara
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo, 173-0015, Japan.
| | - Muneyuki Sakata
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo, 173-0015, Japan
| | - Kenji Ishibashi
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo, 173-0015, Japan
| | - Pascalle Mossel
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Masamichi Imai
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo, 173-0015, Japan
| | - Kei Wagatsuma
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo, 173-0015, Japan.,School of Allied Health Science, Kitasato University, 1-15-1 Kitasato, Sagamihara, Kanagawa, 252-0373, Japan
| | - Tetsuro Tago
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo, 173-0015, Japan
| | - Etsuko Imabayashi
- Department of Diagnostic Radiology, Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo, 173-0015, Japan
| | - Nicola A Colabufo
- Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari, via Orabona 4, 70125, Bari, Italy
| | - Gert Luurtsema
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Kenji Ishii
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo, 173-0015, Japan
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García-Varela L, Rodríguez-Pérez M, Custodia A, Moraga-Amaro R, Colabufo NA, Aguiar P, Sobrino T, Dierckx RA, van Waarde A, Elsinga PH, Luurtsema G. In Vivo Induction of P-Glycoprotein Function can be Measured with [ 18F]MC225 and PET. Mol Pharm 2021; 18:3073-3085. [PMID: 34228458 PMCID: PMC8383301 DOI: 10.1021/acs.molpharmaceut.1c00302] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 06/24/2021] [Accepted: 06/24/2021] [Indexed: 12/12/2022]
Abstract
P-Glycoprotein (P-gp) is an efflux pump located at the blood-brain barrier (BBB) that contributes to the protection of the central nervous system by transporting neurotoxic compounds out of the brain. A decline in P-gp function has been related to the pathogenesis of neurodegenerative diseases. P-gp inducers can increase the P-gp function and are considered as potential candidates for the treatment of such disorders. The P-gp inducer MC111 increased P-gp expression and function in SW480 human colon adenocarcinoma and colo-320 cells, respectively. Our study aims to evaluate the P-gp inducing effect of MC111 in the whole brain in vivo, using the P-gp tracer [18F]MC225 and positron emission tomography (PET). Eighteen Wistar rats were treated with either vehicle solution, 4.5 mg/kg of MC111 (low-dose group), or 6 mg/kg of MC111 (high-dose group). Animals underwent a 60 min dynamic PET scan with arterial-blood sampling, 24 h after treatment with the inducer. Data were analyzed using the 1-tissue-compartment model and metabolite-corrected plasma as the input function. Model parameters such as the influx constant (K1) and volume of distribution (VT) were calculated, which reflect the in vivo P-gp function. P-gp and pregnane xenobiotic receptor (PXR) expression levels of the whole brain were assessed using western blot. The administration of MC111 decreased K1 and VT of [18F]MC225 in the whole brain and all of the selected brain regions. In the high-dose group, whole-brain K1 was decreased by 34% (K1-high-dose = 0.20 ± 0.02 vs K1-control = 0.30 ± 0.02; p < 0.001) and in the low-dose group by 7% (K1-low-dose = 0.28 ± 0.02 vs K1-control = 0.30 ± 0.02; p = 0.42) compared to controls. Whole-brain VT was decreased by 25% in the high-dose group (VT-high-dose = 5.92 ± 0.41 vs VT-control = 7.82 ± 0.38; p < 0.001) and by 6% in the low-dose group (VT-low-dose = 7.35 ± 0.38 vs VT-control = 7.82 ± 0.37; p = 0.38) compared to controls. k2 values did not vary after treatment. The treatment did not affect the metabolism of [18F]MC225. Western blot studies using the whole-brain tissue did not detect changes in the P-gp expression, however, preliminary results using isolated brain capillaries found an increasing trend up to 37% in treated rats. The decrease in K1 and VT values after treatment with the inducer indicates an increase in the P-gp functionality at the BBB of treated rats. Moreover, preliminary results using brain endothelial cells also sustained the increase in the P-gp expression. In conclusion, the results verify that MC111 induces P-gp expression and function at the BBB in rats. An increasing trend regarding the P-gp expression levels is found using western blot and an increased P-gp function is confirmed with [18F]MC225 and PET.
