# Kratom and 7-Hydroxymitragynine: Metabolism, Pharmacokinetics, Receptor Pharmacology, Related Compounds, and Testing

**Clinical and analytical reference sheet**  
**Prepared for EusomniaMD | August 7, 2026**  
**Scope:** *Mitragyna speciosa* alkaloids, known human metabolites, concentrated 7-hydroxymitragynine (7-OH/7-HMG), mitragynine pseudoindoxyl (MP/MGP), and related semisynthetic opioid derivatives.

> **Evidence convention.** “Human half-life” below means a terminal plasma half-life measured in humans unless otherwise specified. Many metabolites have been identified in human urine but have **no measured human systemic half-life**. For 7-OH, published human half-lives after kratom/mitragynine exposure reflect a compound that is being formed from mitragynine while it is being eliminated. They should not be treated as the direct elimination half-life of purified high-dose 7-OH. Direct human pharmacokinetic studies of purified commercial 7-OH, mitragynine pseudoindoxyl, MGM-15, and MGM-16 remain absent or inadequate as of this review. [1-6]

## Executive summary

The pharmacologically important pathway is **mitragynine (MG) → 7-hydroxymitragynine (7-OH) → mitragynine pseudoindoxyl (MP)**. Human CYP3A4 forms 7-OH from mitragynine; 7-OH is substantially more opioid-active than mitragynine. In human plasma, 7-OH can rearrange to MP, an even more potent μ-opioid receptor ligand. Mitragynine also undergoes extensive O-demethylation, ester hydrolysis/oxidation, reduction, and phase-II glucuronidation/sulfation. The quantitatively prominent urinary metabolites, particularly **9-O-demethylmitragynine (9-hydroxycorynantheidine)** and **16-carboxymitragynine**, appear to be far less opioid-active than 7-OH or MP and are useful primarily as exposure biomarkers. [1-4,7]

Kratom is not a single-drug exposure. Major native alkaloids have different pharmacokinetics and receptor profiles. Mitragynine, speciogynine, paynantheine, speciociliatine, mitraciliatine, and isopaynantheine all circulate in humans after botanical kratom. Some minor native oxindole alkaloids can have unexpectedly high opioid-receptor affinity in vitro. Metabolism of speciogynine and paynantheine also generates **9-O-desmethyl metabolites that are functional 5-HT1A agonists**, creating a plausible non-opioid contribution to the effects of botanical kratom. [5,8,9]

For clinical testing, **dedicated LC-MS/MS or LC-HRMS is the preferred approach**. Routine “opiate” immunoassays should not be assumed to detect kratom alkaloids. Urine is generally the most useful matrix for documenting exposure; blood/plasma is preferable when timing, toxicity, or pharmacokinetic interpretation is important; hair can document remote/chronic exposure but is poorly suited to recent exposure. A positive 7-OH result does **not** prove that a patient ingested a concentrated 7-OH product, because humans form 7-OH from mitragynine. There is currently no validated mitragynine:7-OH ratio that reliably distinguishes botanical kratom exposure from direct commercial 7-OH ingestion. [2,10-15]

---

# 1. Metabolic map

```text
MITRAGYNINE (MG)
│
├── CYP3A4 ───────────────> 7-HYDROXYMITRAGYNINE (7-OH / 7-HMG)
│                              │
│                              └── human plasma rearrangement ──> MITRAGYNINE PSEUDOINDOXYL (MP / MGP)
│
├── CYP2C19 / CYP3A4 / CYP2D6 ─> 9-O-DEMETHYLMITRAGYNINE
│                                  (= 9-hydroxycorynantheidine)
│
├── CYP2D6 / CYP2C19 / CYP2C18 ─> 16-CARBOXYMITRAGYNINE
│                                   (methyl-ester hydrolysis/oxidation pathway)
│
├── CYP2C19 ───────────────> 9-O-DEMETHYL-16-CARBOXYMITRAGYNINE
│
├── C17 O-demethylation / reduction / oxidation
│     ├── 17-O-demethyl-16,17-dihydromitragynine
│     └── 17-carboxy-16,17-dihydromitragynine
│
├── oxidative pathway ─────> 3-DEHYDROMITRAGYNINE (3DM)
│                              [described in metabolic/product-chemistry work;
│                               human toxicokinetics not established]
│
└── phase-II conjugation ──> glucuronides and sulfates of multiple hydroxylated/
                              carboxylated metabolites

SPECIOGYNINE ──> 9-O-desmethylspeciogynine (gambirine) ──> functional 5-HT1A agonism
PAYNANTHEINE ──> 9-O-desmethylpaynantheine (gambireine) ─> functional 5-HT1A agonism

SPECIOCILIATINE, MITRACILIATINE, ISOPAYNANTHEINE
  └── analogous O-demethylation, ester hydrolysis/oxidation, reduction,
      and phase-II conjugation pathways; several metabolites are detectable in human urine.
```

