U.S. Long-Acting Naltrexone Implant Research in 2026: What Is Currently Verified
Clinical development of investigational long-acting naltrexone implants is active in the United States in 2026. Current U.S. trial records identify at least two separate implant development programs with recruiting early-phase clinical studies: iSTEP-N and BICX104.
The available evidence should be interpreted carefully. Current studies focus primarily on pharmacokinetics and safety and do not yet establish long-term relapse-prevention effectiveness in people receiving treatment for opioid use disorder.
Published First-in-Human iSTEP-N Study
A first-in-human U.S. study of the investigational iSTEP-N bioresorbable naltrexone implant was published in the Journal of Addiction Medicine on .
Healthy adult volunteers
16 participants
Phase 1 / first-in-human
Completed and published
Participants received either a 4.8 g naltrexone implant, two implants totalling 9.6 g, or placebo implants.
The study primarily evaluated safety and pharmacokinetics, including plasma naltrexone concentrations following implantation.
In the 9.6 g group, mean plasma naltrexone concentrations remained above the study’s stated 2.0 ng/mL opioid-blockade threshold during the 12-week observation period.
Approximately 22% of implant drug content was released during the 12-week study period.
Three of six participants receiving 9.6 g developed seromas. According to the published report, these resolved without intervention. No serious adverse events were reported.
Important limitation
The participants were healthy volunteers rather than people receiving treatment for opioid use disorder. The study evaluated safety and pharmacokinetics rather than relapse, abstinence or overdose outcomes.
It therefore does not establish six-month or one-year relapse-prevention effectiveness.
Primary source:
PubMed — First-in-human iSTEP-N Phase 1 study
Current U.S. iSTEP-N Phase 1b Study
A follow-on U.S. study registered as NCT07064564 is currently recruiting healthy adult volunteers to evaluate two doses of the investigational iSTEP-N implant and compare their pharmacokinetic profiles with monthly extended-release injectable naltrexone.
NCT07064564
Recruiting
Phase 1 / Phase 1b
33 healthy adults
Utah, United States
Interventions
- 9.6 g iSTEP-N naltrexone implant
- 14.4 g iSTEP-N naltrexone implant
- Monthly 380 mg extended-release injectable naltrexone
Comparator
The active comparator is monthly 380 mg extended-release injectable naltrexone, Vivitrol.
Primary outcome
The primary outcome evaluates average plasma naltrexone concentrations at the end of successive four-week intervals during extended follow-up.
The study also evaluates additional pharmacokinetic measurements and treatment-emergent adverse events.
Investigators and institutions
NIH RePORTER identifies Akyso Therapeutics, LLC as the awardee organization for the NIDA-supported development program.
NIH records identify Steven M. Cohen, MD as Contact Principal Investigator/Project Leader and Jeffrey Benner as an additional Principal Investigator on the funded development project.
Clinical trial records identify Todd Bertoch, MD as Principal Investigator associated with CenExel JBR, the Utah clinical research site.
This distinction is important: Akyso is associated with development of the investigational implant, while CenExel JBR is involved in clinical study conduct.
What the study does not yet establish
No clinical efficacy results are currently available from this study. It does not presently establish one-year relapse prevention, superiority to Vivitrol, improved abstinence or reduced overdose risk.
The current study population consists of healthy volunteers rather than people being followed for clinical opioid-use-disorder outcomes.
Primary registry:
ClinicalTrials.gov — NCT07064564
Institutional source:
NIH RePORTER — iSTEP-N development program
Verification checked:
NIH and NIDA Research Support
NIH RePORTER documents National Institute on Drug Abuse support associated with development of the iSTEP-N bioabsorbable long-acting naltrexone implant.
The NIH project record describes human clinical development under an Investigational New Drug framework.
An Investigational New Drug pathway allows an investigational product to be studied in humans. It does not mean that a product has received FDA marketing approval.
Primary source:
NIH RePORTER
A Second U.S. Program: BICX104
A separate U.S. Phase 1 program is evaluating the investigational BICX104 long-acting naltrexone implant.