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Affiliation(s)
- Lara García-Varela
- Department
of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - Manuel Rodríguez-Pérez
- Clinical
Neurosciences Research Laboratory, Health
Research Institute of Santiago de Compostela (IDIS), 15706 Santiago
de Compostela, Spain
| | - Antía Custodia
- Clinical
Neurosciences Research Laboratory, Health
Research Institute of Santiago de Compostela (IDIS), 15706 Santiago
de Compostela, Spain
| | - Rodrigo Moraga-Amaro
- Department
of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - Nicola A. Colabufo
- Dipartimento
di Farmacia-Scienze del Farmaco, Università
degli Studi di Bari, I-70125 Bari, Italy
| | - Pablo Aguiar
- Department
of Nuclear Medicine and Molecular Imaging Group, Clinical University
Hospital, IDIS Health Research Institute, 15706 Santiago
de Compostela, Spain
| | - Tomás Sobrino
- Clinical
Neurosciences Research Laboratory, Health
Research Institute of Santiago de Compostela (IDIS), 15706 Santiago
de Compostela, Spain
| | - Rudi A.J.O. Dierckx
- Department
of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - Aren van Waarde
- Department
of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - Philip H. Elsinga
- Department
of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - Gert Luurtsema
- Department
of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
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7
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Garcia-Varela L, Attia K, Sembrano JC, Jacquet O, Antunes IF, Kwizera C, Visser TJ, Dierckx RAJO, Elsinga PH, Luurtsema G. A new approach to produce [ 18F]MC225 via one-step synthesis, a PET radiotracer for measuring P-gp function. EJNMMI Radiopharm Chem 2021; 6:24. [PMID: 34264435 PMCID: PMC8282851 DOI: 10.1186/s41181-021-00139-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 06/11/2021] [Indexed: 11/19/2022] Open
Abstract
Background [18F]MC225 is a radiotracer for imaging P-glycoprotein (P-gp) function at the blood-brain barrier. The P-gp function can be altered due to different factors, for instance, decreased P-gp function has been described in patients with Alzheimer’s or Parkinson’s Disease. The current applied radiosynthesis of [18F]MC225 involves 2 steps, including the distillation of the [18F] fluoroethylbromide intermediate. To develop a more robust synthetic procedure, it is of interest to produce the radiotracer via a 1-step synthesis. The present study describes a new synthetic approach to produce [18F]MC225 via direct 18F-fluorination. Moreover, we also provide the appropriate conditions for the automation of the synthesis. A mesylate precursor was synthesized via a multi-step synthetic route and used for the radiolabeling. The nucleophilic substitution of the mesylate group by [18F] Fluoride was automated in two different synthesis modules: IBA Synthera and Eckert and Ziegler PharmTracer (E&Z). Results The mesylate precursor was synthesized in 7 steps starting with 5-hydroxy-1-tetralone (commercially available) in practical yields. The stability of the precursor was improved via mesylate salt formation method. The radiolabeling was done by adding the mesylate precursor dissolved in DMF to the dried [18F]KF/K2.2.2 complex and heating at 140 °C for 30 min. Quality control by UPLC confirmed the production of [18F]MC225 with a molar activity (Am) higher than 100 GBq/micromole. The synthesis time in Synthera was 106 min and the product was obtained with a radiochemical purity higher than 95% and RCY of 6.5%, while the production in E&Z lasted 120 min and the product had a lower radiochemical purity (91%) and RCY (3.8%). Conclusions [18F]MC225 was successfully produced via a 1-step reaction. The procedure is suitable for automation using commercially available synthesis modules. The automation of the radiosynthesis in the Synthera module allows the production of the [18F]MC225 by a reliable and simple method.
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Affiliation(s)
- Lara Garcia-Varela
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Centre Groningen, Hanzeplein 1, 9713, GZ, Groningen, the Netherlands
| | - Khaled Attia
- Symeres, Kadijk 3, 9747, AT, Groningen, the Netherlands
| | | | | | - Inês F Antunes
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Centre Groningen, Hanzeplein 1, 9713, GZ, Groningen, the Netherlands
| | - Chantal Kwizera
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Centre Groningen, Hanzeplein 1, 9713, GZ, Groningen, the Netherlands
| | - Ton J Visser
- Symeres, Kadijk 3, 9747, AT, Groningen, the Netherlands
| | - Rudi A J O Dierckx
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Centre Groningen, Hanzeplein 1, 9713, GZ, Groningen, the Netherlands
| | - Philip H Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Centre Groningen, Hanzeplein 1, 9713, GZ, Groningen, the Netherlands
| | - Gert Luurtsema
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Centre Groningen, Hanzeplein 1, 9713, GZ, Groningen, the Netherlands.
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8
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Head-to-head comparison of (R)-[ 11C]verapamil and [ 18F]MC225 in non-human primates, tracers for measuring P-glycoprotein function. Eur J Nucl Med Mol Imaging 2021; 48:4307-4317. [PMID: 34117508 PMCID: PMC8566421 DOI: 10.1007/s00259-021-05411-2] [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: 03/04/2021] [Accepted: 05/11/2021] [Indexed: 11/03/2022]
Abstract
Purpose P-glycoprotein (P-gp) function is altered in several brain disorders; thus, it is of interest to monitor the P-gp function in vivo using PET. (R)-[11C]verapamil is considered the gold standard tracer to measure the P-gp function; however, it presents some drawbacks that limit its use. New P-gp tracers have been developed with improved properties, such as [18F]MC225. This study compares the characteristics of (R)-[11C]verapamil and [18F]MC225 in the same subjects. Methods Three non-human primates underwent 4 PET scans: 2 with (R)-[11C]verapamil and 2 with [18F]MC225, at baseline and after P-gp inhibition. The 30-min PET data were analyzed using 1-Tissue Compartment Model (1-TCM) and metabolite-corrected plasma as input function. Tracer kinetic parameters at baseline and after inhibition were compared. Regional differences and simplified methods to quantify the P-gp function were also assessed. Results At baseline, [18F]MC225 VT values were higher, and k2 values were lower than those of (R)-[11C]verapamil, whereas K1 values were not significantly different. After inhibition, VT values of the 2 tracers were similar; however, (R)-[11C]verapamil K1 and k2 values were higher than those of [18F]MC225. Significant regional differences between tracers were found at baseline, which disappeared after inhibition. The positive slope of the SUV-TAC was positively correlated to the K1 and VT of both tracers. Conclusion [18F]MC225 and (R)-[11C]verapamil show comparable sensitivity to measure the P-gp function in non-human primates. Moreover, this study highlights the 30-min VT as the best parameter to measure decreases in the P-gp function with both tracers. [18F]MC225 may become the first radiofluorinated tracer able to measure decreases and increases in the P-gp function due to its higher baseline VT. Supplementary Information The online version contains supplementary material available at 10.1007/s00259-021-05411-2.
