HealthyPhase 1NCT05528848
Multi-System Analysis of Opioid Receptor Binding
A Phase 1 study testing Carfentanil, C-11, Naloxone and Loperamide Hydrochloride in people with Healthy and Opioid Use Disorder, run by University of Pennsylvania at 1 site in United States.
Trial summary
This study will enroll up to 60 adults (including 30 females and 30 males) in three cohorts of up to 20 subjects each. In all three groups, [11C]carfentanil whole-body PET imaging will be used to examine the central nervous system (CNS) and broader systemic opioid binding in an initial scan session. Read more about this study
- Who is it for?
- Ages 18 to 50 yearsHealthy volunteers can take part
- Conditions the study is for
- Healthy, Opioid Use Disorder
- What is being tested?
- Carfentanil, C-11, Naloxone and Loperamide Hydrochloride
- Type of treatment
- Pill or oral medicine, Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 25 participants
- Where
- 1 siteUnited States
- Study dates
- 20 Sep 2022to Sep 2027
- Phase
- Phase 1
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 50 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Cohort 1 (OUD+/MAT+):
- 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.
- OUD positive (+): Participants will meet DSM-5 criteria for a lifetime diagnosis of OUD and will be on a stable dosage of buprenorphine or methadone treatment for at least four weeks prior to the screening visit.
- Cohort 2 (OUD+/MAT-):
Show all 15Show fewer
- 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.
- OUD positive (+): Participants will meet DSM-5 criteria for a lifetime diagnosis of OUD, but cannot meet criteria for OUD in the 2 months prior to screening, has not used an opioid for any reason in the 30 days prior to screening as evidenced by self-report, medical record review, and urine drug testing at screening and and on the day of the PET scan, and has not received MAT for OUD during the 12 months prior to screening.
- Cohort 3 (OUD-, Healthy Controls):
- 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.
- OUD negative (-): Must never have met criteria for OUD (as per DSM-5) and cannot have used an opioid for any reason in the past 30 days prior to screening as evidenced by self-report, medical record review, and urine drug testing at screening.
Who cannot join
- Cohort 1 (OUD+/MAT+):
- 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.
- Current major DSM-5 Axis 1 psychiatric diagnosis that requires treatment with a medication that interferes with opioid receptor binding, 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
Show all 40Show fewer
- Current severe substance use disorder (SUD), other than OUD or, cannabis use disorder, with self-reported heavy drug use in the past 3 months and a positive urine toxicology screen for that drug (may be repeated once), and /or current pharmacological treatment for an SUD other than OUD that would interfere with study procedures and outcome.
- A breath alcohol concentration (BAC) reading > 0.01 or a urine toxicology test positive for prohibited drugs.
- Current use or recent discontinuation (within 14 days of screening) of medications that interfere with radiotracer binding. Participants will be instructed to refrain from using any study-prohibited drugs, though participants will be allowed to take prescription medicines that are not exclusionary throughout their participation in the study.
- 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.
- Cohort 2 (OUD+/MAT-):
- Women who are pregnant or breast feeding are not 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.
- Current major DSM-5 Axis 1 psychiatric diagnosis requiring medications that interfere with radiotracer binding, as identified during a 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
- Current severe substance use disorder (SUD), with heavy drug use in the past 3 months and a positive urine toxicology screen for that drug, other than OUD, and /or current treatment for an SUD other than OUD that would interfere with study procedures and outcome. In this group, this includes MAT for OUD.
- A breath alcohol concentration (BAC) reading > 0.01, a urine toxicology test positive for prohibited drugs.
- Current use or use within the past 12 months of any medications containing naltrexone or other MOR ligands (e.g., buprenorphine, methadone)
- Use within the month prior to screening of any antipsychotic, anticonvulsant, or stimulant medication or any other medication that is deemed by a physician investigator to potentially interfere with carfentanil binding at the MOR.
- 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.
- Cohort 3 (Healthy Controls):
- 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 use disorder (SUD) and /or current treatment for a SUD.
- 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 or a urine toxicology test positive for prohibited drugs.
- Current use or use within the past 12 months of any medications containing naltrexone or other MOR ligands (e.g., buprenorphine, methadone)
- Current use or use within the past 12 months of medications that could interfere with radiotracer binding. (Participants will be instructed to refrain from using any study-prohibited drugs, though participants will be allowed to take prescription medicines that are not exclusionary throughout their participation in the study.)
