Opioid Use DisorderPhase 1NCT06261905

Vitamin D in OUD: Exploration of Alterations on the Dopamine D2/D3 Receptor System

A Phase 1 study testing [11C]-PHNO, Calcitriol and PET Scan in people with Opioid Use Disorder, run by Yale University at 1 site in United States.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record

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Trial summary

Who is it for?: Ages 18 to 50 yearsHealthy volunteers can take part
Conditions the study is for: Opioid Use Disorder
What is being tested?: [11C]-PHNO, Calcitriol and PET Scan
Type of treatment: Pill or oral medicine, Injection or infusion, Surgery or procedure
Could I receive a placebo?: Yes, some participants may receive a placebo
How many people: 5 participants
Where: 1 siteUnited States
Study dates: 13 Mar 2024to 18 Feb 2025
Phase: Phase 1
Are there results?: None posted in the registry

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

Age 18-50 years
Voluntary, written, informed consent
Physically healthy by medical history, physical, neurological, ECG, and laboratory examinations
Meets the criteria for OUD, as determined by the Structured Clinical Interview for DSM-5 (SCID)
Stable and receiving buprenorphine treatment for OUD
For females, non-lactating, with a negative serum or urine pregnancy (hCG) test
Lab results without clinically relevant findings (e.g., renal function, electrolytes, and vitamin D levels)
English speaking

Who cannot join

Medical contraindication to calcitriol administration (e.g., history of hypersensitivity to calcitriol or any component of the formulation, hypercalcemia or vitamin D toxicity)
History of substance dependence (e.g., alcohol, sedative hypnotics), except for nicotine and opiates.
A primary major DSM-5 psychiatric disorder (e.g., schizophrenia, bipolar disorder, major depression, etc.) as determined by the SCID, except for Opioid Use Disorder and related conditions.
A history of significant medical (e.g., cardiovascular, diabetic/metabolic) or neurological (e.g., cerebrovascular accidents, seizure, traumatic brain injury) illness
Positive answers on the cardiac history questionnaire that may place the subject at higher risk, as determined by the study physician's review of both the questionnaire responses and screening ECG. If there is concern for the subject's safety due to these assessments, research staff will consult a Yale PET Center affiliated cardiologist prior to including the subject for the study.
Current use of psychotropic and/or potentially psychoactive prescription medications

Show all 25Show fewer

Receiving medications for OUD other than buprenorphine (e.g., methadone treatment)
For females, laboratory (β-HCG) or physical evidence of pregnancy/lactation
MRI-incompatible implants and other contraindications for MRI (i.e., aneurysm clip, metal fragments, internal electrical devices such as a cochlear implant, spinal cord stimulator or pacemaker)
History of claustrophobia or feeling of inability to lie still on his/her back for the PET or MRI scans
History of any bleeding disorder or current anticoagulant therapy
Donation or loss of 550 mL of blood or more (including plasmapheresis) or receipt of a transfusion of any blood product within 8 weeks prior to the first test day.
Use of any prescription medications and/or over-the-counter medications, vitamins and/or herbal supplements which could have a negative clinical interaction with calcitriol or which could confound scientific results of the study, within 2 weeks prior to each test day (e.g., thiazide diuretics, Mg based antiacids, digoxin, etc,).
Serum levels of 25(OH)D3 below 12 ng/ml.
Morbid obesity i.e., BMI over 35 (more prone to lower vitamin D levels)
Subjects with history of prior radiation exposure for research purposes within the past year such that participation in this study would place them over FDA limits for annual radiation exposure. This guideline is an effective dose of 5 rem received per year.
Subjects with current, past or anticipated exposure to radiation in the workplace
History of kidney stones within the past 5 years
Any degree of renal failure
History of parathyroid disorder (hyper or hypoparathyroidism)
History of osteoporosis or any pathologic fractures
Vitamin D supplementation in any form in the past 3 months
Known hypersensitivity to [11C]-PHNO or calcitriol
Malabsorption syndromes (i.e., Celiac sprue)
Serum corrected calcium > 10.5 mg/dl or phosphate > 4.2 mg/dL

Trial locations and contacts

1 site in 1 country.