The enzymes above are supported by recombinant CYP and human microsomal work. CYP3A4 is dominant in mitragynine metabolism and is the CYP isoform directly demonstrated to generate 7-OH. 7-OH → MP conversion has been demonstrated strongly in **human plasma in vitro**; its exact quantitative contribution after direct high-dose 7-OH ingestion in living humans has not been established. [1-4]

---

# 2. Core compounds and clinically important metabolites

| Compound | Relationship / formation | Human plasma half-life | Elimination / disposition | Receptor pharmacology most relevant to humans | Likely clinical relevance |
|---|---|---:|---|---|---|
| **Mitragynine (MG)** | Principal native kratom alkaloid; parent of 7-OH and numerous oxidative/demethylated metabolites | **~23 h** in chronic tea users; **median 45.3 h** after standardized kratom tea; up to ~43 h single-dose and ~68 h after repeated dried-leaf dosing in another study. Concentrated-extract studies also show dose- and repeat-dose-dependent terminal phases. [5,6,16] | Extensively metabolized. Only a small fraction is excreted unchanged in urine; one human study measured **0.14% unchanged**. CYP3A4 predominates, with CYP2D6, CYP2C19/2C18 and other pathways contributing. [2,3,16] | hMOR agonism is assay-dependent and generally partial/low-efficacy relative to 7-OH. 2026 human-receptor study: hMOR Ki ~238 nM; cAMP EC50 ~396 nM, Emax ~69%. Weak KOR activity in that system. Older BRET work found MOR partial agonism with KOR/DOR antagonism. [8,17] | Analgesic/opioid effects are partly direct and partly mediated by 7-OH formation. Botanical kratom effects also reflect non-MG alkaloids. Dependence occurs with chronic exposure. |
| **7-Hydroxymitragynine (7-OH, 7-HMG)** | Minor natural alkaloid and **CYP3A4-generated active metabolite of MG**; also manufactured/enriched in modern products | After MG/kratom exposure: median **5.67 h** in tea study; highest mean ~**4.7 h single** and **24.7 h repeated** dried-leaf dosing; 2026 concentrated-extract data show roughly **2-6 h after single doses** with very prolonged/variable apparent terminal values after repeated exposure. **Direct purified-7-OH human t½ is unknown.** [5,6,18] | Further conversion/rearrangement to MP in human plasma; additional oxidative/degradative products are possible. Direct human mass balance after purified 7-OH has not been published. [4] | 2026 hMOR Ki **15.1 nM**, hKOR 113 nM, hDOR 137 nM. cAMP: MOR EC50 **13.6 nM**, KOR 440 nM, DOR 151 nM, with high efficacy in that assay. Older BRET studies found MOR partial agonism and KOR/DOR antagonism. Therefore **efficacy is assay/receptor-reserve dependent**. [8,17] | Potent opioid effects, analgesia, euphoria/sedation, tolerance, dependence, withdrawal, and respiratory-depression/overdose potential. Concentrated products should not be pharmacologically equated with ordinary leaf kratom. |
| **Mitragynine pseudoindoxyl (MP, MGP)** | Rearrangement/oxidation product related to MG; **formed from 7-OH in human plasma in vitro**. Also marketed directly in semisynthetic products. | **Unknown in humans** | Human plasma readily converts 7-OH to MP in vitro. Direct in-vivo human clearance, renal excretion, and mass balance are unknown. [4] | Potent MOR agonist; modern studies describe **MOR agonism with DOR antagonism** and little/no β-arrestin-2 recruitment. Older tissue assays also demonstrated potent μ- and δ-opioid effects. [19,20] | Strong opioid effects. A 2026 clinical case described severe, early-onset opioid-like withdrawal after high-dose intentional MP use. Human PK and dose-response remain poorly characterized. [21] |
