A Phase 2 Safety, Tolerability, PK, and Efficacy Study of CS-1103 Following Fentanyl Challenge With Naloxone Blockade

NCT07459166 | Not Yet Recruiting Phase 2 FDA Drug

• 2 other identifiers: CS-1103-035UG3DA059286
• Study Type: interventional
• Target: 16
• Locations: 1 country
• Sites: 1

Brief 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).

Conditions

Fentanyl Overdose; Fentanyl Poisoning

Outcome Measures

Primary Outcomes (6)

• Number of participants with CS-1103-related adverse events (AEs) assessed by physical examinations

  Physical examinations

  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

  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

  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

  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

  48 hours

• Time course and magnitude of urine excretion of fentanyl

  Measurement of concentration of fentanyl in urine

  48 hours

Secondary Outcomes (2)

• Effect of CS-1103 and fentanyl on QT interval

  48 hours

• Effect of CS-1103 on the naloxone plasma and urine PK, if any

  48 hours

Study Arms (2)

Placebo

PLACEBO COMPARATOR

Participants receive naloxone blockade (400 μg, IV), followed by fentanyl (200 μg, IV), followed by placebo (saline).

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).

Drug: Naloxone Hydrochloride; Drug: Fentanyl; Drug: CS-1103

Interventions

Naloxone Hydrochloride DRUG

Naloxone for intravenous administration

Active; Placebo

Fentanyl DRUG

Fentanyl for intravenous administration

Active; Placebo

Sterile Saline DRUG

Sterile Saline for intravenous administration

Placebo

CS-1103 DRUG

CS-1103 for intravenous administration

Active

Eligibility Criteria

• Age: 18 Years - 55 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• 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.

You may not qualify if:

• Estimated glomerular filtration rate \<60 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.

Sponsors & Collaborators

• Clear Scientific, Inc.: lead
• National Institute on Drug Abuse (NIDA): collaborator

Study Sites (1)

California Clinical Trials Medical Group

Glendale, California, 91206, United States

Location

MeSH Terms

Interventions

Naloxone; Fentanyl

Intervention Hierarchy (Ancestors)

Morphinans; Opiate Alkaloids; Alkaloids; Heterocyclic Compounds; Heterocyclic Compounds, Bridged-Ring; Heterocyclic Compounds, 4 or More Rings; Heterocyclic Compounds, Fused-Ring; Phenanthrenes; Polycyclic Aromatic Hydrocarbons; Polycyclic Compounds; Piperidines; Heterocyclic Compounds, 1-Ring

Study Officials

• Xinhua Li, Ph.D.

  Clear Scientific, Inc.

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Anna Del Rosario, B.S.

CONTACT

617-621-8500; adelrosario@clearsci.com

Piercen Oliver, Ph.D.

CONTACT

617-621-8500; poliver@clearsci.com

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: March 4, 2026
• First Posted: March 9, 2026
• Study Start: April 1, 2026
• Primary Completion (Estimated): July 1, 2026
• Study Completion (Estimated): October 1, 2026
• Last Updated: March 27, 2026

Record last verified: 2026-03

Locations

US (1)