United States1 site

Yale School of Medicine
New Haven, Connecticut, 06510

Other trials in United States

About this study

Official title: Exploration of Baseline Alterations on the Dopamine D2/D3 Receptor System and the Effects of Vitamin D in Opioid Use Disorder: an [11C]-PHNO Study

The research team is investigating Opioid Use Disorder (OUD), a disorder characterized by dysregulated dopaminergic tone, to evaluate the mechanisms of adjunctive treatment with calcitriol. The investigators will recruit 12 subjects with OUD and 12 healthy subjects to participate in a double-blind, randomized study design where subjects will complete up to 2 Positron Emission Tomography (PET) scans using [11C]-PHNO. The investigators will compare subjects in differences between their own study days and in differences between healthy control subjects and subjects with OUD.

Read the detailed description

Previous research has indicated that Dopamine (DA) may play a role in withdrawal and dependence in Opioid Use Disorder (OUD). The present study will investigate dopamine receptor availability in 12 subjects with OUD compared with 12 HC subjects using [11C](+)-PHNO and the impact of calcitriol on these receptors.

Research has indicated that a common feature in substance use disorders (SUD) is a hypo-dopaminergic state. Further, preclinical and observational research has pointed to a possible benefit of calcitriol in individuals who have OUD and our research group has previously shown the potential benefits of calcitriol on addressing this hypo-dopaminergic state. If successful, the results of this research study may improve the standard treatment for OUD through calcitriol supplementation.

Specifically, the present study seeks to address the following aims:

Specific Aim 1: As part of a between-subject study design, to determine whether acute calcitriol (vs. placebo) administration is associated with greater dopamine (DA) release in the caudate, putamen, ventral striatum (VST), and substantia nigra / ventral tegmental area (SN/VTA) of subjects with OUD compared to healthy control subjects (HCs).

Specific Aim 2: As part of a within-subject, two-day study design, to determine whether acute calcitriol (vs. placebo) administration is associated with greater dopamine (DA) release in the caudate, putamen, ventral striatum (VST), and substantia nigra / ventral tegmental area (SN/VTA) of subjects with OUD.

Specific Aim 3: To determine whether acute calcitriol (vs. placebo) administration is associated with higher spontaneous eyeblink rate, a non-PET indicator of higher dopamine activity, among subjects with OUD.

Specific Aim 4: To determine whether acute calcitriol (vs. placebo) administration is associated with better performance on neurocognitive measures (e.g., the Continuous Performance Task or CPT-IP and the Probabilistic Reversal Learning Task or PRLT) among subjects with OUD.

Conditions: Opioid Use Disorder
Being tested: [11C]-PHNO, Calcitriol, Placebo Control, PET Scan
Keywords: Vitamin D
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.

[11C]-PHNODrug
Also called PHNO
PHNO is used as a tracer for in-vivo imaging.
CalcitriolDietary supplement
Also called Vitamin D
Calcitriol is an active form of Vitamin D and is given in 3 0.5mcg capsules per dose.
Placebo ControlOther
A placebo is an inert capsule, which contains no active ingredients. The placebo will be given in 3 0.5mcg capsules per dose.
PET ScanProcedure or surgery
A high resolution PET Scan performed using a NeurExplorer CT scanner.

Study groups in NCT06261905
Study group	Role	What they receive
Calcitriol	Active comparator	Subjects with OUD will receive a baseline MRI. On the night before and day of testing, subjects with OUD will receive two doses of calcitriol (3.0mcg total), followed by PHNO injection and PET Scan for the calcitriol condition. All subjects will complete the study with both active calcitriol and a placebo control and the order these interventions are received will be randomized. Receives: Drug: [11C]-PHNO; Dietary Supplement: Calcitriol; Procedure: PET Scan
Placebo	Placebo comparator	Subjects with OUD will receive a baseline MRI. On the night before and day of testing, subjects with OUD will receive two doses of an inactive placebo, followed by PHNO injection and PET Scan for the placebo condition. All subjects will complete the study with both active calcitriol and a placebo control and the order these interventions are received will be randomized. Receives: Drug: [11C]-PHNO; Other: Placebo Control; Procedure: PET Scan

What is being measured

The primary outcome is the main question the study is designed to answer.