| **9-O-Demethylmitragynine (9ODM; 9-hydroxycorynantheidine)** | Major MG O-demethylation product; formed by CYP2C19, CYP3A4, and CYP2D6; highly prevalent in urine | **Unknown** | Detected commonly in urine; further glucuronidated and sulfated. Useful exposure marker. [2,7,11] | Opioid-active but much less compelling than 7-OH/MP. Recent biotransformation work reports lower MOR potency than MG. [7] | Probably contributes little to the intense opioid phenotype of concentrated 7-OH compared with 7-OH/MP; analytically valuable. |
| **16-Carboxymitragynine** | MG methyl-ester hydrolysis/oxidation product; formed by CYP2D6, CYP2C19, CYP2C18 in recombinant systems; can also form chemically under alkaline conditions | **Unknown** | Prominent urinary metabolite; glucuronide detected. [2,7,11,22] | Little meaningful MOR agonism; recent work found **no hMOR agonism up to 100 μM**. [7] | Primarily an elimination/exposure biomarker rather than an important opioid effector. |
| **9-O-Demethyl-16-carboxymitragynine** | Sequential O-demethylation + carboxylation; CYP2C19 supported in recombinant CYP work | **Unknown** | Human urinary sulfate described; parent metabolite used analytically. [2,11] | Clinically meaningful receptor activation not established | Exposure marker. |
| **17-O-Demethyl-16,17-dihydromitragynine** | C17 O-demethylation followed by reduction | **Unknown** | Human urinary phase-I metabolite; glucuronide also reported. [7,23] | Not established | Exposure marker; clinical pharmacology unknown. |
| **17-Carboxy-16,17-dihydromitragynine** | C17 demethylation/oxidation pathway | **Unknown** | Detected in human urine. [23] | Not established | Exposure marker. |
| **3-Dehydromitragynine (3DM)** | Oxidative MG derivative; also appears as an oxidation/degradation product in processed 7-OH products | **Unknown** | Human toxicokinetics unknown. Formation has been described in oxidative metabolism/product studies. [24] | MOR Ki reported around **34 nM** with partial MOR agonism in preclinical functional work, but pharmacology is not equivalent to clinical exposure. [24] | Preclinical work raises a toxicity signal that may not be entirely opioid-receptor mediated. Human clinical significance remains unknown. Do not infer human lethality from animal dose studies. |
| **9-O-Desmethylspeciogynine (gambirine)** | Active O-demethylated metabolite of speciogynine | **Unknown** | Human systemic PK not established | **5-HT1A agonist**, EC50 ~**838 nM**, near-full efficacy in tested cAMP system; partial inverse agonism at 5-HT2B rather than agonism. [9] | Plausible contributor to mood/anxiolytic/antinociceptive features of botanical kratom; magnitude in humans unknown. |
| **9-O-Desmethylpaynantheine (gambireine)** | Active O-demethylated metabolite of paynantheine | **Unknown** | Human systemic PK not established | **5-HT1A agonist**, EC50 ~**865 nM**, near-full efficacy in tested system; partial inverse agonism at 5-HT2B. [9] | Same caveat as above. Supports a mechanistic basis for non-opioid effects of whole-plant kratom, not evidence that purified 7-OH is serotonergic. |