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9
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Abstract
Incorporation of heterocycles into drug molecules can enhance physical properties and biological activity. A variety of heterocyclic groups is available to medicinal chemists, many of which have been reviewed in detail elsewhere. Oxadiazoles are a class of heterocycle containing one oxygen and two nitrogen atoms, available in three isomeric forms. While the 1,2,4- and 1,3,4-oxadiazoles have seen widespread application in medicinal chemistry, 1,2,5-oxadiazoles (furazans) are less common. This Review provides a summary of the application of furazan-containing molecules in medicinal chemistry and drug development programs from analysis of both patent and academic literature. Emphasis is placed on programs that reached clinical or preclinical stages of development. The examples provided herein describe the pharmacology and biological activity of furazan derivatives with comparative data provided where possible for other heterocyclic groups and pharmacophores commonly used in medicinal chemistry.
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Affiliation(s)
| | | | - Donald F Weaver
- Department of Fundamental Neurobiology, Krembil Research Institute, Toronto, Ontario M5T 0S8, Canada.,Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada.,Department of Medicine, University of Toronto, Toronto, Ontario M5S 3H2, Canada
| | - Mark A Reed
- Treventis Corporation, Toronto, Ontario M5T 0S8, Canada.,Department of Fundamental Neurobiology, Krembil Research Institute, Toronto, Ontario M5T 0S8, Canada
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10
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García-Varela L, Arif WM, Vállez García D, Kakiuchi T, Ohba H, Harada N, Tago T, Elsinga PH, Tsukada H, Colabufo NA, Dierckx RAJO, van Waarde A, Toyohara J, Boellaard R, Luurtsema G. Pharmacokinetic Modeling of [ 18F]MC225 for Quantification of the P-Glycoprotein Function at the Blood-Brain Barrier in Non-Human Primates with PET. Mol Pharm 2020; 17:3477-3486. [PMID: 32787277 PMCID: PMC7482398 DOI: 10.1021/acs.molpharmaceut.0c00514] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
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[18F]MC225 has been developed as a weak substrate of
P-glycoprotein (P-gp) aimed to measure changes in the P-gp function
at the blood–brain barrier with positron emission tomography.
This study evaluates [18F]MC225 kinetics in non-human primates
and investigates the effect of both scan duration and P-gp inhibition.
Three rhesus monkeys underwent two 91-min dynamic scans with blood
sampling at baseline and after P-gp inhibition (8 mg/kg tariquidar).
Data were analyzed using the 1-tissue compartment model (1-TCM) and
2-tissue compartment model (2-TCM) fits using metabolite-corrected
plasma as the input function and for various scan durations (10, 20,
30, 60, and 91 min). The preferred model was chosen according to the
Akaike information criterion and the standard errors (%) of the estimated
parameters. For the 91-min scan duration, the influx constant K1 increased by 40.7% and the volume of distribution
(VT) by 30.4% after P-gp inhibition, while
the efflux constant k2 did not change
significantly. Similar changes were found for all evaluated scan durations. K1 did not depend on scan duration (10 min—K1 = 0.2191 vs 91 min—K1 = 0.2258), while VT and k2 did. A scan duration of 10 min seems sufficient
to properly evaluate the P-gp function using K1 obtained with 1-TCM. For the 91-min scan, VT and K1 can be estimated
with a 2-TCM, and both parameters can be used to assess P-gp function.
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Affiliation(s)
- Lara García-Varela
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O. Box 30001, Groningen 9713 GZ, the Netherlands
| | - Wejdan M Arif
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O. Box 30001, Groningen 9713 GZ, the Netherlands.,Department of Radiological Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia
| | - David Vállez García
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O. Box 30001, Groningen 9713 GZ, the Netherlands
| | - Takeharu Kakiuchi
- Central Research Laboratory, Hamamatsu Photonics KK, 5000 Hirakuchi, Hamakita, Hamamatsu, Shizuoka 434-8601, Japan
| | - Hiroyuki Ohba
- Central Research Laboratory, Hamamatsu Photonics KK, 5000 Hirakuchi, Hamakita, Hamamatsu, Shizuoka 434-8601, Japan
| | - Norihiro Harada
- Central Research Laboratory, Hamamatsu Photonics KK, 5000 Hirakuchi, Hamakita, Hamamatsu, Shizuoka 434-8601, Japan
| | - Tetsuro Tago
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo 173-0015, Japan
| | - Philip H Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O. Box 30001, Groningen 9713 GZ, the Netherlands
| | - Hideo Tsukada
- Central Research Laboratory, Hamamatsu Photonics KK, 5000 Hirakuchi, Hamakita, Hamamatsu, Shizuoka 434-8601, Japan
| | - Nicola Antonio Colabufo
- Department of Pharmacy, University of Bari Aldo Moro, Bari 70121, Italy.,Biofordrug, Spin-off Università degli Studi di Bari "A. Moro", via Dante 99, Triggiano, Bari 70019, Italy
| | - Rudi A J O Dierckx
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O. Box 30001, Groningen 9713 GZ, the Netherlands
| | - Aren van Waarde
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O. Box 30001, Groningen 9713 GZ, the Netherlands
| | - Jun Toyohara
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo 173-0015, Japan
| | - Ronald Boellaard
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O. Box 30001, Groningen 9713 GZ, the Netherlands
| | - Gert Luurtsema
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O. Box 30001, Groningen 9713 GZ, the Netherlands
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11
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Toyohara J, Sakata M, Tago T, Colabufo NA, Luurtsema G. Automated synthesis, preclinical toxicity, and radiation dosimetry of [ 18F]MC225 for clinical use: a tracer for measuring P-glycoprotein function at the blood-brain barrier. EJNMMI Res 2020; 10:84. [PMID: 32700099 PMCID: PMC7376787 DOI: 10.1186/s13550-020-00674-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 07/14/2020] [Indexed: 12/27/2022] Open