- 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, naloxone, or, if undergoing 3rd PET scan, loperamide.
- 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. This includes a history of colitis, by medical record review or self-report.
Trial locations and contacts
1 site in 1 country.
United States1 site
University of Pennsylvania, Perelman School of Medicine
Philadelphia, Pennsylvania, 19104
About this study
Official title: Pilot Study of a Multi-System Analysis of Opioid Receptor Binding
This study will enroll up to 60 adults (including 30 females and 30 males) in three cohorts of up to 20 subjects each. In all three groups, [11C]carfentanil whole-body PET imaging will be used to examine the central nervous system (CNS) and broader systemic opioid binding in an initial scan session. In the two groups not receiving standard of care medication assisted treatment (MAT) for opioid use disorder (OUD) the effects on [11C]carfentanil binding potential of the blockade of opioid binding by the non-selective opioid antagonist naloxone administered parenterally in a second scan session will also be examined. If two scans are completed they can be done on the same day or on different days.
Read the detailed description
This study will enroll up to 60 adults (including 30 females and 30 males) in three cohorts [Opioid Use Disorder (OUD) + medication-assisted treatment (MAT), OUD - MAT, or Healthy Controls] up to 20 subjects each. In all three groups, [11C]carfentanil whole-body PET imaging will be used to examine the central nervous system (CNS) and broader systemic opioid binding in an initial scan session. In the two groups not receiving standard of care medication assisted treatment (MAT) for opioid used disorder (OUD), the effects on [11C]carfentanil binding potential of the blockade of opioid binding by the non-selective opioid antagonist naloxone administered parenterally in a second scan session will also be examined. If two scans are completed they can be done on the same day or on different days.
Findings from this study will demonstrate the distribution of opioid effects in brain and other organs in healthy controls and individuals with opioid use disorder (OUD), including those treated with the opioid agonists buprenorphine or methadone. Thus, this project will inform clinically relevant questions related to OUD.
In all three groups we would also like to collect a blood sample to be used for future testing, including genome-wide micro-array testing that may be used for genome-wide association studies (GWAS). Approximately 13 mL of blood will be drawn and stored for future testing. This blood draw will occur once but could be done at any visit. Participants who have already completed the imaging study may be recontacted and reconsented to complete this blood draw, if they agree.
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 an initial [11C]carfentanil positron emission tomography/computed tomography (PET/CT) scan. Subjects not receiving MAT for OUD may undergo a second scan that includes pretreatment with parenteral naloxone. For subjects participating in the HC cohort who agree to undergo a 3rd PET scan, the scan may be done up to 2 years after their original PET scans. However, depending on the length of time since initial enrollment subjects may be undergo repeat screening or baseline assessments (including screening labs or psychological assessments) at the discretion of an investigator prior to undergoing the 3rd scan to confirm that no eligibility criteria have changed in the period since initial scanning. We will do an interval baseline/screening assessment in which we take a history and complete a physical exam informed by the prior history and physical, and update them. We will repeat labs and query concomitant meds (also as warranted by the history). We will not repeat cognitive testing. We will repeat the work-up with anyone whose prior assessment occurred longer than a 1 year from re-contact.
Analyses will compare the binding potential (BPND) in the brain and other body parts across the three cohorts (OUD+/MAT+, OUD+/MAT-, HC). In the two groups not receiving MAT (OUD+/MAT- and HC), binding potential and distribution will be compared between subjects by contrasting the [11C]carfentanil-only scan with the [11C]carfentanil scan preceded by naloxone treatment. 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. In the non-MAT groups, a dose of naloxone will be injected intravenously approximately 10-15 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 to measure radioactive counts and/or bio-metabolites. For participants in Cohort 1 who are on MAT an additional approximately 5 mL of blood will be drawn prior to injection of [11C]carfentanil to measure MAT levels.
HC subjects who undergo a 3rd scan, on the day of the scan, will be given an oral dose of loperamide hydrochloride (IMODIUM®) 45-75 minutes prior to the [11C]carfentanil injection and the start of the scan.
