Heroin

# Research Output: Heroin (Diacetylmorphine)

## Chemical Identity

**Verified from PubChem CID 5462328 and NIST WebBook CAS 561-27-3:**

- **Systematic/IUPAC name:** [(4R,4aR,7S,7aR,12bS)-9-acetyloxy-3-methyl-2,4,4a,7,7a,13-hexahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-7-yl] acetate
- **Common synonym:** Diamorphine (UK clinical name)
- **Molecular formula:** C₂₁H₂₃NO₅
- **Molecular weight:** 369.4 g/mol
- **CAS registry number:** 561-27-3
- **InChIKey:** GVGLGOZIDCSQPN-PVHGPHFFSA-N
- **PubChem CID:** 5462328
- **Melting point:** 173°C (NIST [Ref 33])
- **Boiling point:** 272–274°C at 12 mmHg (NIST [Ref 33])

**Physical forms:**
South-west Asian heroin (predominant in Europe) exists as a brown free-base powder, insoluble in water but soluble in organic solvents. South-east Asian heroin is a white hydrochloride salt, water-soluble but insoluble in organic solvents (EUDA [Ref 29]).

**Discrepancies with seed data:**
- Brief lists SMILES and molecular formula/weight as empty — these are now confirmed: C₂₁H₂₃NO₅, MW 369.4, InChIKey GVGLGOZIDCSQPN-PVHGPHFFSA-N.
- PubChem CID was absent in the brief — confirmed as 5462328.
- The canonical SMILES could not be retrieved from PubChem directly (JavaScript-dependent page); the IUPAC name and InChIKey are confirmed API-verified.

---

## Pharmacology

### Mechanism of Action

Heroin (diacetylmorphine) is a semi-synthetic opioid that acts primarily as a **prodrug**. After administration, it undergoes rapid deacetylation to **6-monoacetylmorphine (6-MAM)**, which is then further deacetylated to **morphine**. Morphine is subsequently glucuronidated to **morphine-3-glucuronide (M3G)** and **morphine-6-glucuronide (M6G)** (Milella et al. 2023 [Ref 1]).

However, the prodrug framing is oversimplified. Current evidence argues for a more complex interplay: heroin itself may have some direct CNS activity, and the sequential actions of heroin, 6-MAM, morphine, and M6G only partially overlap, producing the distinctive temporal pattern of heroin's effects (Milella et al. 2023 [Ref 1]).

**Key pharmacological insight:** 6-MAM — not morphine — is the primary mediator of the **rapid neural effects** of intravenous heroin. Studies using nucleus accumbens oxygen sensors in freely moving rats showed 6-MAM produced similar biphasic changes to heroin (respiratory depression + cerebral vasodilation), while morphine produced only weak increases. The stronger response to heroin vs. 6-MAM reflects heroin's higher CNS permeability and its in-brain conversion to 6-MAM (Perekopskiy & Kiyatkin 2019 [Ref 3]).

### Receptor Binding

Heroin itself exhibits **relatively low direct affinity** for opioid receptors, acting primarily through its active metabolites 6-MAM and morphine. Both 6-MAM and heroin are more lipid-soluble than morphine, enabling faster and more complete blood-brain barrier penetration (EUDA [Ref 29]; Milella et al. 2023 [Ref 1]).

**Active metabolites and receptor profile:**
- **6-MAM:** Mu-opioid receptor (MOR) agonist with higher potency than morphine; also active at delta (DOR) and kappa (KOR) receptors
- **Morphine:** Full MOR agonist; Ki at human MOR falls in the 1–100 nM range (Volpe et al. 2011 [Ref 32])
- **M6G:** Active MOR agonist; contributes to sustained analgesic/euphoric effects

No direct radioligand binding Ki values for heroin itself were found in published literature; the IUPHAR/BPS Guide to Pharmacology confirms heroin acts via deacetylation rather than direct high-affinity receptor binding. The seed data listing heroin as a "Kappa-opioid receptor agonist" requires clarification: heroin's kappa activity is indirect (via metabolites) and secondary to its mu activity. **FLAG: Pharmacological class in DB lists "Kappa-opioid receptor agonist" as a primary class — literature supports heroin's effects are primarily MOR-mediated through 6-MAM and morphine; KOR agonism is not a distinguishing feature.**

### Pharmacokinetics

**Blood-brain barrier penetration:**
Following injection, diamorphine crosses the blood-brain barrier within approximately **20 seconds**, with almost **70% of the dose reaching the brain** (EUDA [Ref 29]).

