Major Depressive DisorderPhase 1NCT04981561

Safety and Tolerability of Zelquistinel in Normal Human Volunteers

A Phase 1 study testing zelquistinel in people with Major Depressive Disorder, run by Syndeio Biosciences, Inc.

Completed

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

Trial summary

To evaluate the safety and tolerability of single ascending doses of zelquistinel in normal human volunteers Read more about this study

Who is it for?: Ages 18 to 45 yearsHealthy volunteers can take part
Conditions the study is for: Major Depressive Disorder
What is being tested?: zelquistinel
Type of treatment: Pill or oral medicine
Could I receive a placebo?: Yes, some participants may receive a placebo
How many people: 68 participants
Where: No sites listed yet
Study dates: 9 Dec 2016to 21 Dec 2017
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 45 years
All sexes
Healthy volunteers accepted
Adult

Who may be able to join

Agree to effective method of birth control
If female, negative pregnancy test at screening and Day -1
Nonsmoking at least 2 years
BMI 18-30
Supine pulse rate 30-100

Who cannot join

Known hypersensitivity to NMDA receptor drugs
clinically significant disease in any body system
QTcF > 430 ms in males, >450 ms in females
positive test for hepatitis B or C
abnormal liver function tests on Day -1
History of alcohol or other substance abuse during the previous 5 years
Positive drug screen at screening or Day -1
Taken any medication within the past 14 days

About this study

Official title: A Phase 1, Single Ascending Dose Study to Evaluate the Safety, Tolerability, and Pharmacokinetics of AGN-241751 After Oral Administration in Healthy Volunteers

To evaluate the safety and tolerability of single ascending doses of zelquistinel in normal human volunteers

Read the detailed description

Single ascending dose (SAD), double-blind placebo-controlled study in normal human volunteers.

Secondary objectives:

To evaluate the pharmacokinetics (PK) and eeg biomarker of target engagement of zelquistinel following increasing single doses of zelquistinel.

Zelquistinel or Placebo: Dose/Mode of Administration: Single dose; oral

Conditions: Major Depressive Disorder
Being tested: zelquistinel, Placebo
Keywords: NMDA receptor, NMDA receptor positive allosteric modulator, pharmacokinetics, biomarker, eeg
Medical subject headings: Depressive Disorder, Major

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

zelquistinelDrug
Single dose of zelquistinel
PlaceboDrug
Placebo

Study groups in NCT04981561
Study group	Role	What they receive
100 microgram zelquistinel	Experimental	zelquistinel, 100 microgram tablet, PO, Single Dose with 28 day follow up Receives: Drug: zelquistinel
1 mg zelquistinel	Experimental	zelquistinel, 1 mg tablet, PO, Single Dose with 28 day follow up Receives: Drug: zelquistinel
3 mg zelquistinel	Experimental	zelquistinel, 3 mg tablet, PO, Single Dose with 28 day follow up Receives: Drug: zelquistinel
10 mg zelquistinel	Experimental	zelquistinel, 10 mg tablet, PO, Single Dose with 28 day follow up Receives: Drug: zelquistinel
25 mg zelquistinel	Experimental	zelquistinel, 25 mg tablet, PO, Single Dose with 28 day follow up Receives: Drug: zelquistinel
50 mg zelquistinel	Experimental	zelquistinel, 50 mg tablet, PO, Single Dose with 28 day follow up Receives: Drug: zelquistinel
100 mg zelquistinel	Experimental	zelquistinel, 100 mg tablet, PO, Single Dose with 28 day follow up Receives: Drug: zelquistinel
1 mg zelquistinel with CSF collection	Experimental	zelquistinel, 1 mg tablet, PO, Single Dose with 28 day follow up, with CSF collection Receives: Drug: zelquistinel
10 mg zelquistinel with CSF collection	Experimental	zelquistinel, 10 mg tablet, PO, Single Dose with 28 day follow up, with CSF collection Receives: Drug: zelquistinel
Placebo	Placebo comparator	Placebo tablet, PO, Single Dose with 28 day follow up Receives: Drug: Placebo

What is being measured

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

Treatment emergent adverse events
through study completion
Measured: 28 days

Secondary outcomes (3)

Pharmacokinetics, maximum plasma concentration
maximum plasma concentration
Measured: 24 hours
Pharmacokinetics, time to maximum plasma concentration
time to maximum plasma concentration
Measured: 24 hours
Pharmacokinetics, area under the curve for plasma concentration
area under the curve, plasma calculated 0-infinity
Measured: 72 hours

Timeline

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

9 Dec 201621 Dec 2017

First posted29 Jul 2021
Study start9 Dec 2016
Primary completion21 Dec 2017
Study completion21 Dec 2017

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Other trials for Major Depressive DisorderStudies of the same condition, open and under way.
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: Parallel groups
Model description: Double blind placebo controlled
Masking: Triple blind
Who is masked: Participant, Investigator, Outcomes assessor
Enrolment: 68 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT04981561
Sponsor's protocol ID: 3125-101-009
Status last verified: Jul 2021
First submitted: 18 Jul 2021
Last updated: 12 Mar 2026
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?

