white → brown1 → purple1 → blue1
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WARNINGDANGER OF DEATH
High doses alone or ordinary doses in combination with other depressants can fatally stop breathing.
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Isomethadone
Isomethadone is a synthetic opioid analgesic structurally related to methadone. It was formerly available as a pharmaceutical product but has since been withdrawn from the market and is seldom encountered today. It is reported to possess approximately twice the analgesic potency of methadone and is said to produce euphoric effects. As with other opioids, it carries a risk of habit formation and respiratory depression.
Dosage & Duration
Dosage
Doses are population estimates that vary widely between individuals.
Threshold~1.5 mg
Light1.5-2.5 mg
Moderate2.5-7.5 mg
Strong7.5-15 mg
Heavy15+ mg
Duration
Onset30-90 minutes
After Effects1-24 hours
Total30-40 hours
Subjective Effects
Legacy content. A statistically backed ontology from Mindstate Design Labs is coming soon.
Isomethadone produces a classic opioid experience centered on euphoria, mood lift, and physical relaxation, consistent with its status as a structural analogue of methadone. As a withdrawn pharmaceutical that is seldom encountered today, detailed experience reports are scarce, but the available accounts describe a euphoric, analgesic effect profile accompanied by the typical constellation of opioid side effects.
Physical
The body experience is dominated by pain relief and a relaxed, comfortable heaviness, alongside common opioid side effects such as itchiness, dry mouth, constipation, and constricted pupils.
Bodily
Uncomfortable
Side effects typical of opioids accompany the experience.
Cognitive
The mental state is characterized by euphoria and an elevated mood, without notable alteration of perception or thought structure.
Pharmacology
Pharmacodynamics
Isomethadone acts as an agonist at both the μ-opioid and δ-opioid receptors. The (S)-enantiomer is reported to be more potent than the (R)-enantiomer.
Pharmacokinetics
Absorption & half-lifenot documented yetMetabolitesnone documented yet
Interactions
Interactions not written up yet
An unlisted combination is an unknown one, not a safe one. Check a dedicated combination chart before mixing.
Tolerance
Tolerance timelines are rules of thumb, not exact schedules, and vary widely between individuals and use patterns.
Cross Tolerance
Opioids
Harm Potential
Addiction & Dependence
Psychological
Classified as habit-forming.
History & Culture
Isomethadone, also known by the alternative name isoamidone, is a synthetic opioid analgesic structurally related to methadone. It was previously marketed as a pharmaceutical product under the trade name Liden, where it saw clinical use for both pain management and cough suppression. The compound has since been withdrawn from the pharmaceutical market and is no longer commercially available as a medication.
Legality
International
UN Single Convention on Narcotic Drugs 1961 (Schedule I)
By Country
Illegal1
United StatesIllegalFederal law lists isomethadone by exact name in Schedule II, together with its possible isomers, esters, ethers, salts, and salts of those forms. Possession, manufacture, distribution, and dispensing are unlawful except when authorized under federal controlled-substances law. Import and export are also restricted, subject to the statutory exceptions, required findings, destination controls, and permits in 21 U.S.C. §§ 952–953; separate state, District of Columbia, territorial, tribal, and local laws may also apply.
References
Citations
- eCFR — 21 C.F.R. § 1308.12, Schedule II (2026-09-01). ecfr.gov (n.d.). https://www.ecfr.gov/api/renderer/v1/content/enhanced/2026-09-01/title-21?section=1308.121
- DEA Controlled Substances — Alphabetical Order (27 August 2026). deadiversion.usdoj.gov (n.d.). https://www.deadiversion.usdoj.gov/schedules/orangebook/c_cs_alpha.pdf1
- 21 U.S.C. § 812 — Schedules of controlled substances. uscode.house.gov (n.d.). https://uscode.house.gov/view.xhtml?req=granuleid%3AUSC-prelim-title21-section812&num=0&edition=prelim1
- 21 U.S.C. § 801 statutory note — Controlled Substances Act effective date. uscode.house.gov (n.d.). https://uscode.house.gov/view.xhtml?req=granuleid%3AUSC-prelim-title21-section801&num=0&edition=prelim1
- 21 U.S.C. § 841 — Prohibited acts A. uscode.house.gov (n.d.). https://uscode.house.gov/view.xhtml?req=granuleid%3AUSC-prelim-title21-section841&num=0&edition=prelim1
- 21 U.S.C. § 844 — Penalties for simple possession. uscode.house.gov (n.d.). https://uscode.house.gov/view.xhtml?req=granuleid%3AUSC-prelim-title21-section844&num=0&edition=prelim1
- 21 U.S.C. § 952 — Importation of controlled substances. uscode.house.gov (n.d.). https://uscode.house.gov/view.xhtml?req=granuleid%3AUSC-prelim-title21-section952&num=0&edition=prelim1
- 21 U.S.C. § 953 — Exportation of controlled substances. uscode.house.gov (n.d.). https://uscode.house.gov/view.xhtml?req=granuleid%3AUSC-prelim-title21-section953&num=0&edition=prelim1
- Final Adjusted Aggregate Production Quotas for Schedule I and II Controlled Substances for 2014, 79 FR 50700. federalregister.gov (n.d.). https://www.federalregister.gov/documents/full_text/text/2014/08/25/2014-20137.txt1
Article Status
Step 1 · Automated synthesisAn autonomous workflow built by Josie Kins compiled this article's foundation from information published across the web.
- Step 2 · First-pass reviewPending
Not yet reviewed — this article is pending editorial review by Lyrea.
- Step 3 · Citation reviewPending
No one has reviewed this article's citations yet. That second pass checks each claim against the source it cites.
Recent changes7 human edits · latest
Times are UTCNewest first
24 January 2026
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
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