**Plasma kinetics (IV route):**
- **Heroin half-life in plasma:** highly concentration-dependent; **1.2–1.7 minutes** at concentrations ≥25 μM, increasing to approximately **20 minutes** at 1 μM concentrations (Bogen et al. 2023 [Ref 2])
- **Tmax heroin (IV):** 1.1–2.8 minutes
- **Tmax 6-MAM (IV):** 0.7–2.7 minutes
- At concentrations attainable shortly after IV injection, ~70% transforms to 6-MAM within 3 minutes (Bogen et al. 2023 [Ref 2])
- Blood enzymes play a more important role in rapid heroin metabolism than previously assumed (Bogen et al. 2023 [Ref 2])

**Intranasal bioavailability:**
Estimated relative bioavailability of intranasal diamorphine: approximately **52%** compared with intramuscular administration (Cai et al. 2025 [Ref — from PK modeling search]; Guessoum et al. 2025 [Ref 4]).

**Metabolic pathway:**
Heroin → 6-MAM (rapid, enzymatic deacetylation in blood and brain) → Morphine (slower deacetylation) → M3G + M6G (glucuronidation, primarily hepatic). The cascade is sequential with partially overlapping time-concentration profiles (Milella et al. 2023 [Ref 1]).

**CYP involvement:**
Morphine undergoes glucuronidation (UGT2B7, not CYP-mediated). No major CYP enzyme involvement has been identified for the heroin→6-MAM→morphine pathway.

**Postmortem forensic note:**
6-MAM is detectable in vitreous humor in 100% of confirmed heroin-related deaths; vitreous is the optimal matrix for confirming heroin use postmortem (Maskell et al. 2019 [Ref 6]). Co-present markers of illicit heroin include papaverine, noscapine, and codeine (Maskell et al. 2019 [Ref 6]).

---

## History

### Synthesis and Discovery

Heroin was first synthesized in **1874** by **C.R. Alder Wright**, an English chemist at St. Mary's Hospital Medical School in London, who produced it by boiling anhydrous morphine alkaloid with acetic anhydride for several hours (Siu & Moon 2020 [Ref 11]).

The compound was independently re-synthesized in **1897** by **Felix Hoffmann** at **Bayer AG** in Germany. Bayer pharmacologist **Heinrich Dreser** recognized its potential and launched it commercially in **1898** under the trade name "Heroin" (derived from German *heroisch*, meaning heroic), marketed as a cough suppressant and purportedly non-addictive alternative to morphine (Siu & Moon 2020 [Ref 11]).

### Clinical and Regulatory History

- **1898:** Bayer launches diacetylmorphine commercially as "Heroin"
- **1910s:** Recognition of addiction liability mounts; medical community begins expressing concern
- **1914:** US Harrison Narcotics Tax Act regulates opiates
- **1924:** US Congress passes the Anti-Heroin Act, **banning heroin** entirely including for medical use (Siu & Moon 2020 [Ref 11])
- **1961:** United Nations Single Convention on Narcotic Drugs places heroin in Schedule I (Csete et al. 2016 [Ref 19])
- **1970:** US Controlled Substances Act classifies heroin as Schedule I (no accepted medical use, high abuse potential) (Legal source [Ref 30])
- **1994–present:** Switzerland begins heroin-assisted treatment (HAT) program (PROVE) under research conditions; becomes permanent national program (Gschwend et al. 2004 [Ref 28]; Güttinger et al. 2003 [Ref 27])
- **UK exception:** Diamorphine remains licensed in the UK for medical use (injectable for acute pain, heroin-assisted treatment) as a Class A, Schedule 2 substance (EUDA [Ref 29])

---

## Subjective Effects

No published controlled studies of recreational-dose heroin in healthy non-dependent volunteers could be identified (ethical restrictions prevent such studies). Available data come from:

1. **Supervised injectable treatment studies:** Jolley et al. (2015 [Ref 7]) documented the acute physiological profile in HAT patients. Significant respiratory depression (increased ETCO2) was observed in 8/10 patients at 30 minutes post-injection. Hypoventilation reliably detected by capnography but not by pulse oximetry alone.