The trial is registered as NCT07269873 and is recruiting healthy adult volunteers.
NCT07269873
Recruiting
Phase 1
30 healthy adults
Miami, Florida
Study cohorts
- One BICX104 naltrexone implantable pellet
- One BICX104 pellet plus bupropion XL
- Two BICX104 pellets plus bupropion XL
- Vivitrol 380 mg every 28 days
Primary outcomes
The primary outcomes are pharmacokinetic measures including maximum plasma concentration, time to maximum concentration, area under the concentration-time curve and duration of measurable naltrexone exposure.
Safety and adverse events are also monitored.
Investigator and institution
NIH RePORTER identifies BioCorRx Pharmaceuticals Inc. as the awardee organization for the NIDA-funded BICX104 development program.
NIH records identify Katherine Beebe DeVarney, PhD as Contact Principal Investigator/Project Leader for the program.
The appropriate description is therefore a NIDA-funded BioCorRx development program. It should not be described as a trial being conducted by NIDA itself.
Current evidence status
No clinical efficacy results are currently available from this recruiting study.
Because the participants are healthy volunteers and the main outcomes concern pharmacokinetics and safety, the study should not be described as demonstrating effectiveness for opioid use disorder, cocaine use disorder, methamphetamine use disorder or relapse prevention.
Primary registry:
ClinicalTrials.gov — NCT07269873
Institutional source:
NIH RePORTER — BICX104 development program
Verification checked:
What About Columbia University?
Earlier U.S. naltrexone implant research has involved investigators and institutions associated with New York State Psychiatric Institute and the Columbia University research environment.
However, the current verification did not establish that Columbia University is conducting either of the two recruiting 2026 implant studies described above.
The current recruiting programs verified here are associated with Akyso Therapeutics and BioCorRx Pharmaceuticals.
DeBinge therefore does not currently describe the 2026 development as a restarted Columbia University naltrexone implant trial unless a new primary institutional or clinical-trial source establishes that.
Current U.S. Regulatory Status
Long-acting naltrexone implants remain investigational in the United States.
The U.S. Food and Drug Administration currently identifies naltrexone as one of the medications used for opioid use disorder and lists extended-release injectable naltrexone, Vivitrol, as an approved formulation.
A long-acting naltrexone implant is not currently listed there as an FDA-approved medication for opioid use disorder.
DeBinge therefore does not describe an investigational naltrexone implant as FDA-approved in the United States.
Primary source:
U.S. Food and Drug Administration — Medications for Opioid Use Disorder
FDA information checked:
What the Current U.S. Evidence Does Not Yet Establish
Current U.S. implant studies are primarily early-stage pharmacokinetic and safety studies.
They do not currently establish that an investigational long-acting naltrexone implant:
- prevents relapse for one year;
- guarantees abstinence;
- prevents overdose;
- is clinically superior to monthly injectable naltrexone;
- has demonstrated long-term clinical effectiveness in people with opioid use disorder;
- has demonstrated effectiveness for cocaine or methamphetamine use disorder;
- has FDA marketing approval in the United States.
Those questions require appropriate clinical studies involving relevant patient populations and clinical outcomes.
What the 2026 Developments Mean
The strongest defensible conclusion is that U.S. development of investigational long-acting naltrexone implants is active and progressing.
A first-in-human iSTEP-N study has produced peer-reviewed Phase 1 evidence, while at least two separate investigational implant development programs have recruiting early-phase clinical studies in the United States.
The verified institutional picture also shows that these are distinct development programs rather than a single university-led project.
Akyso Therapeutics is associated with the iSTEP-N development program, with NIDA research support and clinical study involvement from CenExel JBR. BioCorRx Pharmaceuticals is developing BICX104 through a separate NIDA-funded program.
These developments are scientifically relevant, but they should not be interpreted as evidence of FDA marketing approval or proof of long-term relapse-prevention effectiveness.
Clinical expert profile: Dr Fergus Law, BSc, MBChB, FRCPsych , Consultant Psychiatrist specialising in substance misuse and addiction.
This notice does not indicate that Dr Law has reviewed or approved this article.