Abstract
INTRODUCTION [18F]MC225 is a selective substrate for P-glycoprotein (P-gp) that has good metabolic stability and shows higher baseline uptake compared with other P-gp substrates such as (R)-[11C]Verapamil. Prior to clinical translation, it is necessary to perform process validation of the radiosynthesis, assessment of preclinical toxicity, and radiation dosimetry. METHODS The production of [18F]MC225 was automated on a CFN-MPS200 multipurpose synthesizer. The acute toxicity of MC225 was evaluated at a dose of 2.5 mg/kg bodyweight, which is more than 10,000-fold the postulated maximum clinical dose of [18F]MC225. The acute toxicity of [18F]MC225 injection at a 200-fold dose, to administer a postulated dose of 185 MBq of [18F]MC225, was also evaluated after the decay-out of 18F. The mutagenicity of MC225 was studied by a reverse mutation test using Salmonella typhimurium and Escherichia coli (Ames test). In vivo biodistribution and dosimetry studies of [18F]MC225 were carried out in normal mice. Human dosimetry was estimated using OLINDA software. RESULTS The mean decay-corrected yields of [18F]MC225 at end of synthesis were 13%, with > 99% radiochemical purity, > 1000 GBq/μmol molar activity, and ≤ 1.5 μg/185 MBq of total chemical contents. All process validation batches complied with the product specifications and the process was confirmed to be appropriate for the production of [18F]MC225. No acute toxicity of MC225 or [18F]MC225 injection was found. No mutagenic activity was observed for MC225. The biodistribution study demonstrated both hepatobiliary and renal excretion of radioactivity. The most critical organ was the pancreas, with (63.8 μGy/MBq) or without urination (63.9 μGy/MBq) at 360 min after injection. The estimated effective dose (μSv/MBq) with and without urination at 360 min after injection was calculated as 15.7 and 16.9, respectively. CONCLUSION [18F]MC225 shows acceptable pharmacological safety at the dose required for adequate PET imaging. The potential risk associated with [18F]MC225 PET imaging is well within acceptable dose limits.
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Affiliation(s)
- Jun Toyohara
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
| | - Muneyuki Sakata
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
| | - Tetsuro Tago
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
| | - Nicola A. Colabufo
- Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari Aldo Moro, Bari, Italy
| | - Gert Luurtsema
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen and University Medical Centre Groningen, Groningen, The Netherlands
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12
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García-Varela L, Vállez García D, Rodríguez-Pérez M, van Waarde A, Sijbesma JWA, Schildt A, Kwizera C, Aguiar P, Sobrino T, Dierckx RAJO, Elsinga PH, Luurtsema G. Test-Retest Repeatability of [ 18F]MC225-PET in Rodents: A Tracer for Imaging of P-gp Function. ACS Chem Neurosci 2020; 11:648-658. [PMID: 31961646 PMCID: PMC7034080 DOI: 10.1021/acschemneuro.9b00682] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
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In
longitudinal PET studies, animals are repeatedly anesthetized
which may affect the repeatability of PET measurements. The aim of
this study was to assess the effect of anesthesia on the P-gp function
as well as the reproducibility of [18F]MC225 PET scans.
Thus, dynamic PET scans with blood sampling were conducted in 13 Wistar
rats. Seven animals were exposed to isoflurane anesthesia 1 week before
the PET scan (“Anesthesia-exposed” PET). A second group
of six animals was used to evaluate the reproducibility of measurements
of P-gp function at the blood–brain barrier (BBB) with [18F]MC225. In this group, two PET scans were made with a 1
week interval (“Test” and “Retest” PET).
Pharmacokinetic parameters were calculated using compartmental models
and metabolite-corrected plasma as an input function. “Anesthesia-exposed”
animals showed a 28% decrease in whole-brain volume of distribution
(VT) (p < 0.001) compared
to “Test”, where the animals were not previously anesthetized.
The VT at “Retest” also
decreased (19%) compared to “Test” (p < 0.001). The k2 values in whole-brain
were significantly increased by 18% in “Anesthesia-exposed”
(p = 0.005) and by 15% in “Retest”
(p = 0.008) compared to “Test”. However,
no significant differences were found in the influx rate constant K1, which is considered as the best parameter
to measure the P-gp function. Moreover, Western Blot analysis did
not find significant differences in the P-gp expression of animals
not pre-exposed to anesthesia (“Test”) or pre-exposed
animals (“Retest”). To conclude, anesthesia may affect
the brain distribution of [18F]MC225 but it does not affect
the P-gp expression or function.
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Affiliation(s)
- Lara García-Varela
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - David Vállez García
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - Manuel Rodríguez-Pérez
- Clinical Neurosciences Research Laboratory, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela 15706, Spain
| | - Aren van Waarde
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - Jürgen W. A. Sijbesma
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - Anna Schildt
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - Chantal Kwizera
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - Pablo Aguiar
- Department of Nuclear Medicine and Molecular Imaging Group, Clinical University Hospital, IDIS Health Research Institute, Santiago de Compostela 15706, Spain
| | - Tomás Sobrino
- Clinical Neurosciences Research Laboratory, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela 15706, Spain
| | - Rudi A. J. O. Dierckx
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - Philip H. Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
| | - Gert Luurtsema
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O.