2. **NAOMI trial data:** Oviedo-Joekes et al. (2009 [Ref 31]) characterizes patient-reported outcomes across medical/psychiatric status, employment satisfaction, and family/social relations.

3. **Pharmacodynamic modeling:** Morse et al. (2022 [Ref — from PK search]) demonstrate that 6-MAM mediates an early "dopaminergic response" accountable for early euphoria, while morphine formation is responsible for the slower, prolonged analgesic response.

**Published effect domains consistent with the seed data taxonomy:**
- **Euphoria ("rush"):** Rapid-onset intense euphoria following IV injection, attributed to rapid 6-MAM delivery to mesolimbic dopamine circuits; less intense but present with intranasal and smoked routes
- **Analgesia:** Potent pain suppression via MOR agonism; potency 2–3× morphine (EUDA [Ref 29])
- **Sedation:** CNS depression, drowsiness
- **Respiratory depression:** The primary cause of fatal overdose; dose-dependent (Jolley et al. 2015 [Ref 7])
- **Miosis:** Pupil constriction (classic opioid sign)
- **Nausea/vomiting:** Common acute adverse effect
- **Pruritus (itching):** MOR-mediated, particularly after IV administration
- **Constipation:** GI motility suppression
- **Euphoria/anxiety suppression:** Anxiolytic effect via MOR activation

**Route-dependent intensity:** IV produces the most intense, rapid rush (onset ~seconds); insufflated onset 10–60 seconds per seed data; smoked onset 5–10 seconds. Intranasal bioavailability ~52% vs. IM.

---

## Safety & Toxicity

### Acute Toxicity

**Animal LD50 data:**
- **Heroin HCl in mice (subcutaneous):** LD50 = 190.5 mg/kg (95% CI; Brands et al. 1976 [Ref 15])
- **Comparative risk benchmark dose (human relevance):** Heroin's benchmark dose is **2 mg/kg bodyweight** — the lowest of all drugs studied in a comparative MOE analysis. This places heroin in the "high risk" category (MOE <10) for individual exposure, alongside alcohol and nicotine (Lachenmeier & Rehm 2015 [Ref 16]).

**FLAG: The acute LD50 in mice (190.5 mg/kg SC) represents an animal value. Human lethal dose data is not available from controlled studies — only from forensic case analyses. The seed data lists "Acute: high; Chronic: high" toxicity without source. This is consistent with published risk assessments but should be noted as inferred.**

### Overdose Mechanism

The primary mechanism of heroin overdose is **respiratory depression** via MOR-mediated reduction of respiratory drive. Death results from hypoxia, hypercapnia, and respiratory arrest. Significant acute respiratory depression is commonly induced by opioids used in addiction treatment; hypoventilation is reliably detected by capnography (elevated ETCO2) but not by SpO2 alone in early stages (Jolley et al. 2015 [Ref 7]).

**Opioid overdose is the primary cause of mortality** in heroin users. Mortality out-of-treatment: 36.1 per 1000 person-years (all-cause); overdose mortality: 12.7 per 1000 person-years (Sordo et al. 2017 [Ref 17]). Globally, opioid overdose accounts for >125,000 deaths annually worldwide; US recorded >100,000 opioid-related deaths in 2022 (Strang et al. 2025 [Ref 36]).

**Heroin is associated with more accidental overdoses and fatal poisonings than any other scheduled substance** (EUDA [Ref 29]).

### Tolerance Reduction as Overdose Risk

A particularly critical period: **post-prison release** or post-abstinence re-use. Tolerance drops rapidly during abstinence, and resuming at prior doses causes overdose. Heroin overdose deaths increased >7-fold in the first fortnight after prison release (Strang et al. 2013 [Ref — from MMWR search, N-ALIVE trial PMID 23633090]).

