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Soyer A, Leterrier S, Breuil L, Goislard M, Leroy C, Saba W, Thibault K, Bo GD, Bottlaender M, Caillé F, Goutal S, Tournier N. Validation of a pharmacological imaging challenge using 11C-buprenorphine and 18F-2-fluoro-2-deoxy-D-glucose positron emission tomography to study the effects of buprenorphine to the rat brain. Front Neurosci 2023; 17:1181786. [PMID: 37234261 PMCID: PMC10205997 DOI: 10.3389/fnins.2023.1181786] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 04/17/2023] [Indexed: 05/27/2023] Open
Abstract
Aim Buprenorphine mainly acts as an agonist of mu-opioid receptors (mu-OR). High dose buprenorphine does not cause respiratory depression and can be safely administered to elicit typical opioid effects and explore pharmacodynamics. Acute buprenorphine, associated with functional and quantitative neuroimaging, may therefore provide a fully translational pharmacological challenge to explore the variability of response to opioids in vivo. We hypothesized that the CNS effects of acute buprenorphine could be monitored through changes in regional brain glucose metabolism, assessed using 18F-FDG microPET in rats. Materials and methods First, level of receptor occupancy associated with a single dose of buprenorphine (0.1 mg/kg, s.c) was investigated through blocking experiments using 11C-buprenorphine PET imaging. Behavioral study using the elevated plus-maze test (EPM) was performed to assess the impact of the selected dose on anxiety and also locomotor activity. Then, brain PET imaging using 18F-FDG was performed 30 min after injection of unlabeled buprenorphine (0.1 mg/kg, s.c) vs. saline. Two different 18F-FDG PET acquisition paradigms were compared: (i) 18F-FDG injected i.v. under anesthesia and (ii) 18F-FDG injected i.p. in awake animals to limit the impact of anesthesia. Results The selected dose of buprenorphine fully blocked the binding of 11C-buprenorphine in brain regions, suggesting complete receptor occupancy. This dose had no significant impact on behavioral tests used, regardless of the anesthetized/awake handling paradigm. In anesthetized rats, injection of unlabeled buprenorphine decreased the brain uptake of 18F-FDG in most brain regions except in the cerebellum which could be used as a normalization region. Buprenorphine treatment significantly decreased the normalized brain uptake of 18F-FDG in the thalamus, striatum and midbrain (p < 0.05), where binding of 11C-buprenorphine was the highest. The awake paradigm did not improve sensitivity and impact of buprenorphine on brain glucose metabolism could not be reliably estimated. Conclusion Buprenorphine (0.1 mg/kg, s.c) combined with 18F-FDG brain PET in isoflurane anesthetized rats provides a simple pharmacological imaging challenge to investigate the CNS effects of full receptor occupancy by this partial mu-OR agonist. Sensitivity of the method was not improved in awake animals. This strategy may be useful to investigate de desensitization of mu-OR associated with opioid tolerance in vivo.
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Affiliation(s)
- Amélie Soyer
- Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), CEA, CNRS, Inserm, Service Hospitalier Frédéric Joliot, Université Paris-Saclay, Orsay, France
| | - Sarah Leterrier
- Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), CEA, CNRS, Inserm, Service Hospitalier Frédéric Joliot, Université Paris-Saclay, Orsay, France
| | - Louise Breuil
- Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), CEA, CNRS, Inserm, Service Hospitalier Frédéric Joliot, Université Paris-Saclay, Orsay, France
| | - Maud Goislard
- Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), CEA, CNRS, Inserm, Service Hospitalier Frédéric Joliot, Université Paris-Saclay, Orsay, France
| | - Claire Leroy
- Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), CEA, CNRS, Inserm, Service Hospitalier Frédéric Joliot, Université Paris-Saclay, Orsay, France
| | - Wadad Saba
- Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), CEA, CNRS, Inserm, Service Hospitalier Frédéric Joliot, Université Paris-Saclay, Orsay, France
| | - Karine Thibault
- Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), CEA, CNRS, Inserm, Service Hospitalier Frédéric Joliot, Université Paris-Saclay, Orsay, France
- Department of Toxicology and Chemical Risks, Armed Forces Biomedical Research Institute, Bretigny sur Orge, France
| | - Gregory Dal Bo
- Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), CEA, CNRS, Inserm, Service Hospitalier Frédéric Joliot, Université Paris-Saclay, Orsay, France
- Department of Toxicology and Chemical Risks, Armed Forces Biomedical Research Institute, Bretigny sur Orge, France
| | - Michel Bottlaender
- Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), CEA, CNRS, Inserm, Service Hospitalier Frédéric Joliot, Université Paris-Saclay, Orsay, France
| | - Fabien Caillé
- Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), CEA, CNRS, Inserm, Service Hospitalier Frédéric Joliot, Université Paris-Saclay, Orsay, France
| | - Sébastien Goutal
- Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), CEA, CNRS, Inserm, Service Hospitalier Frédéric Joliot, Université Paris-Saclay, Orsay, France
| | - Nicolas Tournier
- Laboratoire d’Imagerie Biomédicale Multimodale (BioMaps), CEA, CNRS, Inserm, Service Hospitalier Frédéric Joliot, Université Paris-Saclay, Orsay, France
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Hakomäki H, Eskola S, Kokki H, Lehtonen M, Räsänen J, Laaksonen S, Voipio HM, Ranta VP, Kokki M. Central Nervous System Distribution of Buprenorphine in Pregnant Sheep, Fetuses and Newborn Lambs After Continuous Transdermal and Single Subcutaneous Extended-Release Dosing. Eur J Pharm Sci 2022; 178:106283. [PMID: 36029997 DOI: 10.1016/j.ejps.2022.106283] [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: 05/24/2022] [Revised: 08/22/2022] [Accepted: 08/23/2022] [Indexed: 11/25/2022]
Abstract
Buprenorphine is used during pregnancy for the treatment of opioid use disorder. Limited data exist on the central nervous system (CNS) permeation and distribution, and on the fetal exposure to buprenorphine. The aim of our study was to determine the extent of buprenorphine distribution to CNS in the pregnant sheep, and their fetus at steady-state, and their newborn lambs postdelivery, using three different dosing regimens. Twenty-eight pregnant ewes in late gestation received buprenorphine via 7-day transdermal patch releasing buprenorphine 20 µg/h (n=9) or 40 µg/h (n=11), or an extended-release 8 mg/week subcutaneous injection (n=8). Plasma, cerebrospinal fluid, and CNS tissue samples were collected at steady-state from ewes and fetuses, and from lambs 0.33 - 45 hours after delivery. High accumulation of buprenorphine was observed in all CNS tissues. The median CNS/plasma concentration -ratios of buprenorphine in different CNS areas ranged between 13 and 50 in the ewes, and between 26 and 198 in the fetuses. In the ewes the CNS/plasma -ratios were similar after the three dosing regimens, but higher in the fetuses in the 40 µg/h dosing group, medians 65 - 122, than in the 20 µg/h group, medians 26 - 54. The subcutaneous injection (theoretical release rate 47.6 µg/h) produced higher concentrations than observed after 40 µg/h transdermal patch dosing. The median fetal/maternal concentration -ratios in different dosing groups ranged between 0.21 and 0.54 in plasma, and between 0.38 and 1.3 in CNS tissues, respectively, with the highest ratios observed in the spinal cord. Buprenorphine concentrations in the cerebrospinal fluid were 8 - 13 % of the concurrent plasma concentration in the ewes and 28 % in the fetuses. Buprenorphine was quantifiable in the newborn lambs' plasma and CNS tissues two days postdelivery. Norbuprenorphine was analyzed from all plasma, cerebrospinal fluid, and CNS tissue samples but was nondetectable or below the LLOQ in most. The current study demonstrates that buprenorphine accumulates into CNS tissues at much higher concentrations than in plasma in pregnant sheep, fetuses, and their newborn lambs even 45 hours after delivery.
