Fentanyl OverdosePhase 2NCT07459166
A Phase 2 Safety, Tolerability, PK, and Efficacy Study of CS-1103 Following Fentanyl Challenge With Naloxone Blockade
A Phase 2 study testing Naloxone Hydrochloride, Fentanyl and Sterile Saline in people with Fentanyl Overdose and Fentanyl Poisoning, run by Clear Scientific, Inc. at 1 site in United States.
Trial summary
The purpose of the study is to evaluate the safety, tolerability, pharmacokinetics, and efficacy of CS-1103 (1,000 mg), given by intravenous (IV) infusion in healthy participants in the presence of a clinically relevant dose of fentanyl (200 μg, IV), with naloxone blockade (400 μg, IV). Read more about this study
- Who is it for?
- Ages 18 to 55 yearsHealthy volunteers can take part
- Conditions the study is for
- Fentanyl Overdose, Fentanyl Poisoning
- What is being tested?
- Naloxone Hydrochloride, Fentanyl and Sterile Saline
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 16 participants
- Where
- 1 siteUnited States
- Study dates
- 28 May 2026to Oct 2026
- Phase
- Phase 2
- 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 55 years
- All sexes
- Healthy volunteers accepted
- Adult
Major Inclusion Criteria:
- Healthy participants aged 18 to 55 years, inclusive;
- Have prior experience with opioids, such as from a dental procedure, chronic pain management, or previous inpatient surgical procedure;
- A body mass index between 18.0 to 30.0 kg/m2, inclusive, and a minimum body weight of 56 kg;
- Females must not be lactating and must have a negative pregnancy test during screening and admission.
Major Exclusion Criteria:
- Estimated glomerular filtration rate <90 mL/min/1.73 m2;
- History of cardiovascular disease;
- History of any clinically important disease or disorder which, in the opinion of the Investigator, may interfere with safe study participation.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
California Clinical Trials Medical Group
Glendale, California, 91206
Lev Gertsik, M.D., 888-228-7425, study.losangeles@parexel.com
About this study
Official title: A Phase 2 Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Efficacy of a Single Dose of Intravenous CS 1103 Following a Single Intravenous Dose of Fentanyl in Healthy Subjects With Naloxone Blockade
The purpose of the study is to evaluate the safety, tolerability, pharmacokinetics, and efficacy of CS-1103 (1,000 mg), given by intravenous (IV) infusion in healthy participants in the presence of a clinically relevant dose of fentanyl (200 μg, IV), with naloxone blockade (400 μg, IV).
- Conditions
- Fentanyl Overdose, Fentanyl Poisoning
- Being tested
- Naloxone Hydrochloride, Fentanyl, Sterile Saline, CS-1103
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Naloxone HydrochlorideDrug
Naloxone for intravenous administration
FentanylDrug
Fentanyl for intravenous administration
Sterile SalineDrug
Sterile Saline for intravenous administration
CS-1103Drug
CS-1103 for intravenous administration
| Study group | Role | What they receive |
|---|---|---|
| Placebo | Placebo comparator | Participants receive naloxone blockade (400 μg, IV), followed by fentanyl (200 μg, IV), followed by placebo (saline). Receives: Drug: Naloxone Hydrochloride; Drug: Fentanyl; Drug: Sterile Saline |
| Active | Active comparator | Participants receive naloxone blockade (400 μg, IV), followed by fentanyl (200 μg, IV), followed by CS-1103 (1,000 mg, IV). Receives: Drug: Naloxone Hydrochloride; Drug: Fentanyl; Drug: CS-1103 |
What is being measured
The primary outcome is the main question the study is designed to answer.
Number of participants with CS-1103-related adverse events (AEs) assessed by physical examinations
Physical examinations
Measured: 3 days plus follow-up on Day 10
Number of participants with CS-1103-related adverse events (AEs) assessed by electrocardiograms (ECGs)
Digital 12-lead electrocardiograms (ECGs). Any correlation between CS-1103 plasma concentrations and changes in QT intervals will be noted
Measured: 3 days plus follow-up on Day 10
Number of participants with CS-1103-related adverse events (AEs) assessed by vital signs
Blood pressure, pulse rate, respiratory rate, oxygen saturation, and body temperature
Measured: 3 days plus follow-up on Day 10
Number of participants with CS-1103-related adverse events (AEs) assessed by laboratory parameters
Clinical chemistry, hematology, coagulation, and urinalysis
Measured: 3 days plus follow-up on Day 10
Time course of CS-1103 blood and urine concentrations
Measurement of plasma and urine concentrations of CS-1103
Measured: 48 hours
Time course and magnitude of urine excretion of fentanyl
Measurement of concentration of fentanyl in urine
Measured: 48 hours
Secondary outcomes (2)
Effect of CS-1103 and fentanyl on QT interval
Concentration-QT correlation performed on baseline-corrected QTcF time-matched with PK for fentanyl and CS-1103 in plasma
Measured: 48 hours
Effect of CS-1103 on the naloxone plasma and urine PK, if any
Measurement of standard urine and plasma PK parameters between placebo and CS-1103 treated participants
Measured: 48 hours
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted9 Mar 2026
- Study start28 May 2026
- Primary completion22 Jul 2026
- Study completionOct 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Fentanyl OverdoseStudies 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 2
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 16 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Clear Scientific, Inc.