### Chronic Toxicity

**Neurological:**
- **Toxic leukoencephalopathy ("chasing the dragon" syndrome):** Rare but severe, characterized by progressive white matter damage and symmetrical T2/FLAIR hyperintensities on brain MRI. Classically associated with heroin inhalation (pyrolysis) but also reported with injected and insufflated routes (Cheng et al. 2019 [Ref 38]; Puri et al. 2025 [Ref 37]). Prognosis variable — can range from recovery to death. Infratentorial structures may be spared in non-inhaled forms.

**Infectious complications (injection-associated):**
- Infective endocarditis (bacterial/fungal): Louria et al. 1967 landmark series documented right-sided endocarditis, Staphylococcus aureus, Candida species (Louria et al. 1967 [Ref 8])
- HIV and Hepatitis C transmission via needle sharing; syringe sharing is the primary driver of HCV/HIV in PWID (Palmateer et al. 2022 [Ref 23])
- Septicemia, skin and soft tissue abscesses, tetanus, malaria (shared needle transmission; Louria et al. 1967 [Ref 8])

**Pulmonary:**
- Non-cardiogenic pulmonary edema (acute heroin overdose)
- Aspiration pneumonia
- Septic emboli from endocarditis
- Granulomatous pulmonary disease (talc from adulterants, cotton fiber emboli)

**Obstetric and neonatal:**
- Heroin crosses the placenta; pregnant opioid-dependent women experience **6-fold increase in maternal obstetric complications** (low birth weight, toxaemia, third-trimester bleeding, malpresentation, puerperal morbidity, fetal distress, meconium aspiration)
- Neonatal complications include opioid withdrawal syndrome (NOWS/NAS), postnatal growth deficiency, microcephaly, neurobehavioural problems, increased neonatal mortality, and **74-fold increase in sudden infant death syndrome (SIDS)** (Minozzi et al. 2020 [Ref 45])
- Long-term neurodevelopmental sequelae: decreased cognition, psychomotor performance, language deficits in childhood (Lee et al. 2023 [Ref 47])

**Contemporary adulterant hazards:**
In North America, illicit heroin has been largely **displaced by illicitly manufactured fentanyl** in the drug supply. Fentanyl was detected in 99.2% of opioid-positive paraphernalia samples (Maryland surveillance 2021–2022), with **~80% of fentanyl-positive samples also testing positive for xylazine**, a veterinary alpha-2 adrenergic agonist. Xylazine combined with opioids increases risk of fatal respiratory depression and causes severe soft tissue wounds/necrotic ulcers not reversed by naloxone (Russell et al. 2023 [Ref 43]).

---

## Harm Reduction

### Naloxone (Opioid Antagonist Reversal)

Naloxone is a competitive opioid receptor antagonist that reverses heroin-induced respiratory depression. From 1996–June 2014, US programs distributed naloxone to 152,283 laypersons and received reports of 26,463 overdose reversals (Wheeler et al. 2015 [Ref 21]).

**N-ALIVE trial:** A UK RCT beginning 2012 investigated take-home emergency naloxone for prisoners on release — a population with >7-fold elevated overdose death risk in the first fortnight post-release (Strang et al. 2013 [PMID 23633090]).

**Limitation:** Naloxone does NOT reverse xylazine effects. When xylazine is co-present (increasingly common), naloxone reverses the opioid component but xylazine-induced sedation persists; wound care and supportive management become critical.

### Harm Reduction Strategies (Evidence-Based)

1. **Syringe service programs (SSPs/NSPs):** Reduce HIV and HCV transmission via equipment sharing; evidence base systematic review through 2020 (Palmateer et al. 2022 [Ref 23])
2. **Supervised injection facilities (SIFs):** Provide sterile injecting environment with clinical supervision; documented in Sydney and Vancouver; no overdose deaths recorded on-site
3. **Drug checking services:** Fentanyl test strips and laboratory analysis enable users to detect adulterants; pilot data from Vancouver (2018) and Maryland (2021–2022) (Russell et al. 2023 [Ref 43])
4. **Opioid agonist therapy (OAT/OST):** Methadone and buprenorphine maintenance substantially reduce mortality (all-cause mortality rate 11.3 vs. 36.1 per 1000 person-years in vs. out of treatment; Sordo et al. 2017 [Ref 17])
5. **Heroin-assisted treatment (HAT):** Supervised injectable diamorphine for treatment-refractory patients (see Clinical Trials section)

Full review of harm reduction ethics and clinical rationale: Vearrier 2019 [Ref 22]; Macias-Konstantopoulos et al. 2021 [Ref 20].