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Key Words
- BUP, Buprenorphine
- CL, Plasma clearance
- CNS, Central nervous system
- CSF, Cerebrospinal fluid
- F/M -ratio, Fetal to maternal concentration ratio
- HPLC, , High-performance liquid chromatography
- L/M -ratio, Lamb to maternal concentration ratio
- LC/MS/MS, Liquid chromatography - tandem mass spectrometry
- LLOQ, Lower limit of quantification
- NBUP, Norbuprenorphine
- brain
- buprenorphine
- pharmacokinetics, pregnancy
- sheep
- tissue
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Affiliation(s)
| | - Sophia Eskola
- School of Pharmacy, University of Eastern Finland, Kuopio, Finland
| | - Hannu Kokki
- School of Medicine, University of Eastern Finland, Kuopio, Finland
| | - Marko Lehtonen
- School of Pharmacy, University of Eastern Finland, Kuopio, Finland
| | - Juha Räsänen
- Fetal Medicine Center, Department of Obstetrics and Gynecology, Helsinki University Hospital and University of Helsinki, Helsinki, Finland
| | - Sakari Laaksonen
- Department of Comparative Medicine, Oulu Laboratory Animal Centre, Oulu University Hospital and University of Oulu, Oulu, Finland
| | - Hanna-Marja Voipio
- Department of Comparative Medicine, Oulu Laboratory Animal Centre, Oulu University Hospital and University of Oulu, Oulu, Finland
| | - Veli-Pekka Ranta
- School of Pharmacy, University of Eastern Finland, Kuopio, Finland
| | - Merja Kokki
- Department of Anesthesiology and Intensive Care, Kuopio University Hospital, Kuopio, Finland
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Diels–Alder Adducts of Morphinan-6,8-Dienes and Their Transformations. Molecules 2022; 27:molecules27092863. [PMID: 35566212 PMCID: PMC9102320 DOI: 10.3390/molecules27092863] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 04/19/2022] [Accepted: 04/20/2022] [Indexed: 02/04/2023] Open
Abstract
6,14-ethenomorphinans are semisynthetic opiate derivatives containing an ethylene bridge between positions 6 and 14 in ring-C of the morphine skeleton that imparts a rigid molecular structure. These compounds represent an important family of opioid receptor ligands in which the 6,14-etheno bridged structural motif originates from a [4 + 2] cycloaddition of morphinan-6,8-dienes with dienophiles. Certain 6,14-ethenomorphinans having extremely high affinity for opioid receptors are often non-selective for opioid receptor subtypes, but this view is now undergoing some revision. The agonist 20R-etorphine and 20R-dihydroetorphine are several thousand times more potent analgesics than morphine, whereas diprenorphine is a high-affinity non-selective antagonist. The partial agonist buprenorphine is used as an analgesic in the management of post-operative pain or in substitution therapy for opiate addiction, sometimes in combination with the non-selective antagonist naloxone. In the context of the current opioid crisis, we communicated a summary of several decades of work toward generating opioid analgesics with lesser side effects or abuse potential. Our summary placed a focus on Diels–Alder reactions of morphinan-6,8-dienes and subsequent transformations of the cycloadducts. We also summarized the pharmacological aspects of radiolabeled 6,14-ethenomorphinans used in molecular imaging of opioid receptors.
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Bourasset F, Auvity S, Thorne RG, Scherrmann JM. Brain Distribution of Drugs: Brain Morphology, Delivery Routes, and Species Differences. Handb Exp Pharmacol 2021; 273:97-120. [PMID: 33474672 DOI: 10.1007/164_2020_402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Neuropharmacokinetics considers cerebral drug distribution as a critical process for central nervous system drug action as well as for drug penetration through the CNS barriers. Brain distribution of small molecules obeys classical rules of drug partition, permeability, binding to fluid proteins or tissue components, and tissue perfusion. The biodistribution of all drugs, including both small molecules and biologics, may also be influenced by specific brain properties related to brain anatomy and physiological barriers, fluid dynamics, and cellular and biochemical composition, each of which can exhibit significant interspecies differences. All of these properties contribute to select optimal dosing paradigms and routes of drug delivery to reach brain targets for classical small molecule drugs as well as for biologics. The importance of these properties for brain delivery and exposure also highlights the need for efficient new analytical technologies to more comprehensively investigate drug distribution in the CNS, a complex multi-compartmentalized organ system.
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Affiliation(s)
- Fanchon Bourasset
- Faculty of Pharmacy, University of Paris, Paris, France.,INSERM UMR-S1144, Paris, France
| | - Sylvain Auvity
- Faculty of Pharmacy, University of Paris, Paris, France.,INSERM UMR-S1144, Paris, France
| | - Robert G Thorne
- Denali Therapeutics, Inc., South San Francisco, CA, USA. .,Department of Pharmaceutics, University of Minnesota, Minneapolis, MN, USA.
| | - Jean-Michel Scherrmann
- Faculty of Pharmacy, University of Paris, Paris, France. .,INSERM UMR-S1144, Paris, France.
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Auvity S, Breuil L, Goislard M, Bottlaender M, Kuhnast B, Tournier N, Caillé F. An original radio-biomimetic approach to synthesize radiometabolites for PET imaging. Nucl Med Biol 2020; 90-91:10-14. [PMID: 32898790 DOI: 10.1016/j.nucmedbio.2020.08.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 07/27/2020] [Accepted: 08/13/2020] [Indexed: 02/05/2023]
Abstract
To fully exploit the potential of positron emission tomography (PET) imaging to assess drug distribution and pharmacokinetics in the central nervous system, the contribution of radiometabolites to the PET signal has to be determined for correct interpretation of data. However, radiosynthesis and extensive study of radiometabolites are rarely investigated and very challenging for complex drugs. Therefore, an original radio-biomimetic (RBM) approach was developed to rapidly synthesize radiometabolites and non-invasively investigate their kinetics with PET imaging. This method enabled the challenging radiosynthesis of [11C]nor-buprenorphine ([11C]nor-BUP), the main metabolite of buprenorphine (BUP) which has been identified as a substrate of the P-glycoprotein (P-gp) transport function at the blood-brain barrier (BBB). Biomimetic conditions using cytochromes P450 3A4 to convert BUP into nor-BUP were optimized taking into account the short half-life of carbon-11 (t1/2 = 20.4 min). Those conditions afforded 32% of conversion within 20 min and were applied to the biomimetic radiosynthesis of [11C]nor-BUP from [11C]BUP. Automated radiosynthesis of [11C]BUP according to a procedure described in the literature followed by optimized RBM conditions afforded [11C]nor-BUP in 1.5% decay-corrected radiochemical yield within 90 min and 90 ± 15 GBq/μmol molar activity. HPLC quality control showed chemical and radiochemical purities above 98%. To demonstrate the applicability of the RBM approach to preclinical studies, brain PET images in rats showed a drastic lower uptake of [11C]nor-BUP (0.067 ± 0.023%ID/cm-3) compared to [11C]BUP (0.436 ± 0.054%ID/cm-3). P-gp inhibition using Tariquidar increased the brain uptake of [11C]nor-BUP (0.557 ± 0.077%ID/cm-3).