Box 30001, 9713 GZ Groningen, The Netherlands
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13
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Cortes-Salva MY, Shrestha S, Singh P, Morse CL, Jenko KJ, Montero Santamaria JA, Zoghbi SS, Innis RB, Pike VW. 2-(4-Methylsulfonylphenyl)pyrimidines as Prospective Radioligands for Imaging Cyclooxygenase-2 with PET-Synthesis, Triage, and Radiolabeling. Molecules 2018; 23:molecules23112850. [PMID: 30400142 PMCID: PMC6278313 DOI: 10.3390/molecules23112850] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 10/26/2018] [Accepted: 10/27/2018] [Indexed: 11/23/2022] Open
Abstract
Cyclooxygenase 2 (COX-2) is an inducible enzyme responsible for the conversion of arachidonic acid into the prostaglandins, PGG2 and PGH2. Expression of this enzyme increases in inflammation. Therefore, the development of probes for imaging COX-2 with positron emission tomography (PET) has gained interest because they could be useful for the study of inflammation in vivo, and for aiding anti-inflammatory drug development targeting COX-2. Nonetheless, effective PET radioligands are still lacking. We synthesized eleven COX-2 inhibitors based on a 2(4-methylsulfonylphenyl)pyrimidine core from which we selected three as prospective PET radioligands based on desirable factors, such as high inhibitory potency for COX-2, very low inhibitory potency for COX-1, moderate lipophilicity, and amenability to labeling with a positron-emitter. These inhibitors, namely 6-methoxy-2-(4-(methylsulfonyl)phenyl-N-(thiophen-2ylmethyl)pyrimidin-4-amine (17), the 6-fluoromethyl analogue (20), and the 6-(2-fluoroethoxy) analogue (27), were labeled in useful yields and with high molar activities by treating the 6-hydroxy analogue (26) with [11C]iodomethane, [18F]2-fluorobromoethane, and [d2-18F]fluorobromomethane, respectively. [11C]17, [18F]20, and [d2-18F]27 were readily purified with HPLC and formulated for intravenous injection. These methods allow these radioligands to be produced for comparative evaluation as PET radioligands for measuring COX-2 in healthy rhesus monkey and for assessing their abilities to detect inflammation.
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Affiliation(s)
- Michelle Y Cortes-Salva
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA.
| | - Stal Shrestha
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA.
| | - Prachi Singh
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA.
| | - Cheryl L Morse
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA.
| | - Kimberly J Jenko
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA.
| | - Jose A Montero Santamaria
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA.
| | - Sami S Zoghbi
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA.
| | - Robert B Innis
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA.
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA.
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14
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MC225, a Novel Probe for P-glycoprotein PET Imaging at the Blood-brain Barrier: In Vitro Cardiovascular Safety Evaluation. J Cardiovasc Pharmacol 2018; 70:405-410. [PMID: 28877068 DOI: 10.1097/fjc.0000000000000536] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The P-glycoprotein (P-gp) substrate MC225, at concentrations ≤10 nM, is a valuable radiotracer for positron emission tomography imaging of P-gp function in rats and mice. The aim of this study was to evaluate its potential toxic hazard toward the cardiovascular system through an in-depth analysis of its effects on rat aorta rings, on CaV1.2 channel current (ICa1.2) of A7r5 cells and on Langendorff-perfused rat heart. In aortic rings, MC225 relaxed phenylephrine-induced contraction in a concentration-dependent and endothelium-independent manner, with an IC50 value of about 1 μM. At concentrations ≥3 μM, it antagonized the response to cumulative concentrations of K. MC225, 1 and 10 μM, inhibited ICa1.2 by 15% and 31%, respectively, without affecting either current activation or inactivation kinetics. In Langendorff-perfused rat hearts, only 10 μM MC225 significantly decreased left ventricular pressure and increased coronary perfusion pressure while reducing heart rate and prolonging the cardiac cycle length as well as the atrioventricular conduction time (PQ interval) on the electrocardiogram. Lower concentrations of the drug were ineffective. These findings demonstrate that MC225-induced cardiovascular effects took place at concentrations that are at least 2 orders of magnitude higher than those allowing in vivo measurement of P-gp function. Therefore, MC225 represents a promising positron emission tomography tool for in vivo straightforward P-gp quantification.