---

## Tolerance & Dependence

### Tolerance

Tolerance develops with repeated use via multiple mechanisms including:
- **Mu opioid receptor desensitization:** Chronic heroin self-administration desensitizes MOR-activated G-proteins in specific brain regions including periaqueductal gray, locus coeruleus, lateral parabrachial nucleus, nucleus tractus solitarius, thalamus, and amygdala (Sim-Selley et al. 2000 [Ref 26])
- **Receptor uncoupling and internalization** (signal transduction adaptations)
- **Functional antagonism** via upregulated adenylyl cyclase, NOS, and NMDA receptor activation (Raith & Hochhaus 2004 [PMID 15124977])

Tolerance is cross-tolerant to all opioid-class drugs (mu agonists).

**Seed data tolerance parameters (built-in tolerance data):**
- Buildup: develops with prolonged and repeated use — consistent with literature
- Half-life of tolerance: 5 days — no primary source found to confirm this specific value; **FLAG for editorial review**
- Full reset: 1.5 weeks — no primary source found; **FLAG for editorial review**
- Cross-tolerances: opioids — confirmed

### Physical Dependence and Withdrawal

Physical dependence develops rapidly with regular use. Withdrawal syndrome upon cessation includes:
- Anxiety, restlessness, irritability, insomnia
- Muscle aches, bone pain, cramps
- Nausea, vomiting, diarrhea
- Yawning, lacrimation, rhinorrhoea
- Piloerection, diaphoresis
- Tachycardia, hypertension

**Timeline:** Withdrawal typically begins within 6–24 hours of last use, peaks at 36–72 hours, with acute symptoms resolving over 5–10 days; protracted abstinence syndrome may persist for weeks.

**Dependence liability:** High — heroin has among the highest dependence liability of commonly used substances. The characteristic of negative reinforcement (use to avoid withdrawal) substantially drives compulsive use.

**Management of withdrawal:** Buprenorphine is effective for managing opioid withdrawal (Gowing et al. 2017 [Ref 39]). Methadone maintenance is also established. Non-opioid agents (clonidine, lofexidine) may be used in acute care settings (Erstad et al. 2025 [PMID 39657683]).

---

## Interactions

### Dangerous/Lethal Combinations

**CNS depressants — additive/synergistic respiratory depression:**

- **Benzodiazepines (alprazolam, diazepam) — DANGEROUS/LETHAL:** Benzodiazepines are among the most prevalent co-ingested substances in opioid fatalities (Nielsen et al. 2015 [Ref 35]). The combination produces additive or synergistic respiratory depression beyond what either drug produces alone. Concurrent benzodiazepine use is a major independent risk factor for opioid overdose death.

- **Alcohol — LETHAL:** Ethanol is a CNS depressant that additively potentiates opioid-induced respiratory depression and sedation. Frequently involved in heroin overdose deaths.

- **GHB/GBL — LETHAL:** GHB/GBL are GABA-B agonists and CNS depressants; combined with heroin creates high-risk additive respiratory/CNS depression.

- **Ketamine — LETHAL:** Ketamine is an NMDA antagonist with sedative/anesthetic properties; combination with heroin creates high-risk CNS and respiratory depression.

- **Tramadol — LETHAL:** Tramadol has both opioid agonist and serotonin/noradrenaline reuptake inhibitor properties. Combined with opioids, respiratory depression is potentiated; additionally, tramadol lowers seizure threshold (Ripple et al. 2000 [PMID 11111800]). The combination is potentially fatal.

- **Nitrous oxide — UNKNOWN:** No published pharmacokinetic or pharmacodynamic interaction data found. **FLAG: interaction severity listed as "unknown" in seed data; no literature to clarify.**

- **PCP — UNKNOWN:** No published interaction data found. **FLAG: interaction severity listed as "unknown" in seed data; no literature to clarify.**

### Antidote/Reversal

- **Naloxone (low-risk interaction):** Competitive MOR antagonist; reverses heroin-induced respiratory depression. Effective but duration of action shorter than heroin/6-MAM, requiring redosing or infusion. Does NOT reverse xylazine sedation. Mass spectrometric imaging confirms naloxone displaces 6-MAM from brain opioid receptors (Teklezgi et al. 2020 [Ref — PMID 32548443]).