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Affiliation(s)
- Sylvain Auvity
- Université Paris-Saclay, Inserm, CNRS, CEA, Laboratoire d'Imagerie Biomédicale Multimodale Paris-Saclay, 91401 Orsay, France; Assistance Publique-Hôpitaux de Paris, Hôpital Necker - Enfants malades, Inserm, UMR-S 1144, Université de Paris, Optimisation thérapeutique en neuropsychopharmacologie, Paris, France
| | - Louise Breuil
- Université Paris-Saclay, Inserm, CNRS, CEA, Laboratoire d'Imagerie Biomédicale Multimodale Paris-Saclay, 91401 Orsay, France
| | - Maud Goislard
- Université Paris-Saclay, Inserm, CNRS, CEA, Laboratoire d'Imagerie Biomédicale Multimodale Paris-Saclay, 91401 Orsay, France
| | - Michel Bottlaender
- Université Paris-Saclay, Inserm, CNRS, CEA, Laboratoire d'Imagerie Biomédicale Multimodale Paris-Saclay, 91401 Orsay, France
| | - Bertrand Kuhnast
- Université Paris-Saclay, Inserm, CNRS, CEA, Laboratoire d'Imagerie Biomédicale Multimodale Paris-Saclay, 91401 Orsay, France
| | - Nicolas Tournier
- Université Paris-Saclay, Inserm, CNRS, CEA, Laboratoire d'Imagerie Biomédicale Multimodale Paris-Saclay, 91401 Orsay, France
| | - Fabien Caillé
- Université Paris-Saclay, Inserm, CNRS, CEA, Laboratoire d'Imagerie Biomédicale Multimodale Paris-Saclay, 91401 Orsay, France.
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van Hoogdalem MW, McPhail BT, Hahn D, Wexelblatt SL, Akinbi HT, Vinks AA, Mizuno T. Pharmacotherapy of neonatal opioid withdrawal syndrome: a review of pharmacokinetics and pharmacodynamics. Expert Opin Drug Metab Toxicol 2020; 17:87-103. [PMID: 33049155 DOI: 10.1080/17425255.2021.1837112] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
INTRODUCTION Neonatal opioid withdrawal syndrome (NOWS) often arises in infants born to mothers who used opioids during pregnancy. Morphine, methadone, and buprenorphine are the most common first-line treatments, whereas clonidine and phenobarbital are generally reserved for adjunctive therapy. These drugs exhibit substantial pharmacokinetic (PK) and pharmacodynamic (PD) variability. Current pharmacological treatments for NOWS are based on institutional protocols and largely rely on empirical treatment of patient symptoms. AREAS COVERED This article reviews the PK/PD of NOWS pharmacotherapies with a focus on the implication of physiological development and maturation. Body size-standardized clearance is consistently low in neonates, except for methadone. This can be ascribed to underdeveloped metabolic and elimination pathways. The effects of pharmacogenetics have been clarified especially for morphine. The PK/PD relationship of medications used in the treatment of NOWS is generally understudied. EXPERT OPINION Providing an appropriate opioid dose in neonates is challenging. Advancements in quantitative pharmacology and PK/PD modeling approaches facilitate identification of key factors driving PK/PD variability and characterization of exposure-response relationships. PK/PD model-informed simulations have been widely employed to define age-appropriate pediatric dosing regimens. The model-informed approach holds promise to aid more rational use of medications in the treatment of NOWS.
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Affiliation(s)
- Matthijs W van Hoogdalem
- Division of Clinical Pharmacology, Cincinnati Children's Hospital Medical Center , Cincinnati, OH, USA.,James L. Winkle College of Pharmacy, University of Cincinnati , Cincinnati, OH, USA
| | - Brooks T McPhail
- Division of Clinical Pharmacology, Cincinnati Children's Hospital Medical Center , Cincinnati, OH, USA.,School of Medicine Greenville, University of South Carolina , Greenville, SC, USA
| | - David Hahn
- Division of Clinical Pharmacology, Cincinnati Children's Hospital Medical Center , Cincinnati, OH, USA
| | - Scott L Wexelblatt
- Perinatal Institute, Division of Neonatology, Cincinnati Children's Hospital Medical Center , Cincinnati, OH, USA.,Department of Pediatrics, College of Medicine, University of Cincinnati , Cincinnati, OH, USA.,Center for Addiction Research, College of Medicine, University of Cincinnati , Cincinnati, OH, USA
| | - Henry T Akinbi
- Perinatal Institute, Division of Neonatology, Cincinnati Children's Hospital Medical Center , Cincinnati, OH, USA.,Department of Pediatrics, College of Medicine, University of Cincinnati , Cincinnati, OH, USA
| | - Alexander A Vinks
- Division of Clinical Pharmacology, Cincinnati Children's Hospital Medical Center , Cincinnati, OH, USA.,Department of Pediatrics, College of Medicine, University of Cincinnati , Cincinnati, OH, USA.,Center for Addiction Research, College of Medicine, University of Cincinnati , Cincinnati, OH, USA
| | - Tomoyuki Mizuno
- Division of Clinical Pharmacology, Cincinnati Children's Hospital Medical Center , Cincinnati, OH, USA.,Department of Pediatrics, College of Medicine, University of Cincinnati , Cincinnati, OH, USA.,Center for Addiction Research, College of Medicine, University of Cincinnati , Cincinnati, OH, USA
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A Survey of Molecular Imaging of Opioid Receptors. Molecules 2019; 24:molecules24224190. [PMID: 31752279 PMCID: PMC6891617 DOI: 10.3390/molecules24224190] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 11/11/2019] [Accepted: 11/13/2019] [Indexed: 01/09/2023] Open
Abstract
The discovery of endogenous peptide ligands for morphine binding sites occurred in parallel with the identification of three subclasses of opioid receptor (OR), traditionally designated as μ, δ, and κ, along with the more recently defined opioid-receptor-like (ORL1) receptor. Early efforts in opioid receptor radiochemistry focused on the structure of the prototype agonist ligand, morphine, although N-[methyl-11C]morphine, -codeine and -heroin did not show significant binding in vivo. [11C]Diprenorphine ([11C]DPN), an orvinol type, non-selective OR antagonist ligand, was among the first successful PET tracers for molecular brain imaging, but has been largely supplanted in research studies by the μ-preferring agonist [11C]carfentanil ([11C]Caf). These two tracers have the property of being displaceable by endogenous opioid peptides in living brain, thus potentially serving in a competition-binding model. Indeed, many clinical PET studies with [11C]DPN or [11C]Caf affirm the release of endogenous opioids in response to painful stimuli. Numerous other PET studies implicate μ-OR signaling in aspects of human personality and vulnerability to drug dependence, but there have been very few clinical PET studies of μORs in neurological disorders. Tracers based on naltrindole, a non-peptide antagonist of the δ-preferring endogenous opioid enkephalin, have been used in PET studies of δORs, and [11C]GR103545 is validated for studies of κORs. Structures such as [11C]NOP-1A show selective binding at ORL-1 receptors in living brain. However, there is scant documentation of δ-, κ-, or ORL1 receptors in healthy human brain or in neurological and psychiatric disorders; here, clinical PET research must catch up with recent progress in radiopharmaceutical chemistry.