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15
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Acevedo KM, Hayne DJ, McInnes LE, Noor A, Duncan C, Moujalled D, Volitakis I, Rigopoulos A, Barnham KJ, Villemagne VL, White AR, Donnelly PS. Effect of Structural Modifications to Glyoxal-bis(thiosemicarbazonato)copper(II) Complexes on Cellular Copper Uptake, Copper-Mediated ATP7A Trafficking, and P-Glycoprotein Mediated Efflux. J Med Chem 2018; 61:711-723. [DOI: 10.1021/acs.jmedchem.7b01158] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
| | | | | | | | | | | | | | - Angela Rigopoulos
- Olivia Newton-John Cancer Research Institute, Heidelberg, Victoria 3084, Australia
| | | | - Victor L. Villemagne
- Centre for PET, Department of Molecular Imaging & Therapy, Austin Health, 145 Studley Road, Heidelberg, Victoria 3084, Australia
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16
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Raaphorst RM, Luurtsema G, Schuit RC, Kooijman EJM, Elsinga PH, Lammertsma AA, Windhorst AD. Synthesis and Evaluation of New Fluorine-18 Labeled Verapamil Analogs To Investigate the Function of P-Glycoprotein in the Blood-Brain Barrier. ACS Chem Neurosci 2017; 8:1925-1936. [PMID: 28650628 PMCID: PMC5609126 DOI: 10.1021/acschemneuro.7b00086] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 06/26/2017] [Indexed: 01/19/2023] Open
Abstract
P-glycoprotein is an efflux transporter located in the blood-brain barrier. (R)-[11C]Verapamil is widely used as a PET tracer to investigate its function in patients with epilepsy, Alzheimer's disease, and other neurodegenerative diseases. Currently it is not possible to use this successful tracer in clinics without a cyclotron, because of the short half-life of carbon-11. We developed two new fluorine-18 labeled (R)-verapamil analogs, with the benefit of a longer half-life. The synthesis of (R)-N-[18F]fluoroethylverapamil ([18F]1) and (R)-O-[18F]fluoroethylnorverapamil ([18F]2) has been described. [18F]1 was obtained in reaction of (R)-norverapamil with the volatile [18F]fluoroethyltriflate acquired from bromoethyltosylate and a silver trilate column with a radiochemical yield of 2.7% ± 1.2%. [18F]2 was radiolabeled by direct fluorination of precursor 13 and required final Boc-deprotection with TFA resulting in a radiochemical yield of 17.2% ± 9.9%. Both tracers, [18F]1 and [18F]2, were administered to Wistar rats, and blood plasma and brain samples were analyzed for metabolic stability. Using [18F]1 and [18F]2, PET scans were performed in Wistar rats at baseline and after blocking with tariquidar, showing a 3.6- and 2.4-fold increase in brain uptake in the blocked rats, respectively. In addition, for both [18F]1 and [18F]2, PET scans in Mdr1a/b(-/-), Bcrp1(-/-), and WT mice were acquired, in which [18F]2 showed a more specific brain uptake in Mdr1a/b(-/-) mice and no increased signal in Bcrp1(-/-) mice. [18F]2 was selected as the best performing tracer and should be evaluated further in clinical studies.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B/deficiency
- ATP Binding Cassette Transporter, Subfamily B/genetics
- ATP Binding Cassette Transporter, Subfamily B, Member 1/antagonists & inhibitors
- ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
- ATP Binding Cassette Transporter, Subfamily G, Member 2/deficiency
- ATP Binding Cassette Transporter, Subfamily G, Member 2/genetics
- Animals
- Blood-Brain Barrier/metabolism
- Central Nervous System Agents/pharmacology
- Drug Evaluation, Preclinical
- Drug Stability
- Male
- Mice, Knockout
- Molecular Structure
- Positron-Emission Tomography
- Quinolines/pharmacology
- Radiopharmaceuticals/chemical synthesis
- Radiopharmaceuticals/pharmacokinetics
- Rats, Wistar
- Tissue Distribution
- Verapamil/chemical synthesis
- Verapamil/pharmacology
- ATP-Binding Cassette Sub-Family B Member 4
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Affiliation(s)
- Renske M. Raaphorst
- Department
of Radiology & Nuclear Medicine, VU
University Medical Center, 1081 HV Amsterdam, The Netherlands
| | - Gert Luurtsema
- Department
of Nuclear Medicine and Molecular Imaging, University Medical Center
Groningen, University of Groningen, 9712 CP Groningen, The Netherlands
| | - Robert C. Schuit
- Department
of Radiology & Nuclear Medicine, VU
University Medical Center, 1081 HV Amsterdam, The Netherlands
| | - Esther J. M. Kooijman
- Department
of Radiology & Nuclear Medicine, VU
University Medical Center, 1081 HV Amsterdam, The Netherlands
| | - Philip H. Elsinga
- Department
of Nuclear Medicine and Molecular Imaging, University Medical Center
Groningen, University of Groningen, 9712 CP Groningen, The Netherlands
| | - Adriaan A. Lammertsma
- Department
of Radiology & Nuclear Medicine, VU
University Medical Center, 1081 HV Amsterdam, The Netherlands
| | - Albert D. Windhorst
- Department
of Radiology & Nuclear Medicine, VU
University Medical Center, 1081 HV Amsterdam, The Netherlands
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Raaphorst RM, Savolainen H, Cantore M, van de Steeg E, van Waarde A, Colabufo NA, Elsinga PH, Lammertsma AA, Windhorst AD, Luurtsema G. Comparison of In Vitro Assays in Selecting Radiotracers for In Vivo P-Glycoprotein PET Imaging. Pharmaceuticals (Basel) 2017; 10:ph10030076. [PMID: 29036881 PMCID: PMC5620620 DOI: 10.3390/ph10030076] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 09/13/2017] [Accepted: 09/15/2017] [Indexed: 12/24/2022] Open
Abstract
Positron emission tomography (PET) imaging of P-glycoprotein (P-gp) in the blood-brain barrier can be important in neurological diseases where P-gp is affected, such as Alzheimer´s disease. Radiotracers used in the imaging studies are present at very small, nanomolar, concentration, whereas in vitro assays where these tracers are characterized, are usually performed at micromolar concentration, causing often discrepant in vivo and in vitro data. We had in vivo rodent PET data of [11C]verapamil, (R)-N-[18F]fluoroethylverapamil, (R)-O-[18F]fluoroethyl-norverapamil, [18F]MC225 and [18F]MC224 and we included also two new molecules [18F]MC198 and [18F]KE64 in this study. To improve the predictive value of in vitro assays, we labeled all the tracers with tritium and performed bidirectional substrate transport assay in MDCKII-MDR1 cells at three different concentrations (0.01, 1 and 50 µM) and also inhibition assay with P-gp inhibitors. As a comparison, we used non-radioactive molecules in transport assay in Caco-2 cells at a concentration of 10 µM and in calcein-AM inhibition assay in MDCKII-MDR1 cells. All the P-gp substrates were transported dose-dependently. At the highest concentration (50 µM), P-gp was saturated in a similar way as after treatment with P-gp inhibitors. Best in vivo correlation was obtained with the bidirectional transport assay at a concentration of 0.01 µM. One micromolar concentration in a transport assay or calcein-AM assay alone is not sufficient for correct in vivo prediction of substrate P-gp PET ligands.