Subjects are required to have had a brain MRI performed within 1 year prior to study enrollment (subjects participating in the HC cohort and undergoing a 3rd scan will not have to repeat the MRI if they previously completed an MRI), or if the subject has not had a brain MRI deemed acceptable for use for this study, they will be asked to undergo a research brain MRI after they have consented for this study.
- Conditions
- Healthy, Opioid Use Disorder
- Being tested
- Carfentanil, C-11, Naloxone, Loperamide Hydrochloride
- Keywords
- Medication Assisted Treatment, Buprenorphine, Naloxone
- Medical subject headings
- Opioid-Related Disorders
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Carfentanil, C-11Drug
Also called [11C]Carfentanil
Investigational radiotracer to be injected by IV as s a bolus during both study PET/CT scans.
NaloxoneDrug
Non-selective opioid antagonist injected by IV parenterally during the second study PET/CT scan only.
Loperamide HydrochlorideDrug
Also called Imodium
Loperamide is an FDA- approved, over-the-counter drug for the control and symptomatic relief of acute or chronic diarrhea given orally prior to the optional HC third PET/CT scan only.
| Study group | Role | What they receive |
|---|---|---|
| Opioid Use Disorder and Medication Assisted Treatment (OUD+/MAT-) | Experimental | Study imaging will be performed using a whole-body PET/CT scanner.
Each participant will receive ≤ 10 mCi of [11C]carfentanil intravenously (approximate range for most studies is anticipated to be 2-10 mCi ).
Participants will undergo dynamic PET/CT imaging of the brain and body. The scan will take approximately 90 minutes for each scan session. Study imaging will be performed using a whole-body PET/CT scanner.
For the first study scan, participants will receive [11C]carfentanil radiotracer alone. For the second study scan approximately 13 mcg/kg of naloxone will be administered by IV prior to the [11C]carfentanil injection. If both scans are done the same day, then the naloxone injection will be given before the second scan session and there will be a break between the two scan sessions of approximately 3 hours. Receives: Drug: Carfentanil, C-11; Drug: Naloxone |
| Opioid Use Disorder Only (OUD+/MAT-) | Experimental | Study imaging will be performed using a whole-body PET/CT scanner.
Each participant will receive ≤ 10 mCi of [11C]carfentanil intravenously (approximate range for most studies is anticipated to be 2-10 mCi ).
Participants will undergo dynamic PET/CT imaging of the brain and body. The scan will take approximately 90 minutes for each scan session. Study imaging will be performed using a whole-body PET/CT scanner.
For the first study scan, participants will receive [11C]carfentanil radiotracer alone. For the second study scan approximately 13 mcg/kg of naloxone will be administered by IV prior to the [11C]carfentanil injection. If both scans are done the same day, then the naloxone injection will be given before the second scan session and there will be a break between the two scan sessions of approximately 3 hours. Receives: Drug: Carfentanil, C-11; Drug: Naloxone |
| Healthy Controls (OUD-) | Experimental | Study imaging will be performed using a whole-body PET/CT scanner.
Each participant will receive ≤ 10 mCi of [11C]carfentanil intravenously (approximate range for most studies is anticipated to be 2-10 mCi ).
Participants will undergo dynamic PET/CT imaging of the brain and body. The scan will take approximately 90 minutes for each scan session. Study imaging will be performed using a whole-body PET/CT scanner.
For the 1st study scan, participants will receive [11C]carfentanil radiotracer alone. For the 2nd study scan approximately 13 mcg/kg of naloxone will be administered by IV prior to the [11C]carfentanil injection. If both scans are done the same day, then the naloxone injection will be given before the 2nd scan and there will be a break between the two scans of approximately 3 hours. For the optional 3rd study scan 4 mg capsule or 30 mL solution standard adult dose of loperamide hydrochloride will be given orally 45-75 minutes prior to the[11C]carfentanil injection. Receives: Drug: Carfentanil, C-11; Drug: Naloxone; Drug: Loperamide Hydrochloride |
What is being measured
The primary outcome is the main question the study is designed to answer.
MOR BPND measurement - [11C]carfentanil
Measure MOR BPND following the administration of [11C]carfentanil alone in 5 brain regions of interest (ROIs) relevant to addiction (the subgenual anterior cingulate, ventral pallidum, amygdala, nucleus accumbens, and dorsal striatum), spinal cord (key role in transmitting pain signals) and organs outside the central nervous system (CNS) that contain mu-opioid receptors (e.g., the gastrointestinal tract, heart).