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Seah S, Asad ABA, Baumgartner R, Feng D, Williams DS, Manigbas E, Beaver JD, Reese T, Henry B, Evelhoch JL, Chin CL. Investigation of cross-species translatability of pharmacological MRI in awake nonhuman primate - a buprenorphine challenge study. PLoS One 2014; 9:e110432. [PMID: 25337714 PMCID: PMC4206294 DOI: 10.1371/journal.pone.0110432] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 09/22/2014] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Pharmacological MRI (phMRI) is a neuroimaging technique where drug-induced hemodynamic responses can represent a pharmacodynamic biomarker to delineate underlying biological consequences of drug actions. In most preclinical studies, animals are anesthetized during image acquisition to minimize movement. However, it has been demonstrated anesthesia could attenuate basal neuronal activity, which can confound interpretation of drug-induced brain activation patterns. Significant efforts have been made to establish awake imaging in rodents and nonhuman primates (NHP). Whilst various platforms have been developed for imaging awake NHP, comparison and validation of phMRI data as translational biomarkers across species remain to be explored. METHODOLOGY We have established an awake NHP imaging model that encompasses comprehensive acclimation procedures with a dedicated animal restrainer. Using a cerebral blood volume (CBV)-based phMRI approach, we have determined differential responses of brain activation elicited by the systemic administration of buprenorphine (0.03 mg/kg i.v.), a partial µ-opioid receptor agonist, in the same animal under awake and anesthetized conditions. Additionally, region-of-interest analyses were performed to determine regional drug-induced CBV time-course data and corresponding area-under-curve (AUC) values from brain areas with high density of µ-opioid receptors. PRINCIPAL FINDINGS In awake NHPs, group-level analyses revealed buprenorphine significantly activated brain regions including, thalamus, striatum, frontal and cingulate cortices (paired t-test, versus saline vehicle, p<0.05, n = 4). This observation is strikingly consistent with µ-opioid receptor distribution depicted by [6-O-[(11)C]methyl]buprenorphine ([(11)C]BPN) positron emission tomography imaging study in baboons. Furthermore, our findings are consistent with previous buprenorphine phMRI studies in humans and conscious rats which collectively demonstrate the cross-species translatability of awake imaging. Conversely, no significant change in activated brain regions was found in the same animals imaged under the anesthetized condition. CONCLUSIONS Our data highlight the utility and importance of awake NHP imaging as a translational imaging biomarker for drug research.
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Affiliation(s)
- Stephanie Seah
- Imaging, Merck & Co. Inc., West Point, Pennsylvania, United States of America
- Translational Medicine Research Centre, MSD, Singapore, Singapore
| | - Abu Bakar Ali Asad
- Imaging, Merck & Co. Inc., West Point, Pennsylvania, United States of America
- Translational Medicine Research Centre, MSD, Singapore, Singapore
| | - Richard Baumgartner
- Biostatistics and Research Decision Sciences, Merck & Co. Inc., Rahway, New Jersey, United States of America
| | - Dai Feng
- Biostatistics and Research Decision Sciences, Merck & Co. Inc., Rahway, New Jersey, United States of America
| | - Donald S. Williams
- Imaging, Merck & Co. Inc., West Point, Pennsylvania, United States of America
| | | | | | - Torsten Reese
- Translational Medicine Research Centre, MSD, Singapore, Singapore
| | - Brian Henry
- Translational Medicine Research Centre, MSD, Singapore, Singapore
| | - Jeffrey L. Evelhoch
- Imaging, Merck & Co. Inc., West Point, Pennsylvania, United States of America
| | - Chih-Liang Chin
- Imaging, Merck & Co. Inc., West Point, Pennsylvania, United States of America
- Translational Medicine Research Centre, MSD, Singapore, Singapore
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Schoultz BW, Hjørnevik T, Reed BJ, Marton J, Coello CS, Willoch F, Henriksen G. Synthesis and evaluation of three structurally related ¹⁸F-labeled orvinols of different intrinsic activities: 6-O-[¹⁸F]fluoroethyl-diprenorphine ([¹⁸F]FDPN), 6-O-[¹⁸F]fluoroethyl-buprenorphine ([¹⁸F]FBPN), and 6-O-[¹⁸F]fluoroethyl-phenethyl-orvinol ([¹⁸F]FPEO). J Med Chem 2014; 57:5464-9. [PMID: 24933507 DOI: 10.1021/jm500503k] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We report the synthesis and biological evaluation of a triplet of 6-O-(18)F-fluoroethylated derivatives of structurally related orvinols that span across the full range of intrinsic activities, the antagonist diprenorphine, the partial agonist buprenorphine, and the full agonist phenethyl-orvinol. [(18)F]fluoroethyl-diprenorphine, [(18)F]fluoroethyl-buprenorphine, and [(18)F]fluoroethyl-phenethyl-orvinol were prepared in high yields and quality from their 6-O-desmethyl-precursors. The results indicate suitable properties of the three 6-O-(18)F-fluoroethylated derivatives as functional analogues to the native carbon-11 labeled versions with similar pharmacological properties.
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Affiliation(s)
- Bent W Schoultz
- Department of Chemistry, University of Oslo , P.O. Box 1033, Blindern, N-0315 Oslo, Norway
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Malcolm-Smith S, Thomas KGF, Ipser J, Stein D, van Honk J, Solms M. Opioid Function Is Dysregulated Subsequent to Early Social Trauma: Healthy Young Adults’ Response to a Buprenorphine Challenge. ACTA ACUST UNITED AC 2013. [DOI: 10.1080/15294145.2013.10799826] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Design and synthesis of an ¹⁸F-labeled version of phenylethyl orvinol ([¹⁸F]FE-PEO) for PET-imaging of opioid receptors. Molecules 2012; 17:11554-69. [PMID: 23023682 PMCID: PMC6268392 DOI: 10.3390/molecules171011554] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Revised: 09/10/2012] [Accepted: 09/11/2012] [Indexed: 11/23/2022] Open
Abstract
The semisynthetic oripavine derivative phenethyl orvinol (PEO), a full agonist at opioid receptors (OR), is an attractive structural motif for developing 18F-labeled PET tracers with a high degree of sensitivity for competition between endogenous and exogenous OR-ligands. The target cold reference compound 6-O-(2-fluoroethyl)-6-O-desmethylphenylethyl orvinol (FE-PEO) was obtained via two separate reaction routes. A three-step synthesis was developed for the preparation of a tosyloxyethyl precursor (TE-TDPEO), the key precursor for a direct, nucleophilic radiofluorination to yield [18F]FE-PEO. The developed radiosynthesis provides the target compound in relevantly high yield and purity, and is adaptable to routine production.