Non-displaceable Tracer Binding Potentials (BPND)
BPND is a metric that assesses the level of dopamine activity in a priori regions of interest. For Specific Aim 1, the investigators plan to assess the differences in baseline BPND in dopamine D2/D3 receptors between healthy control subjects and the baseline placebo-controlled scan for subjects with OUD.
Measured: One 120-minute scan.
Non-displaceable Tracer Binding Potentials (BPND)
BPND is a metric that assesses the level of dopamine activity in a priori regions of interest. For Specific Aim 2, the investigators plan to assess the differences in BPND in dopamine D2/D3 receptors within subjects who have OUD. The investigators will compare BPND on the placebo-controlled experimental day and BPND on the active calcitriol experimental day.
Measured: Two 120-minute scans, at least 6 days apart between study conditions.

Secondary outcomes (3)

Spontaneous Blink Rate (SBR)
SBR is a metric that may assess levels of dopamine activity, without requiring the subject to undergo a PET scan. Subjects will be recorded for approximately 5 minutes to assess blink rate during each experimental day to address Specific Aim 3.
Measured: Two 5-minute tasks, at least 6 days apart between study conditions.
Continuous Performance Task - Identical Pairs (CPT-IP)
The CPT-IP is a computer based test where subjects are shown a random sequence of numbers (2-digit, 3-digit, and 4-digit) and are instructed to press a button as quickly and accurately as possible with their preferred hand when a number repeats. Subjects are instructed to withhold their response for any other sequence of numbers. Subjects will complete this task on each experimental day to address Specific Aim 4.
Measured: Two 10-minute tasks, at least 6 days apart between study conditions.
Probabilistic Reversal Learning Task (PRLT)
The PRLT is a computer based test where subjects are instructed to select a card from three randomly sorted piles and are asked to try to maximize their score in the task. Subjects will complete this task on each experimental day to address Specific Aim 4.
Measured: Two 10-minute tasks, at least 6 days apart between study conditions.

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

13 Mar 202418 Feb 2025

First posted15 Feb 2024
Study start13 Mar 2024
Primary completion18 Feb 2025
Study completion18 Feb 2025

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Other trials for Opioid Use DisorderStudies of the same condition, open and under way.
More trials run by Yale UniversityThe 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: Treatment
Allocation: Randomised
Intervention model: Crossover
Model description: This is primarily a within-subject, two scan, randomized, double-blind, placebo-controlled study design. Healthy control subjects will only complete one scan to serve as a baseline comparison for subjects with OUD.
Masking: Double blind
Who is masked: Participant, Investigator
Enrolment: 5 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT06261905
Sponsor's protocol ID: 2000036908
Other IDs: 000
Status last verified: Nov 2025
First submitted: 7 Feb 2024
Last updated: 14 Nov 2025
Results posted: No
Data monitoring committee: No
FDA-regulated drug: Yes
FDA-regulated device: No

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

See locations

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All Opioid Use Disorder trials

Study at a glance

From the registry record, last updated by the sponsor on 14 Nov 2025. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: Exploration of Baseline Alterations on the Dopamine D2/D3 Receptor System and the Effects of Vitamin D in Opioid Use Disorder: an [11C]-PHNO Study
ClinicalTrials.gov ID: NCT06261905
Acronym / sponsor ID: 2000036908
Conditions: Opioid Use Disorder
Keywords: Vitamin D
Phase: Phase 1
Study type: Interventional
Recruitment status: Completed
Enrolment: 5 participants (actual)
Lead sponsor: Yale UniversityUniversity, hospital or other
Collaborators: University of Pennsylvania
Study start: 13 Mar 2024 (actual)
Primary completion: 18 Feb 2025 (actual)
Study completion: 18 Feb 2025 (actual)
First posted: 15 Feb 2024 (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.

Detailed description

Specifically, the present study seeks to address the following aims:

Study design

Primary purpose: Treatment
Allocation: Randomised
Intervention model: Crossover
Masking: Double blind (participant, investigator)
Number of arms: 2
Model description: This is primarily a within-subject, two scan, randomized, double-blind, placebo-controlled study design. Healthy control subjects will only complete one scan to serve as a baseline comparison for subjects with OUD.

Arm	Type	Receives
Calcitriol	Active comparator	Drug: [11C]-PHNO, Dietary Supplement: Calcitriol, Procedure: PET ScanSubjects with OUD will receive a baseline MRI. On the night before and day of testing, subjects with OUD will receive two doses of calcitriol (3.0mcg total), followed by PHNO injection and PET Scan for the calcitriol condition. All subjects will complete the study with both active calcitriol and a placebo control and the order these interventions are received will be randomized.
Placebo	Placebo comparator	Drug: [11C]-PHNO, Other: Placebo Control, Procedure: PET ScanSubjects with OUD will receive a baseline MRI. On the night before and day of testing, subjects with OUD will receive two doses of an inactive placebo, followed by PHNO injection and PET Scan for the placebo condition. All subjects will complete the study with both active calcitriol and a placebo control and the order these interventions are received will be randomized.