Measured: Baseline
MOR BPND measurement - naloxone and [11C]carfentanil
Measure MOR BPND following the administration of both naloxone and [11C]carfentanil in 5 brain regions of interest (ROIs) relevant to addiction (the subgenual anterior cingulate, ventral pallidum, amygdala, nucleus accumbens, and dorsal striatum), spinal cord (key role in transmitting pain signals) and organs outside the central nervous system (CNS) that contain mu-opioid receptors (e.g., the gastrointestinal tract, heart).
Measured: Follow up - 1 day to 6 weeks
Secondary outcomes (1)
MOR BPND measurement - loperamide and [11C]carfentanil
Measure MOR BPND following the administration of both oral loperamide hydrochloride (pre-injection) and [11C]carfentanil to help develop imaging methods to characterize differential mu-opioid receptor availability in the brain and gut.
Measured: Follow up - 1 day to 6 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Sep 2022
- Study start20 Sep 2022
- Primary completionSep 2027 (estimated)
- Study completionSep 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for HealthyStudies of the same condition, open and under way.
- More trials run by University of PennsylvaniaThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 1
- Primary purpose
- Other
- Allocation
- Non-randomised
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 25 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Pennsylvania
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05528848
- Sponsor's protocol ID
- 851051
- Status last verified
- Mar 2026
- First submitted
- 1 Sep 2022
- Last updated
- 30 Mar 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Publications
Dubroff JG, Hsieh CJ, Wiers CE, Lee H, Schmitz A, Li EJ, Schubert EK, Mach RH, Kranzler HR. [11C]Carfentanil PET Whole-Body Imaging of mu-Opioid Receptors: A First in-Human Study. J Nucl Med. 2025 Jul 1;66(7):1112-1118. doi: 10.2967/jnumed.124.269413.
PubMed 40341091
Study at a glance
From the registry record, last updated by the sponsor on 30 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Pilot Study of a Multi-System Analysis of Opioid Receptor Binding
- ClinicalTrials.gov ID
- NCT05528848
- Acronym / sponsor ID
- 851051
- Conditions
- Healthy, Opioid Use Disorder
- Keywords
- Medication Assisted Treatment, Buprenorphine, Naloxone
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 25 participants (actual)
- Lead sponsor
- University of PennsylvaniaUniversity, hospital or other
- Study start
- 20 Sep 2022 (actual)
- Primary completion
- Sep 2027 (estimated)
- Study completion
- Sep 2027 (estimated)
- First posted
- 6 Sep 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study will enroll up to 60 adults (including 30 females and 30 males) in three cohorts of up to 20 subjects each. In all three groups, [11C]carfentanil whole-body PET imaging will be used to examine the central nervous system (CNS) and broader systemic opioid binding in an initial scan session. In the two groups not receiving standard of care medication assisted treatment (MAT) for opioid use disorder (OUD) the effects on [11C]carfentanil binding potential of the blockade of opioid binding by the non-selective opioid antagonist naloxone administered parenterally in a second scan session will also be examined. If two scans are completed they can be done on the same day or on different days.
Detailed description
This study will enroll up to 60 adults (including 30 females and 30 males) in three cohorts [Opioid Use Disorder (OUD) + medication-assisted treatment (MAT), OUD - MAT, or Healthy Controls] up to 20 subjects each. In all three groups, [11C]carfentanil whole-body PET imaging will be used to examine the central nervous system (CNS) and broader systemic opioid binding in an initial scan session. In the two groups not receiving standard of care medication assisted treatment (MAT) for opioid used disorder (OUD), the effects on [11C]carfentanil binding potential of the blockade of opioid binding by the non-selective opioid antagonist naloxone administered parenterally in a second scan session will also be examined. If two scans are completed they can be done on the same day or on different days.
Findings from this study will demonstrate the distribution of opioid effects in brain and other organs in healthy controls and individuals with opioid use disorder (OUD), including those treated with the opioid agonists buprenorphine or methadone. Thus, this project will inform clinically relevant questions related to OUD.