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Blum K, Chen TJH, Bailey J, Bowirrat A, Femino J, Chen ALC, Simpatico T, Morse S, Giordano J, Damle U, Kerner M, Braverman ER, Fornari F, Downs BW, Rector C, Barh D, Oscar-Berman M. Can the chronic administration of the combination of buprenorphine and naloxone block dopaminergic activity causing anti-reward and relapse potential? Mol Neurobiol 2011; 44:250-68. [PMID: 21948099 DOI: 10.1007/s12035-011-8206-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 09/07/2011] [Indexed: 01/21/2023]
Abstract
Opiate addiction is associated with many adverse health and social harms, fatal overdose, infectious disease transmission, elevated health care costs, public disorder, and crime. Although community-based addiction treatment programs continue to reduce the harms of opiate addiction with narcotic substitution therapy such as methadone maintenance, there remains a need to find a substance that not only blocks opiate-type receptors (mu, delta, etc.) but also provides agonistic activity; hence, the impetus arose for the development of a combination of narcotic antagonism and mu receptor agonist therapy. After three decades of extensive research, the federal Drug Abuse Treatment Act 2000 (DATA) opened a window of opportunity for patients with addiction disorders by providing increased access to options for treatment. DATA allows physicians who complete a brief specialty-training course to become certified to prescribe buprenorphine and buprenorphine/naloxone (Subutex, Suboxone) for treatment of patients with opioid dependence. Clinical studies indicate that buprenorphine maintenance is as effective as methadone maintenance in retaining patients in substance abuse treatment and in reducing illicit opioid use. With that stated, we must consider the long-term benefits or potential toxicity attributed to Subutex or Suboxone. We describe a mechanism whereby chronic blockade of opiate receptors, in spite of only partial opiate agonist action, may ultimately block dopaminergic activity causing anti-reward and relapse potential. While the direct comparison is not as yet available, toxicity to buprenorphine can be found in the scientific literature. In considering our cautionary note in this commentary, we are cognizant that, to date, this is what we have available, and until such a time when the real magic bullet is discovered, we will have to endure. However, more than anything else this commentary should at least encourage the development of thoughtful new strategies to target the specific brain regions responsible for relapse prevention.
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Affiliation(s)
- Kenneth Blum
- Department of Psychiatry and McKnight Brain Institute, University of Florida College of Medicine, Gainesville, FL 32610, USA.
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13
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Pike VW, Rash KS, Chen Z, Pedregal C, Statnick MA, Kimura Y, Hong J, Zoghbi SS, Fujita M, Toledo MA, Diaz N, Gackenheimer SL, Tauscher JT, Barth VN, Innis RB. Synthesis and evaluation of radioligands for imaging brain nociceptin/orphanin FQ peptide (NOP) receptors with positron emission tomography. J Med Chem 2011; 54:2687-700. [PMID: 21438532 PMCID: PMC3081360 DOI: 10.1021/jm101487v] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Positron emission tomography (PET) coupled to an effective radioligand could provide an important tool for understanding possible links between neuropsychiatric disorders and brain NOP (nociceptin/orphanin FQ peptide) receptors. We sought to develop such a PET radioligand. High-affinity NOP ligands were synthesized based on a 3-(2'-fluoro-4',5'-dihydrospiro[piperidine-4,7'-thieno[2,3-c]pyran]-1-yl)-2(2-halobenzyl)-N-alkylpropanamide scaffold and from experimental screens in rats, with ex vivo LC-MS/MS measures, three ligands were identified for labeling with carbon-11 and evaluation with PET in monkey. Each ligand was labeled by (11)C-methylation of an N-desmethyl precursor and studied in monkey under baseline and NOP receptor-preblock conditions. The three radioligands, [(11)C](S)-10a-c, gave similar results. Baseline scans showed high entry of radioactivity into the brain to give a distribution reflecting that expected for NOP receptors. Preblock experiments showed high early peak levels of brain radioactivity, which rapidly declined to a much lower level than seen in baseline scans, thereby indicating a high level of receptor-specific binding in baseline experiments. Overall, [(11)C](S)-10c showed the most favorable receptor-specific signal and kinetics and is now selected for evaluation in human subjects.
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Affiliation(s)
- Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States.
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14
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Yassen A, Olofsen E, van Dorp E, Sarton E, Teppema L, Danhof M, Dahan A. Mechanism-based pharmacokinetic-pharmacodynamic modelling of the reversal of buprenorphine-induced respiratory depression by naloxone : a study in healthy volunteers. Clin Pharmacokinet 2008; 46:965-80. [PMID: 17922561 DOI: 10.2165/00003088-200746110-00004] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
BACKGROUND AND OBJECTIVE Respiratory depression is a potentially life-threatening adverse effect of opioid therapy. It has been postulated that the difficulty of reversing buprenorphine-induced respiratory depression is caused by slow receptor association-dissociation kinetics at the opioid mu receptor. The aim of this study was to characterise the pharmacodynamic interaction between buprenorphine and naloxone in healthy volunteers. METHODS A competitive pharmacodynamic interaction model was proposed to describe and predict the time course of naloxone-induced reversal of respiratory depression. The model was identified using data from an adaptive naloxone dose-selection trial following intravenous administration of buprenorphine 0.2mg/70kg or 0.4mg/70kg. RESULTS The pharmacokinetics of naloxone and buprenorphine were best described by a two-compartment model and a three-compartment model, respectively. A combined biophase equilibration-receptor association-dissociation pharmacodynamic model described the competitive interaction between buprenorphine and naloxone at the opioid mu receptor. For buprenorphine, the values of the rate constants of receptor association (k(on)) and dissociation (k(off)) were 0.203 mL/ng/min and 0.0172 min(-)(1), respectively. The value of the equilibrium dissociation constant (K(D)) was 0.18 nmol/L. The half-life (t((1/2))) of biophase equilibration was 173 minutes. These estimates of the pharmacodynamic parameters are similar to values obtained in the absence of naloxone co-administration. For naloxone, the half-life of biophase distribution was 6.5 minutes. CONCLUSIONS Because of the slow receptor association-dissociation kinetics of buprenorphine in combination with the fast elimination kinetics of naloxone, naloxone is best administered as a continuous infusion for reversal of buprenorphine-induced respiratory depression.