Who may qualify

Ages: 18 to 50 years
Sex: All
Healthy volunteers: Accepted
Age groups: Adult

Key inclusion criteria (8 listed)

Age 18-50 years
Voluntary, written, informed consent
Physically healthy by medical history, physical, neurological, ECG, and laboratory examinations
Meets the criteria for OUD, as determined by the Structured Clinical Interview for DSM-5 (SCID)
Stable and receiving buprenorphine treatment for OUD

Key exclusion criteria (25 listed)

Medical contraindication to calcitriol administration (e.g., history of hypersensitivity to calcitriol or any component of the formulation, hypercalcemia or vitamin D toxicity)
History of substance dependence (e.g., alcohol, sedative hypnotics), except for nicotine and opiates.
A primary major DSM-5 psychiatric disorder (e.g., schizophrenia, bipolar disorder, major depression, etc.) as determined by the SCID, except for Opioid Use Disorder and related conditions.
A history of significant medical (e.g., cardiovascular, diabetic/metabolic) or neurological (e.g., cerebrovascular accidents, seizure, traumatic brain injury) illness
Positive answers on the cardiac history questionnaire that may place the subject at higher risk, as determined by the study physician's review of both the questionnaire responses and screening ECG. If there is concern for the subject's safety due to these assessments, research staff will consult a Yale PET Center affiliated cardiologist prior to including the subject for the study.

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
[11C]-PHNOAlso: PHNOPHNO is used as a tracer for in-vivo imaging.	Drug	Calcitriol, Placebo
CalcitriolAlso: Vitamin DCalcitriol is an active form of Vitamin D and is given in 3 0.5mcg capsules per dose.	Dietary supplement	Calcitriol
Placebo ControlA placebo is an inert capsule, which contains no active ingredients. The placebo will be given in 3 0.5mcg capsules per dose.	Other	Placebo
PET ScanA high resolution PET Scan performed using a NeurExplorer CT scanner.	Procedure or surgery	Calcitriol, Placebo

Primary outcome

Non-displaceable Tracer Binding Potentials (BPND)
Time frame: One 120-minute scan.
BPND is a metric that assesses the level of dopamine activity in a priori regions of interest. For Specific Aim 1, the investigators plan to assess the differences in baseline BPND in dopamine D2/D3 receptors between healthy control subjects and the baseline placebo-controlled scan for subjects with OUD.
Non-displaceable Tracer Binding Potentials (BPND)
Time frame: Two 120-minute scans, at least 6 days apart between study conditions.
BPND is a metric that assesses the level of dopamine activity in a priori regions of interest. For Specific Aim 2, the investigators plan to assess the differences in BPND in dopamine D2/D3 receptors within subjects who have OUD. The investigators will compare BPND on the placebo-controlled experimental day and BPND on the active calcitriol experimental day.

3 secondary outcomes

Spontaneous Blink Rate (SBR)
Time frame: Two 5-minute tasks, at least 6 days apart between study conditions.
Continuous Performance Task - Identical Pairs (CPT-IP)
Time frame: Two 10-minute tasks, at least 6 days apart between study conditions.
Probabilistic Reversal Learning Task (PRLT)
Time frame: Two 10-minute tasks, at least 6 days apart between study conditions.

Results and safety

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 14 Nov 2025.

Related trials for Opioid Use Disorder

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People Who Use Opioids/People With Opioid Use Disorder (OUD)
Enrolling by invitationObservational study
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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.

Marc Potenza, MD, PhD principal investigator

Yale University

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 [11C]-PHNO, Calcitriol and PET Scan in people with Opioid Use Disorder, run by Yale University 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 8 inclusion and 25 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: finished, as of the sponsor's last update on 14 Nov 2025. 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. Some participants in this study may receive a placebo. 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?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

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?

Non-displaceable Tracer Binding Potentials (BPND) (time frame: One 120-minute scan.). 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 NCT06261905.

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 14 Nov 2025.