## Interpretation of the 7-OH half-life problem

The numbers above need unusually careful wording. Human trials that report a 7-OH half-life generally administered **kratom, mitragynine-containing leaf, or mitragynine-rich extract**, not purified 7-OH. 7-OH is therefore being generated from a longer-lived precursor while it is being cleared. Under repeated dosing, the apparent terminal phase may become **formation-limited** and very variable. The safest publication language is:

> **“After botanical kratom or mitragynine-rich products, circulating 7-OH typically shows a short early disposition phase, with reported single-dose terminal estimates around 2-6 hours in several studies. Longer and highly variable apparent half-lives occur after repeated mitragynine exposure. The elimination half-life of directly administered, purified high-dose 7-OH in humans has not been established.”** [5,6,18]

That distinction is clinically important when reasoning about withdrawal and buprenorphine timing.

---

# 3. Major native kratom alkaloids with measured human pharmacokinetics

A standardized kratom-tea study provides the best comparative human PK dataset for multiple alkaloids. [5]

| Native alkaloid | Median human terminal t½ (range) after kratom tea | Relevant receptor findings | Clinical interpretation |
|---|---:|---|---|
| **Mitragynine** | **45.3 h** (31.9-50.2) | MOR agonist; assay-dependent partial efficacy; weaker KOR/DOR effects | Dominant systemic alkaloid and metabolic precursor of 7-OH |
| **Speciogynine** | **23.5 h** (16.1-28.3) | Weak/low-efficacy MOR activity; parent binds serotonin receptors but 5-HT1A functional agonism appears to arise mainly after O-demethylation | May contribute to non-opioid effects through metabolite formation |
| **Paynantheine** | **27.0 h** (17.7-30.8) | Low-efficacy MOR activity; serotonergic metabolite pathway | Similar caveat |
| **Speciociliatine** | **12.3 h** (10.4-21.1) | High/moderate MOR affinity relative to several native alkaloids (2026 hMOR Ki ~49 nM); partial MOR agonism; KOR activity in some assays | Could materially contribute to whole-plant opioid pharmacology despite lower abundance |
| **Mitraciliatine** | **17.8 h** (11.2-24.7) | 2026 study: weak MOR antagonism in GTPγS but **KOR agonism** (EC50 ~654 nM, high efficacy) | Clinically meaningful contribution uncertain because exposure is lower than MG |
| **Isopaynantheine** | **14.4 h** (11.8-20.9) | Weak MOR antagonism; **KOR agonism** (EC50 ~536 nM, high efficacy) in 2026 GTPγS work | Same caveat |
| **7-OH** | **5.67 h** (5.03-6.52) in this tea study | Potent MOR agonism; KOR/DOR behavior assay-dependent | Formed metabolically; not equivalent to direct concentrated 7-OH dosing |

The 3S alkaloids (MG, speciogynine, paynantheine) generally showed longer terminal half-lives than the 3R diastereomers (speciociliatine, mitraciliatine, isopaynantheine), likely reflecting differences in distribution, metabolism, protein binding, and clearance. [5]

---

# 4. Additional characterized human urinary metabolites

The following compounds have been described in **human urine after kratom exposure** or in human biomarker studies. For most, systemic plasma exposure, receptor activity, and human terminal half-life are unknown. Their principal present value is analytical rather than therapeutic/toxicologic. [2,11,23,25,26]

| Parent alkaloid | Phase-I metabolites documented in human urine | Phase-II products documented/reported in human urine | Pharmacologic status |
|---|---|---|---|
| **Mitragynine** | 9-O-demethyl-MG; 16-carboxy-MG; 9-O-demethyl-16-carboxy-MG; 17-O-demethyl-16,17-dihydro-MG; 17-carboxy-16,17-dihydro-MG; additional oxidation/reduction products described | Glucuronides of 9-O-demethyl-MG, 16-carboxy-MG, 17-O-demethyl-16,17-dihydro-MG; sulfates of 9-O-demethyl-MG, 9-O-demethyl-16-carboxy-MG, and 9,17-O-bisdemethyl-16,17-dihydro-MG | 9ODM retains opioid activity but is weaker than the 7-OH/MP pathway; 16-carboxy-MG is largely inactive at MOR; most others uncharacterized |
| **Paynantheine (PAY)** | 9-O-demethyl-PAY; 16-carboxy-PAY; 17-carboxy-16,17-dihydro-PAY | Glucuronides of 9-O-demethyl-PAY and 16-carboxy-PAY; sulfate of 9-O-demethyl-PAY | 9-O-desmethyl-PAY has functional 5-HT1A agonism; most other metabolites uncharacterized |
| **Speciogynine (SG)** | 9-O-demethyl-SG; 16-carboxy-SG; 17-carboxy-16,17-dihydro-SG | Glucuronides of 9-O-demethyl-SG and 16-carboxy-SG; sulfate of 9-O-demethyl-SG | 9-O-desmethyl-SG has functional 5-HT1A agonism; most other metabolites uncharacterized |
| **Speciociliatine (SC)** | 9-O-demethyl-SC; 16-carboxy-SC; 9-O-demethyl-16-carboxy-SC; additional mono-oxidation/O-demethylation products | Glucuronides including 9-O-demethyl-SC and 16-carboxy-SC; additional conjugated metabolites reported | Parent has MOR activity; clinical pharmacology of metabolites largely unknown |
| **Mitraciliatine (MC)** | 9-O-demethyl-MC detected among human urinary products | 9-O-demethyl-MC conjugate(s) reported | Parent shows KOR-biased functional profile in recent receptor work; metabolites inadequately characterized |
| **Isopaynantheine (ISO-PAY)** | 9-O-demethyl-ISO-PAY; 17-carboxy-16,17-dihydro-ISO-PAY reported at low abundance | Limited human phase-II information due low native abundance | Parent can act as KOR agonist in vitro; metabolite significance unknown |

**Important limitation:** “Detected in human urine” does not mean “circulates at pharmacologically important concentrations.” Many urinary metabolites are endpoints of clearance and may have little or no CNS exposure.