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Affiliation(s)
- Ashraf Yassen
- Division of Pharmacology, Leiden/Amsterdam Centre for Drug Research, Leiden, The Netherlands
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15
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Wu CH, Yang SC, Wang YS, Chen BG, Lin CC, Liu RH. Evaluation of various derivatization approaches for gas chromatography–mass spectrometry analysis of buprenorphine and norbuprenorphine. J Chromatogr A 2008; 1182:93-112. [DOI: 10.1016/j.chroma.2007.11.063] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2007] [Revised: 11/18/2007] [Accepted: 11/22/2007] [Indexed: 01/31/2023]
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Boutin H, Catherine A, Mackenzie ET, Jauzac P, Dauphin F. Long-term alterations in mu, delta and kappa opioidergic receptors following middle cerebral artery occlusion in mice. Acta Neuropathol 2007; 114:491-500. [PMID: 17676326 DOI: 10.1007/s00401-007-0269-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2006] [Revised: 07/02/2007] [Accepted: 07/05/2007] [Indexed: 12/15/2022]
Abstract
Alterations in the opioidergic system may play a role in the molecular mechanisms underlying neurochemical responses to cerebral ischaemia. The present study aimed to determine the delayed expression of mu, delta and kappa opioid receptors, following 1, 2, 7, and 30 days of middle cerebral artery occlusion (MCAO) in mice. Using quantitative autoradiography, we highlighted significant decreases in mu, delta and kappa opioid receptor expression in ipsilateral cortices from day 1 post-MCAO. Moreover, in contralateral nucleus lateralis thalami pars posterior, ipsi- and contralateral nucleus medialis dorsalis thalami, and ipsilateral substantia nigra, pars reticulata (SNr), kappa receptors were increased; mu receptor densities were decreased in nucleus ventralis thalami, pars posterior (VThP), and SNr. delta-Binding sites were increased in the striatum on day 30 post-MCAO. The alterations in opioid receptors in cortical infarcts were correlated with strong histological damage. Further reductions in opioid receptor densities in cortical infarcts were observed at later time points. In subcortical brain regions, opioid receptor densities were also altered but no histological damage was seen, except in the VThP, in which cell density was increased on day 30. Delayed reductions in opioid receptor densities in the infarct appeared as the continuation of the early processes previously demonstrated. However, changes in subcortical opioid receptor expression may correlate with neuronal alterations in remote brain regions. Changes in opioidergic receptor expression in these regions may be involved in the long-term consequences of stroke and could be used as biomarker of neuronal alteration through the use of imaging techniques in the clinic.
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MESH Headings
- Animals
- Binding Sites/physiology
- Biomarkers/analysis
- Biomarkers/metabolism
- Brain/metabolism
- Brain/pathology
- Brain/physiopathology
- Brain Infarction/metabolism
- Brain Infarction/pathology
- Brain Infarction/physiopathology
- Brain Ischemia/metabolism
- Brain Ischemia/pathology
- Brain Ischemia/physiopathology
- Disease Models, Animal
- Disease Progression
- Down-Regulation/physiology
- Infarction, Middle Cerebral Artery/metabolism
- Infarction, Middle Cerebral Artery/pathology
- Infarction, Middle Cerebral Artery/physiopathology
- Mice
- Nerve Degeneration/metabolism
- Nerve Degeneration/pathology
- Nerve Degeneration/physiopathology
- Opioid Peptides/metabolism
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, kappa/metabolism
- Receptors, Opioid, mu/metabolism
- Time
- Time Factors
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Biswal S, Resnick DL, Hoffman JM, Gambhir SS. Molecular Imaging: Integration of Molecular Imaging into the Musculoskeletal Imaging Practice. Radiology 2007; 244:651-71. [PMID: 17709823 DOI: 10.1148/radiol.2443060295] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Chronic musculoskeletal diseases such as arthritis, malignancy, and chronic injury and/or inflammation, all of which may produce chronic musculoskeletal pain, often pose challenges for current clinical imaging methods. The ability to distinguish an acute flare from chronic changes in rheumatoid arthritis, to survey early articular cartilage breakdown, to distinguish sarcomatous recurrence from posttherapeutic inflammation, and to directly identify generators of chronic pain are a few examples of current diagnostic limitations. There is hope that a growing field known as molecular imaging will provide solutions to these diagnostic puzzles. These techniques aim to depict, noninvasively, specific abnormal cellular, molecular, and physiologic events associated with these and other diseases. For example, the presence and mobilization of specific cell populations can be monitored with molecular imaging. Cellular metabolism, stress, and apoptosis can also be followed. Furthermore, disease-specific molecules can be targeted, and particular gene-related events can be assayed in living subjects. Relatively recent molecular and cellular imaging protocols confirm important advances in imaging technology, engineering, chemistry, molecular biology, and genetics that have coalesced into a multidisciplinary and multimodality effort. Molecular probes are currently being developed not only for radionuclide-based techniques but also for magnetic resonance (MR) imaging, MR spectroscopy, ultrasonography, and the emerging field of optical imaging. Furthermore, molecular imaging is facilitating the development of molecular therapies and gene therapy, because molecular imaging makes it possible to noninvasively track and monitor targeted molecular therapies. Implementation of molecular imaging procedures will be essential to a clinical imaging practice. With this in mind, the goal of the following discussion is to promote a better understanding of how such procedures may help address specific musculoskeletal issues, both now and in the years ahead.
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Affiliation(s)
- Sandip Biswal
- Department of Radiology, Molecular Imaging Program, Stanford University School of Medicine, 300 Pasteur Dr, S-062B, Stanford, CA 94305, USA.
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18
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Yassen A, Olofsen E, Romberg R, Sarton E, Teppema L, Danhof M, Dahan A. Mechanism-based PK/PD Modeling of the Respiratory Depressant Effect of Buprenorphine and Fentanyl in Healthy Volunteers. Clin Pharmacol Ther 2007; 81:50-8. [PMID: 17185999 DOI: 10.1038/sj.clpt.6100025] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The objective of this study was to characterize the pharmacokinetic/pharmacodynamic (PK/PD) relationship of buprenorphine and fentanyl for the respiratory depressant effect in healthy volunteers. Data on the time course of the ventilatory response at a fixed P(ET)CO(2) of 50 mm Hg and P(ET)O(2) of 110 mm Hg following intravenous administration of buprenorphine and fentanyl were obtained from two phase I studies (50 volunteers received buprenorphine: 0.05-0.6 mg/70 kg and 24 volunteers received fentanyl: 0.075-0.5 mg/70 kg). The PK/PD correlations were analyzed using nonlinear mixed effects modeling. A two- and three-compartment pharmacokinetic model characterized the time course of fentanyl and buprenorphine concentration, respectively. Three structurally different PK/PD models were evaluated for their appropriateness to describe the time course of respiratory depression: (1) a biophase distribution model with a fractional sigmoid E(max) pharmacodynamic model, (2) a receptor association/dissociation model with a linear transduction function, and (3) a combined biophase distribution-receptor association/dissociation model with a linear transduction function. The results show that for fentanyl hysteresis is entirely determined by the biophase distribution kinetics, whereas for buprenorphine hysteresis is caused by a combination of biophase distribution kinetics and receptor association/dissociation kinetics. The half-time values of biophase equilibration (t(1/2, k(eo))) were 16.4 and 75.3 min for fentanyl and buprenorphine, respectively. In addition, for buprenorphine, the value of k(on) was 0.246 ml/ng/min and the value of k(off) was 0.0102 min(-1). The concentration-effect relationship of buprenorphine was characterized by a ceiling effect at higher concentrations (intrinsic activity alpha=0.56, 95% confidence interval (CI): 0.50-0.62), whereas fentanyl displayed full respiratory depressant effect (alpha=0.91, 95% CI: 0.19-1.62).
