The single-site study involved 16 healthy adult participants, all of whom received both fentanyl and naloxone to replicate real-world overdose scenarios. Unlike current treatments that rely on receptor displacement, CS-1103 acts as a small-molecule sequestrant, effectively clearing the opioid from the bloodstream and brain. The trial confirmed that the drug accelerates fentanyl excretion into urine without interfering with the life-saving effects of naloxone.

Chief Executive Officer Shekar Shetty noted that the therapy could prevent fatal re-narcotization and reduce the severity of precipitated withdrawal. By clearing the toxin, the drug may simplify the transition to addiction treatments like buprenorphine and methadone. The intravenous dose proved well-tolerated among all participants, with no serious adverse events reported during the study.

Clear Scientific, co-founded by Harvard Professor George M. Whitesides, plans to initiate Phase 3 trials by the first half of 2027. Supported by the National Institute on Drug Abuse, the company is developing these sequestrants to address a crisis that saw over 55,000 fatalities in 2024. While the technology remains investigational, its mechanism offers a new approach to managing synthetic opioid toxicity in crowded emergency departments.