In all three groups we would also like to collect a blood sample to be used for future testing, including genome-wide micro-array testing that may be used for genome-wide association studies (GWAS). Approximately 13 mL of blood will be drawn and stored for future testing. This blood draw will occur once but could be done at any visit. Participants who have already completed the imaging study may be recontacted and reconsented to complete this blood draw, if they agree.
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 an initial [11C]carfentanil positron emission tomography/computed tomography (PET/CT) scan. Subjects not receiving MAT for OUD may undergo a second scan that includes pretreatment with parenteral naloxone. For subjects participating in the HC cohort who agree to undergo a 3rd PET scan, the scan may be done up to 2 years after their original PET scans. However, depending on the length of time since initial enrollment subjects may be undergo repeat screening or baseline assessments (including screening labs or psychological assessments) at the discretion of an investigator prior to undergoing the 3rd scan to confirm that no eligibility criteria have changed in the period since initial scanning. We will do an interval baseline/screening assessment in which we take a history and complete a physical exam informed by the prior history and physical, and update them. We will repeat labs and query concomitant meds (also as warranted by the history). We will not repeat cognitive testing. We will repeat the work-up with anyone whose prior assessment occurred longer than a 1 year from re-contact.
Analyses will compare the binding potential (BPND) in the brain and other body parts across the three cohorts (OUD+/MAT+, OUD+/MAT-, HC). In the two groups not receiving MAT (OUD+/MAT- and HC), binding potential and distribution will be compared between subjects by contrasting the [11C]carfentanil-only scan with the [11C]carfentanil scan preceded by naloxone treatment. 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. In the non-MAT groups, a dose of naloxone will be injected intravenously approximately 10-15 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 to measure radioactive counts and/or bio-metabolites. For participants in Cohort 1 who are on MAT an additional approximately 5 mL of blood will be drawn prior to injection of [11C]carfentanil to measure MAT levels.
HC subjects who undergo a 3rd scan, on the day of the scan, will be given an oral dose of loperamide hydrochloride (IMODIUM®) 45-75 minutes prior to the [11C]carfentanil injection and the start of the scan.
Subjects are required to have had a brain MRI performed within 1 year prior to study enrollment (subjects participating in the HC cohort and undergoing a 3rd scan will not have to repeat the MRI if they previously completed an MRI), or if the subject has not had a brain MRI deemed acceptable for use for this study, they will be asked to undergo a research brain MRI after they have consented for this study.
Study design
- Primary purpose
- Other
- Allocation
- Non-randomised
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| Opioid Use Disorder and Medication Assisted Treatment (OUD+/MAT-) | Experimental | Drug: Carfentanil, C-11, Drug: NaloxoneStudy imaging will be performed using a whole-body PET/CT scanner. Each participant will receive ≤ 10 mCi of [11C]carfentanil intravenously (approximate range for most studies is anticipated to be 2-10 mCi ). Participants will undergo dynamic PET/CT imaging of the brain and body. The scan will take approximately 90 minutes for each scan session. Study imaging will be performed using a whole-body PET/CT scanner. For the first study scan, participants will receive [11C]carfentanil radiotracer alone. For the second study scan approximately 13 mcg/kg of naloxone will be administered by IV prior to the [11C]carfentanil injection. If both scans are done the same day, then the naloxone injection will be given before the second scan session and there will be a break between the two scan sessions of approximately 3 hours. |
| Opioid Use Disorder Only (OUD+/MAT-) | Experimental | Drug: Carfentanil, C-11, Drug: NaloxoneStudy imaging will be performed using a whole-body PET/CT scanner. Each participant will receive ≤ 10 mCi of [11C]carfentanil intravenously (approximate range for most studies is anticipated to be 2-10 mCi ). Participants will undergo dynamic PET/CT imaging of the brain and body. The scan will take approximately 90 minutes for each scan session. Study imaging will be performed using a whole-body PET/CT scanner. For the first study scan, participants will receive [11C]carfentanil radiotracer alone. For the second study scan approximately 13 mcg/kg of naloxone will be administered by IV prior to the [11C]carfentanil injection. If both scans are done the same day, then the naloxone injection will be given before the second scan session and there will be a break between the two scan sessions of approximately 3 hours. |
| Healthy Controls (OUD-) | Experimental | Drug: Carfentanil, C-11, Drug: Naloxone, Drug: Loperamide HydrochlorideStudy imaging will be performed using a whole-body PET/CT scanner. Each participant will receive ≤ 10 mCi of [11C]carfentanil intravenously (approximate range for most studies is anticipated to be 2-10 mCi ). Participants will undergo dynamic PET/CT imaging of the brain and body. The scan will take approximately 90 minutes for each scan session. Study imaging will be performed using a whole-body PET/CT scanner. For the 1st study scan, participants will receive [11C]carfentanil radiotracer alone. For the 2nd study scan approximately 13 mcg/kg of naloxone will be administered by IV prior to the [11C]carfentanil injection. If both scans are done the same day, then the naloxone injection will be given before the 2nd scan and there will be a break between the two scans of approximately 3 hours. For the optional 3rd study scan 4 mg capsule or 30 mL solution standard adult dose of loperamide hydrochloride will be given orally 45-75 minutes prior to the[11C]carfentanil injection. |
Who may qualify
- Ages
- 18 to 50 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (15 listed)
- 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.