Official record

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All Major Depressive Disorder trials

Study at a glance

From the registry record, last updated by the sponsor on 12 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: A Phase 1, Single Ascending Dose Study to Evaluate the Safety, Tolerability, and Pharmacokinetics of AGN-241751 After Oral Administration in Healthy Volunteers
ClinicalTrials.gov ID: NCT04981561
Acronym / sponsor ID: 3125-101-009
Conditions: Major Depressive Disorder
Keywords: NMDA receptor, NMDA receptor positive allosteric modulator, pharmacokinetics, biomarker, eeg
Phase: Phase 1
Study type: Interventional
Recruitment status: Completed
Enrolment: 68 participants (actual)
Lead sponsor: Syndeio Biosciences, IncIndustry (pharma, biotech, devices)
Study start: 9 Dec 2016 (actual)
Primary completion: 21 Dec 2017 (actual)
Study completion: 21 Dec 2017 (actual)
First posted: 29 Jul 2021 (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.

To evaluate the safety and tolerability of single ascending doses of zelquistinel in normal human volunteers

Detailed description

Single ascending dose (SAD), double-blind placebo-controlled study in normal human volunteers.

Secondary objectives:

To evaluate the pharmacokinetics (PK) and eeg biomarker of target engagement of zelquistinel following increasing single doses of zelquistinel.

Zelquistinel or Placebo: Dose/Mode of Administration: Single dose; oral

Study design

Primary purpose: Treatment
Allocation: Randomised
Intervention model: Parallel groups
Masking: Triple blind (participant, investigator, outcomes assessor)
Number of arms: 10
Model description: Double blind placebo controlled

Arm	Type	Receives
100 microgram zelquistinel	Experimental	Drug: zelquistinelzelquistinel, 100 microgram tablet, PO, Single Dose with 28 day follow up
1 mg zelquistinel	Experimental	Drug: zelquistinelzelquistinel, 1 mg tablet, PO, Single Dose with 28 day follow up
3 mg zelquistinel	Experimental	Drug: zelquistinelzelquistinel, 3 mg tablet, PO, Single Dose with 28 day follow up
10 mg zelquistinel	Experimental	Drug: zelquistinelzelquistinel, 10 mg tablet, PO, Single Dose with 28 day follow up
25 mg zelquistinel	Experimental	Drug: zelquistinelzelquistinel, 25 mg tablet, PO, Single Dose with 28 day follow up
50 mg zelquistinel	Experimental	Drug: zelquistinelzelquistinel, 50 mg tablet, PO, Single Dose with 28 day follow up
100 mg zelquistinel	Experimental	Drug: zelquistinelzelquistinel, 100 mg tablet, PO, Single Dose with 28 day follow up
1 mg zelquistinel with CSF collection	Experimental	Drug: zelquistinelzelquistinel, 1 mg tablet, PO, Single Dose with 28 day follow up, with CSF collection
10 mg zelquistinel with CSF collection	Experimental	Drug: zelquistinelzelquistinel, 10 mg tablet, PO, Single Dose with 28 day follow up, with CSF collection
Placebo	Placebo comparator	Drug: PlaceboPlacebo tablet, PO, Single Dose with 28 day follow up

Who may qualify

Ages: 18 to 45 years
Sex: All
Healthy volunteers: Accepted
Age groups: Adult

Key inclusion criteria (5 listed)

Agree to effective method of birth control
If female, negative pregnancy test at screening and Day -1
Nonsmoking at least 2 years
BMI 18-30
Supine pulse rate 30-100

Key exclusion criteria (8 listed)

Known hypersensitivity to NMDA receptor drugs
clinically significant disease in any body system
QTcF > 430 ms in males, >450 ms in females
positive test for hepatitis B or C
abnormal liver function tests on Day -1

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
zelquistinelSingle dose of zelquistinel	Drug	1 mg zelquistinel, 1 mg zelquistinel with CSF collection, 10 mg zelquistinel, 10 mg zelquistinel with CSF collection, 100 mg zelquistinel, 100 microgram zelquistinel, 25 mg zelquistinel, 3 mg zelquistinel, 50 mg zelquistinel
PlaceboPlacebo	Drug	Placebo

Primary outcome

Treatment emergent adverse events
Time frame: 28 days
through study completion

3 secondary outcomes

Pharmacokinetics, maximum plasma concentration
Time frame: 24 hours
Pharmacokinetics, time to maximum plasma concentration
Time frame: 24 hours
Pharmacokinetics, area under the curve for plasma concentration
Time frame: 72 hours

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 12 Mar 2026.

Related trials for Major Depressive Disorder

Not yet recruiting
Preventive and Personalized Digital Emotion Regulation Skills Intervention to Reduce Depression and Anxiety in Youths With Adverse Childhood Experiences
Adverse Childhood Experience, Depression / Major Depressive Disorder
RecruitingPhase 4
Biomarker-Guided Antidepressant Selection
Depression - Major Depressive Disorder, Treatment-resistant Depression (TRD)
Recruiting
Targeting Network Dysfunction in Apathy of Late-life Depression Using Digital Therapeutics
Major Depressive Disorder, Apathy
RecruitingObservational study
Student Precarity and Psychiatry
Depressive Disorder, Major, Generalized Anxiety Disorder
Not yet recruiting
Acute Intermittent Hypoxia Therapy for Depression
Major Depressive Disorder (MDD)

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.

Aaron Koenig, MD study chair

Syndeio Biosciences

Questions about this trial

What is this clinical trial studying?

A Phase 1 study testing zelquistinel in people with Major Depressive Disorder, run by Syndeio Biosciences, Inc.

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 5 inclusion and 8 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 12 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.

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?

Treatment emergent adverse events (time frame: 28 days). 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 NCT04981561.

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 12 Mar 2026.