### Contemporary Drug Supply Interaction

The near-displacement of heroin by fentanyl in North America creates a critical practical interaction: users expecting heroin pharmacokinetics (onset/duration) encounter fentanyl's far higher potency (50–100× morphine), increasing overdose risk. When xylazine is co-present, standard naloxone protocols are insufficient.

---

## Legal Status

| Jurisdiction | Classification | Key Provisions |
|---|---|---|
| **United States** | Schedule I (Controlled Substances Act 1970) | No accepted medical use; high abuse potential; possession/distribution federal felony |
| **United Kingdom** | Class A, Schedule 2 (Misuse of Drugs Act 1971) | Schedule 2 permits medical use (licensed as diamorphine); possession max 7 years; trafficking max life imprisonment |
| **European Union** | UN 1961 Single Convention Schedule I | Subject to EU/national control; varies by member state |
| **Canada** | Schedule I (Controlled Drugs and Substances Act 1996) | Max 7 years imprisonment (indictable possession); max life for trafficking |
| **Australia** | Schedule 9 (Prohibited Substance, Standard for Uniform Scheduling of Medicines and Poisons) | Most severe category; possession and supply criminal offences with state-level penalties |
| **Germany** | BtMG (Betäubungsmittelgesetz) Annex I | Unauthorized possession/trafficking criminal offence; small quantity possession may be subject to prosecutorial discretion (1g threshold in some states); penalties up to 5–15 years |
| **Switzerland** | Special exception: licensed for heroin-assisted treatment under federal health authority |

**Sources:** DEA Schedule [Ref 30]; EUDA [Ref 29]; Csete et al. Lancet 2016 [Ref 19]; Australian Health Department; Canadian CDSA; German BtMG [Ref 34]

**International framework:** Heroin is listed in Schedule I of the UN **1961 Single Convention on Narcotic Drugs** (the founding international treaty on drug control), making its production, possession, and trade illegal in all signatory states except under strict medical/scientific authorization (Csete et al. 2016 [Ref 19]).

---

## Clinical Trials

### Heroin-Assisted Treatment (HAT) — Key Trials

**NAOMI Trial (North American Opiate Medication Initiative):**
- Phase III RCT comparing injectable diacetylmorphine (DAM) vs. oral methadone maintenance in chronic treatment-refractory heroin-dependent individuals in Vancouver and Montreal, Canada
- **Design:** N=251 randomized; 115 DAM, 111 methadone; open-label; 12-month treatment phase (Oviedo-Joekes et al. 2009 [Ref 31])
- **Results:** 67.0% of DAM group showed treatment response (reduction in illicit drug use or illegal activity) vs. 47.7% methadone group; 88% vs. 54% retention in treatment; significant improvement in 6/7 evaluated domains for DAM group (Oviedo-Joekes et al. 2009 [Ref 31])
- **NCT:** See Oviedo-Joekes 2009 [Ref 31] and design paper (Oviedo-Joekes et al. 2009 [Ref 13])

**Swiss PROVE Programme:**
- Initiated January 1994; heroin-assisted treatment for severely dependent, treatment-resistant individuals at 8 centres
- **6-year follow-up (n=366):** 46% of living clients still in HAT at follow-up; significant decreases in illicit substance use, illegal income, and improvements in social conditions vs. entry; effects persisted after termination of HAT (Güttinger et al. 2003 [Ref 27])
- Dosing: courses of dose levels analysed by Gschwend et al. 2004 [Ref 28]

**Systematic Review/Meta-analysis of HAT RCTs:**
- Strang et al. 2015 [Ref 24]: Landmark systematic review and meta-analysis of all RCTs of supervised injectable heroin (SIH) for refractory heroin addiction; confirmed efficacy across multiple European (Switzerland, Netherlands, Spain, Germany, Canada, UK) trials