- OUD positive (+): Participants will meet DSM-5 criteria for a lifetime diagnosis of OUD and will be on a stable dosage of buprenorphine or methadone treatment for at least four weeks prior to the screening visit.
- 18-50 years of age
Key exclusion criteria (40 listed)
- 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.
- Current major DSM-5 Axis 1 psychiatric diagnosis that requires treatment with a medication that interferes with opioid receptor binding, 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Carfentanil, C-11Also: [11C]CarfentanilInvestigational radiotracer to be injected by IV as s a bolus during both study PET/CT scans. | Drug | Healthy Controls (OUD-), Opioid Use Disorder Only (OUD+/MAT-), Opioid Use Disorder and Medication Assisted Treatment (OUD+/MAT-) |
| NaloxoneNon-selective opioid antagonist injected by IV parenterally during the second study PET/CT scan only. | Drug | Healthy Controls (OUD-), Opioid Use Disorder Only (OUD+/MAT-), Opioid Use Disorder and Medication Assisted Treatment (OUD+/MAT-) |
| Loperamide HydrochlorideAlso: ImodiumLoperamide is an FDA- approved, over-the-counter drug for the control and symptomatic relief of acute or chronic diarrhea given orally prior to the optional HC third PET/CT scan only. | Drug | Healthy Controls (OUD-) |
Primary outcome
MOR BPND measurement - [11C]carfentanil
Time frame: Baseline
Measure MOR BPND following the administration of [11C]carfentanil alone in 5 brain regions of interest (ROIs) relevant to addiction (the subgenual anterior cingulate, ventral pallidum, amygdala, nucleus accumbens, and dorsal striatum), spinal cord (key role in transmitting pain signals) and organs outside the central nervous system (CNS) that contain mu-opioid receptors (e.g., the gastrointestinal tract, heart).
MOR BPND measurement - naloxone and [11C]carfentanil
Time frame: Follow up - 1 day to 6 weeks
Measure MOR BPND following the administration of both naloxone and [11C]carfentanil in 5 brain regions of interest (ROIs) relevant to addiction (the subgenual anterior cingulate, ventral pallidum, amygdala, nucleus accumbens, and dorsal striatum), spinal cord (key role in transmitting pain signals) and organs outside the central nervous system (CNS) that contain mu-opioid receptors (e.g., the gastrointestinal tract, heart).
1 secondary outcome
MOR BPND measurement - loperamide and [11C]carfentanil
Time frame: Follow up - 1 day to 6 weeks
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 30 Mar 2026.
- Derived from this study: PubMed 40341091Dubroff JG, Hsieh CJ, Wiers CE, Lee H, Schmitz A, Li EJ, Schubert EK, Mach RH, Kranzler HR. [11C]Carfentanil PET Whole-Body Imaging of mu-Opioid Receptors: A First in-Human Study. J Nucl Med. 2025 Jul 1;66(7):1112-1118. doi: 10.2967/jnumed.124.269413.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1 study testing Carfentanil, C-11, Naloxone and Loperamide Hydrochloride in people with Healthy and Opioid Use Disorder, run by University of Pennsylvania at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 15 inclusion and 40 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 30 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
MOR BPND measurement - [11C]carfentanil (time frame: Baseline). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05528848, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 30 Mar 2026.