Frequently asked questions

SR-17018 is a synthetic opioid first described by scientists at the Scripps Research Institute in 2017. It activates the μ-opioid receptor — the same receptor as morphine and fentanyl — but with unusual, only partial activity. It has not been approved for any medical use, and there are no completed human clinical trials.

SR-17018 is not specifically scheduled in many countries, but unscheduled is not the same as legal. In the United States, federal prosecutors can treat it as a Schedule I substance under the Federal Analogue Act when it is intended for human consumption. Germany controls it under the NpSG (since 2025). The UK Psychoactive Substances Act 2016 likely applies. This is not legal advice; verify in your jurisdiction.

There is no clinically validated dose for SR-17018 — no human trials have been completed. We document community-reported dose ranges descriptively on the protocols page, with strong disclaimers. They are not recommendations.

In mice, the half-life is approximately 6–8 hours, with a brain-to-plasma ratio of about 3:1. Self-reports describe an effective duration of 6–12 hours per oral dose in humans, but no formal human pharmacokinetic profile has been published.

Yes. Despite SR-17018's non-competitive binding kinetics, orthosteric antagonists — naloxone (Narcan), naltrexone, cyprodime — fully reverse SR-17018-mediated μ-opioid receptor activation in cellular and animal studies. Because SR-17018's duration of action can be long, repeat doses of naloxone may be needed.

Yes, at higher doses — particularly with oral administration. The 'no respiratory depression' claim from the original 2017 paper has not held up cleanly. The original work used intraperitoneal dosing in mice; oral dosing (the only route used in humans) does produce significant respiratory depression in mice. SR-17018 has a wider therapeutic window than morphine or fentanyl in mouse parenteral assays, but it is not free of breathing risk.

Yes. SR-17018 produces dependence in mice, with a clear withdrawal syndrome on discontinuation (Kudla et al., 2022). Self-reports describe post-acute withdrawal-like symptoms after stopping. The compound is not free of dependence liability.

Both are partial μ-opioid receptor agonists with low intrinsic efficacy. Buprenorphine is FDA-approved for opioid use disorder, has decades of clinical data, and is dose-controlled. SR-17018 has none of these things. SR-17018's binding kinetics are markedly different — non-competitive and slowly reversible, rather than competitive — but the clinical comparison strongly favors buprenorphine for any actual treatment context.

Standard hospital and workplace immunoassay opioid panels do not detect SR-17018. Forensic confirmation requires LC–MS/MS or LC–HRMS with appropriate reference standards. A negative urine opioid screen does not rule out SR-17018 use.

Cold turkey means stopping all opioid use abruptly, with nothing to soften withdrawal — physically painful, and the post-withdrawal tolerance drop can make a relapse fatal. The substitution-and-taper approach involves swapping SR-17018 for the original opioid, holding steady to stabilize, then tapering the SR-17018. Both approaches exist outside the medical system; the evidence-based equivalent is a buprenorphine or methadone program from a licensed clinician.

It is safer than morphine on the specific therapeutic-window measurement reported in mouse parenteral experiments — but that does not translate cleanly to human safety. Oral dosing produces respiratory depression. Long-term toxicity is unknown. There is no safety database in humans.

We don't link to vendors, run affiliate programs, or accept vendor funding. The compound is widely sold by research-chemical vendors with 'not for human consumption' disclaimers; identity, purity, and quality in that market are unregulated. Linking to a specific vendor would imply endorsement we cannot make. Our independent testing program is the answer to the actual underlying question — what is in the material being sold.

Yes. SR-17018 is an opioid; oral doses meaningfully above community-reported ranges produce respiratory depression in animals — the same mechanism that causes opioid overdose deaths. Naloxone reverses SR-17018-mediated overdose, but repeat doses may be needed because SR-17018 can outlast a single naloxone dose. Combining SR-17018 with other CNS depressants (benzodiazepines, alcohol, gabapentinoids, other opioids) substantially increases the risk.

It produces dependence in mice — a clear withdrawal syndrome on discontinuation, plus rewarding effects in conditioned place preference. People who use it report withdrawal-like symptoms after stopping. Reinforcing strength in monkey self-administration was lower than heroin and comparable to buprenorphine. Lower than heroin is not the same as 'not addictive.'

Make sure naloxone (Narcan) is in the home and that someone knows how to use it. Don't combine with other CNS depressants. Don't be alone when first using a new batch. Connect to evidence-based treatment options — methadone, buprenorphine, and extended-release naltrexone are all FDA-approved for opioid use disorder, and a licensed clinician can prescribe and supervise them. SAMHSA helpline 1-800-662-HELP (4357) is a free starting point.

Physical dependence is your body adapting to a drug, so stopping produces withdrawal symptoms — it can happen with any opioid (including SR-17018), some antidepressants, and many other medications. Addiction is a behavioral pattern of compulsive use despite harm. They overlap but aren't the same. SR-17018 produces clear physical dependence in animals; whether it produces addiction in humans is not formally studied.

A biased agonist is a drug that selectively activates one signaling pathway over another at a receptor that has more than one downstream pathway. At the μ-opioid receptor, the two pathways are G-protein signaling and β-arrestin2 recruitment. The original idea behind SR-17018 was that biasing toward G-protein signaling could deliver pain relief without the dangerous side effects. Follow-up research has substantially complicated that idea.

Most public self-reports are on the subreddits r/Opioid_RCs and r/researchchemicals. These reports are anecdotal, unverified, subject to severe selection and survivorship bias, and may reference misidentified material. We aggregate the most-consistent observations on our reported effects page.