**ClinicalTrials.gov — Active/Relevant Trials:**
- NCT00332228 (COMPLETED, Phase 2): "Behavioral Naltrexone Therapy: A Novel Treatment for Heroin Dependence" — New York State Psychiatric Institute
- NCT02524912: "Methadone Maintenance Outcome Study in Taiwan: 5-year Follow-up" — conditions include heroin dependence
- NCT04003077: "Laser Meridian Massage in Heroin Addicts" — Chang Gung Memorial Hospital

**Current HAT status (2026):** HAT is established as a legal treatment in Switzerland, Netherlands, UK, Germany, Denmark, Belgium, Norway, Canada (limited). US does not permit HAT. No currently recruiting large RCTs identified for diacetylmorphine-specific trials.

---

## Community Feedback Analysis

No community feedback was submitted in Part A2 of the brief.

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## Gaps & Flags

### Verified Data Points with No Primary Source Found

1. **FLAG — Tolerance half-life "5 days" and full reset "1.5 weeks":** These specific tolerance decay values appear in the DB seed data but no primary published study was identified to support them. The figures may derive from community consensus or structural analog inference from opioid tolerance literature. **Recommend editorial review; do not present as established data.**

2. **FLAG — Pharmacological class "Kappa-opioid receptor agonist":** Heroin and its metabolites are primarily MOR agonists. While 6-MAM and morphine have some KOR/DOR activity, classifying heroin as a "kappa-opioid receptor agonist" is potentially misleading. No published Ki measurements for heroin itself at KOR were retrieved. The primary pharmacological class should read: **Mu-opioid receptor agonist (via active metabolites 6-MAM and morphine)**. The KOR designation requires a specific cited source before inclusion.

3. **SMILES string absent in PubChem API response:** The PubChem API tool returned the InChIKey, formula, and IUPAC name but not the SMILES. PubChem page is JavaScript-dependent. The generation agent should obtain SMILES via direct PubChem API (CID 5462328) before populating that field.

4. **Interaction severity for Nitrous oxide (listed "unknown"):** No published pharmacokinetic or pharmacodynamic interaction data for heroin + nitrous oxide was identified. The "unknown" classification in the DB appears appropriate given the absence of published data. No change recommended.

5. **Interaction severity for PCP (listed "unknown"):** No published data found. Same assessment as nitrous.

6. **Dose/duration data (seed data):** No controlled dose-finding studies in humans exist for recreational heroin (ethical restriction). The dose/duration values in the DB likely derive from community consensus (harm reduction organizations, drug user reports). The seed data values are plausible relative to published HAT dosing regimens (NAOMI patients used injectable DAM across a range of doses). **Recommend retaining existing DB values with community consensus sourcing note; flag the absence of primary controlled studies.**

7. **Primary ROA listed as "insufflated":** This is potentially misleading for a substance where intravenous injection carries the highest clinical and public health burden, and where IV use is the route in all clinical HAT trials. Insufflation ("snorting") is certainly practiced but IV is the dominant route in terms of health outcomes and treatment literature. The generation agent may wish to review this with editors.

8. **Contemporary drug supply note:** In North America (US), illicit heroin has been largely displaced by illicitly manufactured fentanyl as of 2021–2022 (fentanyl in 99.2% of opioid-positive samples; Russell et al. 2023 [Ref 43]). Any dose/harm content must acknowledge this context — users seeking heroin in the current North American market are predominantly encountering fentanyl ± xylazine, not traditional heroin.

9. **Toxicity notes in seed data:** "Inferred from pharmacological class — not sourced from literature. Review recommended." — The seed data itself contains this flag. The acute and chronic toxicity ratings of "high" are supported by the literature (Lachenmeier & Rehm 2015 [Ref 16]; Sordo et al. 2017 [Ref 17]; EUDA [Ref 29]), but specific clinical toxicity thresholds in humans are not available from controlled studies.

10. **Existing pharmacology JSONB is empty:** Awaits population from this research; recommended minimum fields: primary target = MOR, primary mechanism = "full agonist (via metabolites 6-MAM and morphine)", potency relative to morphine = "2–3×" (EUDA), half-life = "~3 min plasma (heroin); longer for active metabolites."