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Affiliation(s)
- A Yassen
- Department of Pharmacology, Leiden/Amsterdam Center for Drug Research, Leiden, The Netherlands
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Yassen A, Olofsen E, Kan J, Dahan A, Danhof M. Animal-to-Human Extrapolation of the Pharmacokinetic and Pharmacodynamic Properties of Buprenorphine. Clin Pharmacokinet 2007; 46:433-47. [PMID: 17465641 DOI: 10.2165/00003088-200746050-00005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
OBJECTIVES This investigation describes the interspecies scaling of the pharmacokinetics and pharmacodynamics of buprenorphine. METHODS Data on the time course of the antinociceptive and respiratory depressant effects of buprenorphine in rats and in humans were simultaneously analysed on the basis of a mechanism-based pharmacokinetic-pharmacodynamic model. RESULTS An allometric three-compartment pharmacokinetic model described the time course of the concentration in plasma. The value of the allometric coefficient for clearance was 35.2 mL/min (relative standard error [RSE] = 5.6%) and the value of the allometric exponent was 0.76 (RSE 5.61%). A combined biophase distribution-receptor association/dissociation model with a linear transduction function described hysteresis between plasma concentration and effect. The values of the drug-specific pharmacodynamic parameters were identical in rats and in humans. For the respiratory depressant effect, the values of the second-order rate constant of receptor association (k(on)) and the first-order rate constant of receptor dissociation (k(off)) were 0.23 mL/ng/min (RSE = 15.8%) and 0.014 min(-1) (RSE = 27.7%), respectively, and the value of the equilibrium dissociation constant (K(diss)) was 0.13 nmol/L. The value of the intrinsic activity alpha was 0.52 (RSE = 3.4%). For the antinociceptive effect, the values of the k(on) and k(off) were 0.015 mL/ng/min (RSE = 18.3%) and 0.053 min(-1) (RSE = 23.1%), respectively. The value of the K(diss) was 7.5 nmol/L. An allometric equation described the scaling of the system-specific parameter, the first-order distribution rate constant (k(e0)). The value of the allometric coefficient for the k(e0) was 0.0303 min(-1) (RSE = 11.3%) and the value of the exponent was -0.28 (RSE = 9.6%). CONCLUSIONS The different values of the drug-specific pharmacodynamic parameters are consistent with the different opioid mu receptor subtypes involved in the antinociceptive and respiratory depressant effects.
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Affiliation(s)
- Ashraf Yassen
- Leiden/Amsterdam Center for Drug Research, Division of Pharmacology, Gorleaus Laboratories, Leiden, The Netherlands
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20
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Yassen A, Kan J, Olofsen E, Suidgeest E, Dahan A, Danhof M. Mechanism-based pharmacokinetic-pharmacodynamic modeling of the respiratory-depressant effect of buprenorphine and fentanyl in rats. J Pharmacol Exp Ther 2006; 319:682-92. [PMID: 16855177 DOI: 10.1124/jpet.106.107953] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The purpose of this investigation was to develop a mechanism-based pharmacokinetic/pharmacodynamic (PK/PD) model to predict the time course of respiratory depression following administration of opioids in rats. The proposed model is based on receptor theory and aims at the separate characterization of biophase distribution and receptor association/dissociation kinetics as determinants of hysteresis between plasma concentration and effect. Individual concentration time courses of buprenorphine and fentanyl were determined in conjunction with continuous monitoring of respiratory depression. Buprenorphine and fentanyl were administered intravenously in various doses. For buprenorphine hysteresis was best described by a combined biophase distribution-receptor association/dissociation model with a linear transducer function. The values of the parameter estimates of the rate constants for biophase distribution (k(eo)), receptor association (k(on)), and dissociation (k(off)) were 0.0348 min(-1) [95% confidence interval (CI), 0.0193-0.0503 min(-1)], 0.57 ml/ng/min (95% CI, 0.38-0.76 ml/ng/min), and 0.0903 min(-1) (95% CI, 0.035-0.196 min(-1)), respectively. The values of the equilibrium dissociation constant and intrinsic activity were 0.16 ng/ml and 0.48 (95% CI, 0.45-0.51), respectively. The value of the K(d) is close to reported estimates of receptor affinity in vitro confirming the validity of the mechanism-based PK/PD model. For fentanyl, unrealistically high estimates of the rate constants for receptor association and dissociation were obtained, indicating that hysteresis is caused solely by biophase distribution kinetics. This is consistent with fentanyl's fast receptor association/dissociation kinetics in vitro. As a result, the mechanism-based PK/PD model of fentanyl could be reduced to a biophase distribution model with fractional sigmoid E(max) pharmacodynamic model.
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Affiliation(s)
- Ashraf Yassen
- Leiden/Amsterdam Center for Drug Research, Division of Pharmacology, Gorlaeus Laboratories, P.O. Box 9502, 2300 RA Leiden, The Netherlands
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21
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Englberger W, Kögel B, Friderichs E, Strassburger W, Germann T. Reversibility of opioid receptor occupancy of buprenorphine in vivo. Eur J Pharmacol 2006; 534:95-102. [PMID: 16490191 DOI: 10.1016/j.ejphar.2006.01.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2005] [Revised: 12/22/2005] [Accepted: 01/10/2006] [Indexed: 11/17/2022]
Abstract
The slow association and incomplete dissociation of buprenorphine from opioid receptors observed in vitro have been suggested to reduce the accessibility of opioid receptors in vivo. If so, it might be expected that buprenorphine continues to occupy opioid receptors long after the antinociceptive activity has dissipated. To examine this hypothesis, buprenorphine (46.4 microg/kg i.v.) was administered to rats 1, 2, 4 or 8 h before isolation of their forebrain membranes and the maximal binding capacity (Bmax) for [3H]-[D-Ala2, N-methyl-Phe4-Gly5-ol]-enkephalin ([3H]DAMGO) was determined to measure the number of mu-opioid receptor binding sites remaining. Extent and duration of the reduction of Bmax by buprenorphine (ED50 11.2 microg/kg 1 h post-application) correlated with the antinociceptive activity in the rat tail flick (ED50 16.4 microg/kg i.v. 1 h post-application). At 8 h after administration there was still residual antinociception but no further attenuation of Bmax was detectable. Thus receptor occupancy by buprenorphine does not cause impairment of mu-opioid receptor accessibility beyond the duration of its antinociceptive activity. Therefore, no impairment of antinociception in the case of an opioid switch is to be expected.
