CounterX Therapeutics Announces Publication Demonstrating CTRX-101, an Anti-Fentanyl Monoclonal Antibody Therapy, Reverses Fentanyl-Induced Overdose in Preclinical Model

SEATTLE, Oct. 29, 2025 /PRNewswire/ -- CounterX Therapeutics, Inc., a biotechnology company focused on developing novel antibody therapeutics and vaccines to address opioid overdose and dependence, today announced the publication of its latest peer-reviewed preclinical study in The Journal of Pharmacology and Experimental Therapeutics.

The study highlights the potential of CTRX-101, CounterX Therapeutics' proprietary anti-fentanyl monoclonal antibody, to rapidly reverse life-threatening respiratory depression caused by exposure to fentanyl and its analogs. Conducted in a translational preclinical model, the study demonstrates that administration of the CTRX-101 effectively restores normal breathing following fentanyl overdose. 

Fentanyl overdose is the leading cause of death for Americans aged 18 – 45. Fentanyl overdoses result in approximately 50,000 deaths and more than 700,000 emergency department visits each year.  CTRX-101 is being developed for the prevention and treatment of fentanyl overdose in patients with moderate to severe opioid use disorder (OUD).

"These findings provide strong supporting evidence for the clinical development of CTRX-101 to address lethal overdoses with fentanyl," said Dr. Marco Pravetoni, Founder and Chief Scientific Officer at CounterX Therapeutics. "Unlike existing therapies that rely on opioid receptor blockade, CTRX-101 binds to fentanyl, sequesters it in the bloodstream, and prevents its lethal effects on the brain and respiratory system."

The publication reinforces CounterX Therapeutics' leadership in developing novel therapies and builds on previous preclinical studies of CTRX-101 that demonstrate efficacy, selectivity, and safety for the prevention and treatment of acute fentanyl overdose.

"This exciting study marks a key milestone in translating products developed with our CounterXL™ Platform from preclinical models to potential human application," said Dr. Shawn Iadonato, Chief Executive Officer at CounterX Therapeutics. "We believe CTRX-101 has the potential to provide a differentiated pre-exposure prophylaxis treatment for fentanyl and complement current standards of care in opioid use disorders."

The full article is available for viewing under Publications section of the company's website at https://counterxtherapeutics.com/.

About CounterX Therapeutics
CounterX Therapeutics is at the forefront of the battle against the opioid epidemic, exploiting cutting-edge biotechnology to develop life-saving therapeutics and vaccines. We combine scientific expertise with an experienced leadership team and a deep commitment to social impact. Our groundbreaking antibody therapies are designed to blunt the effects of opioids, reduce the risk of overdose and a provide a path to recovery. Additionally, our pioneering vaccine technology aims to prevent addiction relapse by blocking the euphoric effects of opioids, empowering individuals to maintain a long-term recovery. Dr. Marco Pravetoni is the Founder and Chief Scientific Officer at CounterX Therapeutics and Professor of Psychiatry and Behavioral Sciences at the University of Washington School of Medicine.

CTRX-101:
CTRX-101, is a monoclonal antibody against fentanyl that is in development for the prevention of accidental overdose in high-risk patients. It is a long-acting subcutaneous injectable product that is not an opioid or controlled substance. CTRX-101 was well-tolerated in preclinical models with no serious adverse events when used in combination with other medications for opioid use disorder (OUD). It is not expected to cause opioid withdrawal and may be safe when used in combination with other medications.

FOR FURTHER INFORMATION, PLEASE CONTACT:
CounterX Therapeutics
Jacques Bouchy
Chief Business Officer
206.486.4755
[email protected]

SOURCE CounterX Therapeutics