- Sponsor type
- Industry (pharma, biotech, devices)
- Collaborators
- National Institute on Drug Abuse (NIDA)
- Responsible party
- Sponsor
- Investigators
- Xinhua Li, Ph.D., Principal investigator, Clear Scientific, Inc.
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07459166
- Sponsor's protocol ID
- CS-1103-03
- Other IDs
- 5UG3DA059286
- Status last verified
- Aug 2026
- First submitted
- 4 Mar 2026
- Last updated
- 24 Aug 2026
- Results posted
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 24 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 2 Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Efficacy of a Single Dose of Intravenous CS 1103 Following a Single Intravenous Dose of Fentanyl in Healthy Subjects With Naloxone Blockade
- ClinicalTrials.gov ID
- NCT07459166
- Acronym / sponsor ID
- CS-1103-03
- Conditions
- Fentanyl Overdose, Fentanyl Poisoning
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 16 participants (estimated)
- Lead sponsor
- Clear Scientific, Inc.Industry (pharma, biotech, devices)
- Collaborators
- National Institute on Drug Abuse (NIDA)
- Study start
- 28 May 2026 (actual)
- Primary completion
- 22 Jul 2026 (actual)
- Study completion
- Oct 2026 (estimated)
- First posted
- 9 Mar 2026 (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.
The purpose of the study is to evaluate the safety, tolerability, pharmacokinetics, and efficacy of CS-1103 (1,000 mg), given by intravenous (IV) infusion in healthy participants in the presence of a clinically relevant dose of fentanyl (200 μg, IV), with naloxone blockade (400 μg, IV).
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Placebo | Placebo comparator | Drug: Naloxone Hydrochloride, Drug: Fentanyl, Drug: Sterile SalineParticipants receive naloxone blockade (400 μg, IV), followed by fentanyl (200 μg, IV), followed by placebo (saline). |
| Active | Active comparator | Drug: Naloxone Hydrochloride, Drug: Fentanyl, Drug: CS-1103Participants receive naloxone blockade (400 μg, IV), followed by fentanyl (200 μg, IV), followed by CS-1103 (1,000 mg, IV). |
Who may qualify
- Ages
- 18 to 55 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
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 |
|---|---|---|
| Naloxone HydrochlorideNaloxone for intravenous administration | Drug | Active, Placebo |
| FentanylFentanyl for intravenous administration | Drug | Active, Placebo |
| Sterile SalineSterile Saline for intravenous administration | Drug | Placebo |
| CS-1103CS-1103 for intravenous administration | Drug | Active |
Primary outcome
Number of participants with CS-1103-related adverse events (AEs) assessed by physical examinations
Time frame: 3 days plus follow-up on Day 10
Physical examinations
Number of participants with CS-1103-related adverse events (AEs) assessed by electrocardiograms (ECGs)
Time frame: 3 days plus follow-up on Day 10
Digital 12-lead electrocardiograms (ECGs). Any correlation between CS-1103 plasma concentrations and changes in QT intervals will be noted
Number of participants with CS-1103-related adverse events (AEs) assessed by vital signs
Time frame: 3 days plus follow-up on Day 10
Blood pressure, pulse rate, respiratory rate, oxygen saturation, and body temperature
Number of participants with CS-1103-related adverse events (AEs) assessed by laboratory parameters
Time frame: 3 days plus follow-up on Day 10
Clinical chemistry, hematology, coagulation, and urinalysis
Time course of CS-1103 blood and urine concentrations
Time frame: 48 hours
Measurement of plasma and urine concentrations of CS-1103
Time course and magnitude of urine excretion of fentanyl
Time frame: 48 hours
Measurement of concentration of fentanyl in urine
2 secondary outcomes
Effect of CS-1103 and fentanyl on QT interval
Time frame: 48 hours
Effect of CS-1103 on the naloxone plasma and urine PK, if any
Time frame: 48 hours
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 24 Aug 2026.
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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.
Xinhua Li, Ph.D. principal investigator
Clear Scientific, Inc.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing Naloxone Hydrochloride, Fentanyl and Sterile Saline in people with Fentanyl Overdose and Fentanyl Poisoning, run by Clear Scientific, Inc. 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?
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: looking for participants now, as of the sponsor's last update on 24 Aug 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. 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 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
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?
Contact Anna Del Rosario, B.S. (617-621-8500, adelrosario@clearsci.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Number of participants with CS-1103-related adverse events (AEs) assessed by physical examinations (time frame: 3 days plus follow-up on Day 10). The study lists 6 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 24 Aug 2026.