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Affiliation(s)
- Renske M Raaphorst
- Department of Radiology & Nuclear Medicine, VU University Medical Center, De Boelelaan 1085C, 1081 HV Amsterdam, The Netherlands.
| | - Heli Savolainen
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands.
| | - Mariangela Cantore
- Dipartimento di Farmacia-Scienze del Farmaco, Università Degli Studi di Bari, via Orabona 4, 70125 Bari, Italy.
- Biofordrug slr, via Orabona 4, 70125 Bari, Italy.
| | - Evita van de Steeg
- Microbiology Systems and Biology Group, Netherlands Organisation for Applied Scientific Research (TNO), Utrechtseweg 48, 3704 HE Zeist, The Netherlands.
| | - Aren van Waarde
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands.
| | - Nicola A Colabufo
- Dipartimento di Farmacia-Scienze del Farmaco, Università Degli Studi di Bari, via Orabona 4, 70125 Bari, Italy.
- Biofordrug slr, via Orabona 4, 70125 Bari, Italy.
| | - Philip H Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands.
| | - Adriaan A Lammertsma
- Department of Radiology & Nuclear Medicine, VU University Medical Center, De Boelelaan 1085C, 1081 HV Amsterdam, The Netherlands.
| | - Albert D Windhorst
- Department of Radiology & Nuclear Medicine, VU University Medical Center, De Boelelaan 1085C, 1081 HV Amsterdam, The Netherlands.
| | - Gert Luurtsema
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands.
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18
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Langer O. Use of PET Imaging to Evaluate Transporter-Mediated Drug-Drug Interactions. J Clin Pharmacol 2017; 56 Suppl 7:S143-56. [PMID: 27385172 DOI: 10.1002/jcph.722] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 02/03/2016] [Accepted: 02/11/2016] [Indexed: 12/25/2022]
Abstract
Several membrane transporters belonging to the adenosine triphosphate-binding cassette (ABC) and solute carrier (SLC) families can transport drugs and drug metabolites and thereby exert an effect on drug absorption, distribution, and excretion, which may potentially lead to transporter-mediated drug-drug interactions (DDIs). Some transporter-mediated DDIs may lead to changes in organ distribution of drugs (eg, brain, liver, kidneys) without affecting plasma concentrations. Positron emission tomography (PET) is a noninvasive imaging method that allows studying of the distribution of radiolabeled drugs to different organs and tissues and is therefore the method of choice to quantitatively assess transporter-mediated DDIs on a tissue level. There are 2 approaches to how PET can be used in transporter-mediated DDI studies. When the drug of interest is a potential perpetrator of DDIs, it may be administered in unlabeled form to assess its influence on tissue distribution of a generic transporter-specific PET tracer (probe substrate). When the drug of interest is a potential victim of DDIs, it may be radiolabeled with carbon-11 or fluorine-18 and used in combination with a prototypical transporter inhibitor (eg, rifampicin). PET has already been used both in preclinical species and in humans to assess the effects of transporter-mediated DDIs on drug disposition in different organ systems, such as brain, liver, and kidneys, for which examples are given in the present review article. Given the growing importance of membrane transporters with respect to drug safety and efficacy, PET is expected to play an increasingly important role in future drug development.
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Affiliation(s)
- Oliver Langer
- Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.,Health and Environment Department, AIT Austrian Institute of Technology GmbH, Seibersdorf, Austria.,Medical Imaging Cluster, Medical University of Vienna, Vienna, Austria
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Saidijam M, Karimi Dermani F, Sohrabi S, Patching SG. Efflux proteins at the blood-brain barrier: review and bioinformatics analysis. Xenobiotica 2017; 48:506-532. [PMID: 28481715 DOI: 10.1080/00498254.2017.1328148] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
1. Efflux proteins at the blood-brain barrier provide a mechanism for export of waste products of normal metabolism from the brain and help to maintain brain homeostasis. They also prevent entry into the brain of a wide range of potentially harmful compounds such as drugs and xenobiotics. 2. Conversely, efflux proteins also hinder delivery of therapeutic drugs to the brain and central nervous system used to treat brain tumours and neurological disorders. For bypassing efflux proteins, a comprehensive understanding of their structures, functions and molecular mechanisms is necessary, along with new strategies and technologies for delivery of drugs across the blood-brain barrier. 3. We review efflux proteins at the blood-brain barrier, classified as either ATP-binding cassette (ABC) transporters (P-gp, BCRP, MRPs) or solute carrier (SLC) transporters (OATP1A2, OATP1A4, OATP1C1, OATP2B1, OAT3, EAATs, PMAT/hENT4 and MATE1). 4. This includes information about substrate and inhibitor specificity, structural organisation and mechanism, membrane localisation, regulation of expression and activity, effects of diseases and conditions and the principal technique used for in vivo analysis of efflux protein activity: positron emission tomography (PET). 5. We also performed analyses of evolutionary relationships, membrane topologies and amino acid compositions of the proteins, and linked these to structure and function.
