Psychiatry · Clinical trials
Opioid Use Disorder Clinical Trials
Approved therapies, the pivotal-trial endpoints they were judged on, the magnitude of benefit — and the drugs that failed their endpoints, and why.
Indication overview
About opioid use disorder — and why its trials are hard
Opioid Use Disorder (OUD) is a chronic, relapsing condition driving a large share of U.S. overdose deaths. Medications for OUD (MOUD) are the evidence-based standard and reduce mortality, transmission of infection, and relapse. Three agents are FDA-approved. Methadone, a full mu-opioid agonist, has been used for maintenance since 1972 and is dispensed through regulated opioid treatment programs. Buprenorphine, a partial agonist with a ceiling on respiratory depression, was approved in 2002 (often combined with naloxone as Suboxone) and can be office-prescribed, greatly expanding access. Extended-release naltrexone, a full antagonist, was approved for OUD relapse prevention in 2010 but requires full detoxification before initiation, which limits real-world uptake. Agonist therapies (methadone, buprenorphine) show the strongest retention and mortality benefits. Persistent challenges include induction onto naltrexone, treatment retention, stigma, and access. Newer long-acting buprenorphine injectables (e.g., Sublocade) address adherence, underscoring ongoing innovation within existing pharmacologic mechanisms rather than novel targets.
Approved therapies & pivotal evidence
What's been approved — and by how much it moved the endpoint
| Drug (brand) | Approved | Setting | Pivotal trial | Primary endpoint | Magnitude of benefit |
|---|---|---|---|---|---|
| Methadone (Dolophine / Methadose) | 1972 (approved for maintenance treatment of opioid dependence) | Maintenance/withdrawal management in regulated opioid treatment programs | Decades of RCTs and Cochrane reviews (methadone maintenance vs placebo/no treatment) | Treatment retention and illicit opioid use | Cochrane: methadone maintenance markedly improves retention and reduces heroin use vs non-agonist approaches; associated with lower all-cause and overdose mortality |
| Buprenorphine (with naloxone) (Subutex / Suboxone / Sublocade) | 2002 (sublingual); 2017 (extended-release injectable, Sublocade) | Office-based maintenance treatment of OUD | Pivotal buprenorphine/naloxone RCTs (Fudala et al., NEJM 2003) | Opioid-negative urine tests / retention | Significantly higher opioid-negative urines and retention vs placebo; comparable efficacy to moderate-dose methadone with better safety margin |
| Naltrexone (extended-release) (Vivitrol) | 2010 (for OUD relapse prevention) | Relapse prevention after opioid detoxification | Krupitsky et al., Lancet 2011 (Russia RCT) | Confirmed abstinence / opioid-free weeks | XR-naltrexone increased confirmed opioid-free weeks (median 90% vs 35% for placebo) and improved retention among successfully inducted patients |
Where trials have failed
Drugs that missed their endpoint — and what contributed
The most instructive lessons in opioid use disorder development come from programmes that failed the endpoint that mattered.
| Drug / trial | Endpoint outcome | What contributed |
|---|---|---|
| Extended-release naltrexone (induction challenge) — X:BOT (Lee et al., Lancet 2018) | Failed to match buprenorphine-naloxone on relapse when analyzed intention-to-treat because many patients could not be inducted | Required full detoxification before start; substantial induction failure led to more early relapses, limiting practical effectiveness |
| Lofexidine — Withdrawal RCTs (approved 2018 as Lucemyra) | Approved only to mitigate acute withdrawal symptoms, not as maintenance treatment for OUD | Alpha-2 agonist does not treat the underlying disorder or prevent relapse; benefit limited to short-term withdrawal, not long-term outcomes |
Choosing the right endpoint
Primary endpoints that matter in opioid use disorder trials
- Treatment retention — Time in treatment; strongly predicts survival and reduced illicit use
- Opioid-negative urine drug screens — Objective biomarker of abstinence used across MOUD trials
- All-cause and overdose mortality — Agonist therapies show robust mortality reduction in cohort and RCT data
- Successful induction — Especially critical for antagonist therapy; failure to induct drives XR-naltrexone underperformance
How iNGENū runs opioid use disorder trials
Physician-led design, built for FDA submission
Endpoint & biomarker strategy
Board-certified specialists design endpoints and patient selection aligned to current FDA guidance for this indication.
FDA-ready data
Built to ICH-GCP and 21 CFR 312.120, with direct FDA submission — data accepted by the FDA, EMA and MHRA.
Faster, lower-cost delivery
~4-week ethics via the TGA CTN scheme, up to 43.5% R&D rebate, and 80–90% below US CRO cost.
Request a fixed-milestone proposal and a tailored endpoint & feasibility summary for this indication.
Frequently asked questions
Opioid Use Disorder clinical trials — FAQs
Which MOUD is most effective?
Why is XR-naltrexone used less?
Is naloxone a treatment for OUD?
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