Pilot Study of a Multi-System Analysis of Opioid Receptor Binding

  • End date
    Sep 23, 2025
  • participants needed
  • sponsor
    University of Pennsylvania
Updated on 23 October 2022
Accepts healthy volunteers


This study in up to 20 healthy subjects (including 10 females and 10 males) will use [11C]carfentanil whole-body PET imaging to examine the CNS and broader systemic opioid binding and its blockade by the non-selective opioid antagonist naloxone administered parenterally in 2 scan sessions, which can be done the same day or on different days.


This study in up to 20 healthy subjects (including 10 females and 10 males) will use [11C]carfentanil whole-body PET imaging to examine the CNS and broader systemic opioid binding and its blockade by the non-selective opioid antagonist naloxone administered parenterally in 2 scan sessions, which can be done the same day or on different days. Findings from this study will demonstrate the distribution of opioid effects in brain and other organs and provide a frame of reference for subsequent studies that use a similar approach in individuals with opioid use disorder (OUD), including those being treated with opioid agonist or antagonist therapies and individuals with chronic pain. Thus, this project will inform clinically relevant questions related to OUD and chronic pain.

PET/CT imaging will be used to evaluate the distribution of opioid effects in the brain and other organs using the investigational radiotracer [11C]carfentanil. Each subject will have two [11C]carfentanil positron emission tomography/computed tomography (PET/CT) scans performed, one of which will include pretreatment with parenteral naloxone.

Two positron emission tomography (PET) studies in which we will measure MOR BPND: (1) following the administration of [11C]carfentanil alone and (2) following the administration of naloxone followed by [11C]carfentanil. The scan sessions will be held 1 day to 6 weeks apart. Analyses will compare the BPND in the brain and other regions of the body before and after the administration of naloxone. A structural MRI scan of the brain and spinal cord will be conducted before the PET scan to permit co-registration and the identification of specific brain regions on PET scan.

During each PET scan, participants will undergo approximately 90 minutes of dynamic scanning of the brain and body in a whole-body PET/CT scanner. PET/CT imaging sessions will include an injection of ≤ 15 mCi (approximate range for most studies is anticipated to be 5-15 mCi) of [11C]carfentanil. Before one of the scan sessions a dose of naloxone will be injected intravenously approximately 10 minutes before the [11C]carfentanil injection. Data will be collected to evaluate the uptake of [11C]carfentanil in the brain and other organs with and without naloxone blockade. Venous blood samples will be taken during the scan session for measurement of radioactive counts and/or bio-metabolites.

Subjects are required to have a brain MRI performed within 1 year prior to study enrollment, or if the subject has not had a brain MRI that is deemed acceptable for use for this study they will be asked to undergo a research brain MRI after they have consented for this study.

Condition Healthy
Treatment Carfentanil, C-11
Clinical Study IdentifierNCT05528848
SponsorUniversity of Pennsylvania
Last Modified on23 October 2022


Yes No Not Sure

Inclusion Criteria

Healthy males and females, 18-50 years of age
Informed of the investigational nature of this study and able to provide written informed consent and participate in this study in accordance with institutional and federal guidelines prior to study-specific procedures
Fluent in English and able to provide written informed consent in English

Exclusion Criteria

Women who are pregnant or breast feeding will not be eligible for this study; a urine pregnancy test will be performed in women of child-bearing potential at screening and on the day of each of the PET/CT scans
Subjects who report claustrophobia, which in the opinion of an investigator would interfere with acquisition of the structural MRI required for PET co-registration, and/or the PET scan itself
Contraindications to MRI (e.g., metal in the body that cannot be removed and is not MRI compatible). An MRI screening form will be completed during screening
History of or current major DSM-5 Axis 1 psychiatric diagnosis, as identified during psychiatric interview or mental status examination at screening/baseline
History of epilepsy or seizure disorder, head trauma or brain (CNS) tumor as assessed by medical record review and/or self-report
A history of substance abuse disorder (SUD) and /or current treatment for a SUD, including nicotine dependence
Self-reported current alcohol consumption that exceeds 14 standard drinks/week for men and 7 standard drinks/week for women
A breath alcohol concentration (BAC) reading > 0.01, a urine toxicology test positive for prohibited drugs or a positive CO breast test at any study visit
Current or use within past 12 months of any medications containing naltrexone or other MOR ligands (e.g., buprenorphine)
Current us or recent discontinuation (within 14 days of screening) of the following medications (Participants will be instructed to refrain from using any study-prohibited drugs, though participants will be allowed to take prescription medicines not on the exclusionary list throughout their participation in the study.)
Any form of smoking cessation medication
Any medication prescribed to treat alcohol use disorder or heavy drinking
Use within the past 12 months of psychotropic medications (antipsychotics
antidepressants, anti-anxiety medications, stimulants or opioid-containing
medications for pain for longer than one week)
Allergic reaction to any opioid or naloxone
Inability to tolerate imaging procedures in the opinion of an investigator or treating physician
Any current medical condition, illness, or disorder as assessed by medical record review and/or self-report that is considered by a physician or investigator to be a condition that could compromise participant safety or successful participation in the study or interfere with distribution of the radiotracer
Only individuals 18 years or older who can understand and give informed consent will be
able to participate in this study. All individuals will be told that their participation is
voluntary and they may withdraw from the study at any time. Individuals will also be
informed that no matter their decision, their access to clinical care at the University of
Pennsylvania or its affiliates will not be affected. This should negate any undue influence
or coercion. Children, fetuses, neonates, or prisoners are not included in this research
study. The menopausal status of female study participants will be reviewed during the
screening process by examining the patient's chart and/or by self-report. All women of
child-bearing potential will have a urine pregnancy test prior to injection of
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