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Affiliation(s)
- Massoud Saidijam
- a Department of Molecular Medicine and Genetics , Research Centre for Molecular Medicine, School of Medicine, Hamadan University of Medical Sciences , Hamadan , Iran and
| | - Fatemeh Karimi Dermani
- a Department of Molecular Medicine and Genetics , Research Centre for Molecular Medicine, School of Medicine, Hamadan University of Medical Sciences , Hamadan , Iran and
| | - Sareh Sohrabi
- a Department of Molecular Medicine and Genetics , Research Centre for Molecular Medicine, School of Medicine, Hamadan University of Medical Sciences , Hamadan , Iran and
| | - Simon G Patching
- b School of BioMedical Sciences and the Astbury Centre for Structural Molecular Biology, University of Leeds , Leeds , UK
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Savolainen H, Windhorst AD, Elsinga PH, Cantore M, Colabufo NA, Willemsen AT, Luurtsema G. Evaluation of [ 18F]MC225 as a PET radiotracer for measuring P-glycoprotein function at the blood-brain barrier in rats: Kinetics, metabolism, and selectivity. J Cereb Blood Flow Metab 2017; 37:1286-1298. [PMID: 27354093 PMCID: PMC5453451 DOI: 10.1177/0271678x16654493] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
P-glycoprotein is a protective efflux transporter at the blood-brain barrier showing altered function in many neurological disorders. The purpose of this study was to validate [18F]MC225 as a radiotracer for measuring P-glycoprotein function with positron emission tomography. Three groups of Sprague-Dawley rats were used to assess tracer uptake at baseline (group 1), after inhibition of P-glycoprotein (group 2), and after inhibition of both P-glycoprotein and breast cancer resistance protein (Bcrp, group 3). A two-tissue compartment model with a metabolite-corrected plasma input function provided the best fit to the positron emission tomography data, but parameter estimates were more reliable in a one-tissue compartment model, which was selected as the preferred model. Regional distribution volumes ( VT) in the control group ranged from 6 to 11, which is higher than for other radiotracers. [18F]MC225 showed transporter selectivity, since inhibition of P-glycoprotein caused a two to fourfold increase in the cerebral VT values, but additional inhibition of Bcrp did not cause any further increase. Metabolic stability of [18F]MC225 was moderate (at 1 h post-injection 15% of plasma radioactivity and 76% of brain radioactivity represented intact parent). Thus, [18F]MC225 may be a useful radiotracer to measure especially increases of P-glycoprotein function at the blood-brain barrier.
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Affiliation(s)
- Heli Savolainen
- 1 Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Albert D Windhorst
- 2 Department of Radiology and Nuclear Medicine, VU University Medical Center Amsterdam, Amsterdam, Netherlands
| | - Philip H Elsinga
- 1 Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Mariangela Cantore
- 3 Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari, Bari, Italy.,4 Biofordrug slr, Bari, Italy
| | - Nicola A Colabufo
- 3 Dipartimento di Farmacia-Scienze del Farmaco, Università degli Studi di Bari, Bari, Italy.,4 Biofordrug slr, Bari, Italy
| | - Antoon Tm Willemsen
- 1 Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Gert Luurtsema
- 1 Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
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21
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van der Born D, Pees A, Poot AJ, Orru RVA, Windhorst AD, Vugts DJ. Fluorine-18 labelled building blocks for PET tracer synthesis. Chem Soc Rev 2017; 46:4709-4773. [DOI: 10.1039/c6cs00492j] [Citation(s) in RCA: 113] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
This review presents a comprehensive overview of the synthesis and application of fluorine-18 labelled building blocks since 2010.
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Affiliation(s)
- Dion van der Born
- Department of Radiology & Nuclear Medicine
- VU University Medical Center
- 1081 HV Amsterdam
- The Netherlands
| | - Anna Pees
- Department of Radiology & Nuclear Medicine
- VU University Medical Center
- 1081 HV Amsterdam
- The Netherlands
| | - Alex J. Poot
- Department of Radiology & Nuclear Medicine
- VU University Medical Center
- 1081 HV Amsterdam
- The Netherlands
| | - Romano V. A. Orru
- Department of Chemistry and Pharmaceutical Sciences and Amsterdam Institute for Molecules
- Medicines & Systems (AIMMS)
- VU University Amsterdam
- Amsterdam
- The Netherlands
| | - Albert D. Windhorst
- Department of Radiology & Nuclear Medicine
- VU University Medical Center
- 1081 HV Amsterdam
- The Netherlands
| | - Danielle J. Vugts
- Department of Radiology & Nuclear Medicine
- VU University Medical Center
- 1081 HV Amsterdam
- The Netherlands
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22
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Savolainen H, Meerlo P, Elsinga PH, Windhorst AD, Dierckx RA, Colabufo NA, van Waarde A, Luurtsema G. P-glycoprotein Function in the Rodent Brain Displays a Daily Rhythm, a Quantitative In Vivo PET Study. AAPS JOURNAL 2016; 18:1524-1531. [DOI: 10.1208/s12248-016-9973-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 08/08/2016] [Indexed: 12/21/2022]
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