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Affiliation(s)
- Werner Englberger
- Department of Molecular Pharmacology, Research Center, Grünenthal GmbH, Aachen, Germany
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22
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Megarbane B, Pirnay S, Borron SW, Trout H, Monier C, Risède P, Boschi G, Baud FJ. Flunitrazepam does not alter cerebral distribution of buprenorphine in the rat. Toxicol Lett 2005; 157:211-9. [PMID: 15917146 DOI: 10.1016/j.toxlet.2005.02.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2004] [Revised: 02/16/2005] [Accepted: 02/17/2005] [Indexed: 10/25/2022]
Abstract
Deaths have been reported among heroin addicts related to combined buprenorphine and flunitrazepam use. The aim of this study was to determine the existence of a drug-drug interaction during the distribution phase of buprenorphine. Arterial blood gases were measured after intravenous administration of buprenorphine alone (30 mg/kg), flunitrazepam alone (40 mg/kg) or both drugs in rats. Buprenorphine kinetics was studied in plasma and in striatum using cerebral microdialysis, both alone and after rat pretreatment with flunitrazepam. In contrast to buprenorphine or flunitrazepam alone, buprenorphine in combination with flunitrazepam induced a significant, rapid and sustained respiratory depression. Arterial PCO2 was increased at 1.5 min (6.7+/-0.2 versus 5.4+/-0.3 and 5.5+/-0.3 kPa, respectively, P=0.04) (mean+/-S.E.M.), and arterial pH decreased (7.37+/-0.02 versus 7.45+/-0.02 and 7.45+/-0.01, respectively, P=0.03). Plasma buprenorphine kinetics was well described by a three-compartment linear model, with a distribution half-life of 7.4+/-2.7 min and an elimination half-life of 463.9+/-152.3 min. However, neither plasma nor striatal buprenorphine kinetics were significantly altered by pre-administration of flunitrazepam. The adverse interaction between flunitrazepam and buprenorphine cannot be explained by a pharmacokinetic drug-drug interaction during the distribution phase of buprenorphine.
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Affiliation(s)
- Bruno Megarbane
- INSERM U26, Université Paris VII, Hôpital Fernand Widal, Réanimation Médicale et Toxicologique-INSERM U26, Hôpital Lariboisière, 2 Rue Ambroise Paré, 75010 Paris, France.
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Shiue CY, Welch MJ. Update on PET radiopharmaceuticals: life beyond fluorodeoxyglucose. Radiol Clin North Am 2004; 42:1033-53, viii. [PMID: 15488556 DOI: 10.1016/j.rcl.2004.08.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Twenty-eight years after its inception, 2-[18F]FDG- is still the most widely used radiopharmaceutical for PET studies, but numerous more specific radiotracers have been developed and applied in neuroscience and oncology. The advances in radiotracer chemistry, especially the nucleophilic substitution reaction, have played the pivotal role in synthesizing various no-carrier-added 18F-labeled radiotracers for PET studies of various receptor systems. This article lists some of the radiotracers that are available for PET studies in neuroscience and oncology. The prospects for developing other new radiotracers for imaging other organ diseases also seem to be promising.
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Affiliation(s)
- Chyng-Yann Shiue
- Department of Radiology, University of Pennsylvania School of Medicine, 1 Silverstein, 3400 Spruce Street, Philadelphia, PA 19104, USA.
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Abstract
Over the past 30 years, advances in radiotracer chemistry and positron emission tomography instrumentation have merged to make positron emission tomography a powerful scientific tool in the biomedical sciences. However, despite the increasing reliance of the biomedical sciences on imaging and the new needs for functional information created by the sequencing of the human genome, the development of new radiotracers with the specificity and kinetic characteristics for quantitative analysis in vivo remains a slow process. In this article, we focus on advances in the development of the radiotracers involved in neurotransmission, amino acid transport, protein synthesis, and DNA synthesis. We conclude with a brief section on newer radiotracers that image other molecular targets and conclude with a summary of some of the scientific and infrastructure needs that would expedite the development and introduction of new radiotracers into biomedical research and the practice of medicine.
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Affiliation(s)
- Joanna S Fowler
- Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, USA
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Greer PJ, Villemagne VL, Ruszkiewicz J, Graves AK, Meltzer CC, Mathis CA, Price JC. MR atlas of the baboon brain for functional neuroimaging. Brain Res Bull 2002; 58:429-38. [PMID: 12183022 DOI: 10.1016/s0361-9230(02)00810-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mathematical co-registration of functional image data (e.g., positron emission tomography, PET) to anatomical magnetic resonance (MR) imaging data allows for objective associations between function and anatomy. Baboons are often used as non-human primate models for functional neuroimaging studies. In this work, a digital MR-based high-resolution atlas of the baboon brain was generated and evaluated for PET. The atlas was generated from six SPGR-MR datasets (centered at mid-sagittal line, AC-PC orientation) that were transformed into the space of one representative MR, averaged and resampled into PET space. The atlas was evaluated by comparing blood flow and dopamine receptor and serotonin transporter binding measures determined using regions-of-interest (ROIs) generated on each individual co-registered MR (ROI(i)) and the atlas-defined ROI template (ROI(ATLAS)). Common ROIs applied to all data included frontal cortex, temporal cortex, thalamus, caudate, putamen and cerebellum. High correlations (r(2)>0.87) were found between the ROI(i) and ROI(ATLAS) data for all radiotracers (linear regression across ROIs for each baboon). The average regression slope values ranged from 0.95 to 1.02 across radiotracers. Lastly, use of the atlas for statistical parametric mapping (SPM) of [15O]water data yielded good agreement with previous ROI(i) results. Overall, the digital MR-based atlas allowed for automatic co-registration, proved useful across a range of PET Studies, and is accessible electronically via the Internet.
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Affiliation(s)
- Phil J Greer
- University of Pittsburgh PET Facility, Pittsburgh, PA 15213-2582, USA
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Use of Positron Emission Tomography to Measure Brain Activity Responses to Fentanyl Analgesia. CURRENT REVIEW OF PAIN 2000; 3:359-366. [PMID: 10998692 DOI: 10.1007/s11916-999-0078-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
This review illustrates the potential of positron emission tomography (PET) in elucidating the supraspinal analgesic mechanisms of opioids in humans. First, a range of PET methodologies, available for functional brain mapping both on the receptor and neuronal network level in humans, is examined briefly. Subsequently, studies that have taken advantage of only a small portion of these PET techniques are reviewed. In light of the limitations of these experiments, a series of strategies is discussed that, by exploiting the full arsenal of PET techniques, could provide unique insights into the supraspinal mechanisms of opioid analgesia under the clinically most relevant circumstances--in the living human brain.
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Organization of Opioid Receptors in Human Brain and Drug Interactions Studied by PET and SPECT Imaging: Implications for Treatment Strategies for Opiate Addiction. ACTA ACUST UNITED AC 1997. [DOI: 10.1006/smns.1997.0113] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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