---

# 5. Receptor activation and modulation map

## 5.1 Opioid receptors

### 7-Hydroxymitragynine

The 2026 systematic study of human opioid receptors found 7-OH to be the only tested kratom alkaloid with substantial functional activity at all three classical opioid receptor subtypes: [8]

| Target | Binding affinity | Functional cAMP result in 2026 study | Interpretation |
|---|---:|---:|---|
| **μ-opioid receptor (MOR)** | Ki **15.1 ± 3.7 nM** | EC50 **13.6 ± 0.9 nM**, Emax ~85.9% of reference agonist | Dominant clinically relevant target |
| **κ-opioid receptor (KOR)** | Ki **113 ± 37 nM** | EC50 **440.1 ± 7.0 nM**, high efficacy | Secondary, lower-potency activity; clinical contribution uncertain |
| **δ-opioid receptor (DOR)** | Ki **137.3 ± 21.3 nM** | EC50 **150.8 ± 22.6 nM**, high efficacy | Secondary activity; clinical contribution uncertain |

Earlier human-receptor BRET studies characterized 7-OH as a **partial MOR agonist with competitive KOR/DOR antagonism** and strong G-protein bias. [17] These results are not necessarily contradictory: GPCR efficacy can change with receptor reserve, cell system, and signaling readout. For publication, avoid categorical statements that 7-OH is either universally a “full agonist” or universally a “weak partial agonist.” A defensible formulation is:

> **7-OH is a high-potency MOR agonist with assay-dependent intrinsic efficacy and pronounced G-protein signaling; activity at KOR and DOR is lower-potency and assay-dependent.**

### Mitragynine

Mitragynine is a less potent MOR agonist than 7-OH. The 2026 human-receptor study found hMOR Ki ~238 nM and cAMP agonist EC50 ~396 nM with ~69% efficacy, while older BRET work reported lower efficacy and KOR/DOR antagonism. [8,17] Its clinical opioid effect is therefore a combination of **direct MG pharmacology plus metabolic formation of 7-OH**. [1]

### Mitragynine pseudoindoxyl

MP is a potent MOR agonist. Modern mechanistic work describes **MOR agonism plus DOR antagonism**, with little β-arrestin-2 recruitment in the studied systems. [19] Older isolated-tissue studies also found potent μ- and δ-opioid effects. [20] These differences again illustrate assay dependence.

### Other native alkaloids

Recent human-receptor work expands the relevant target map: [8]

- **Speciociliatine:** hMOR Ki ~49 nM; partial MOR agonist; KOR binding/activity at lower potency.
- **Mitraciliatine:** hMOR Ki ~226 nM and hKOR Ki ~108 nM; weak MOR antagonist in GTPγS but moderate/high-efficacy KOR agonist (EC50 ~654 nM).
- **Isopaynantheine:** hMOR Ki ~262 nM and hKOR Ki ~130 nM; weak MOR antagonist and KOR agonist (EC50 ~536 nM).
- **Mitragynine-N(4)-oxide:** negligible hMOR binding in the 2026 study but hKOR Ki ~145 nM; full-efficacy KOR agonism in cAMP assay (EC50 ~120 nM).
- **Corynoxine A:** very high hMOR affinity (Ki ~5.4 nM) and potent MOR agonism (cAMP EC50 ~34 nM in that system). Human exposure is poorly characterized, so high in-vitro potency does not establish major clinical contribution.
- **Corynoxine B** and **isospeciofoline:** moderate MOR affinity and agonist activity in vitro.
- **Speciophylline (uncarine D):** no direct orthosteric agonism, but **positive allosteric modulation of MOR**, potentiating met-enkephalin signaling (PAM EC50 ~27 μM). This is mechanistically interesting but not evidence of major clinical effect at ordinary exposure.

## 5.2 Serotonin receptors

The best-established non-opioid activation pathway involves metabolites of speciogynine and paynantheine: [9]

- **9-O-desmethylspeciogynine:** full-efficacy **5-HT1A agonist**, EC50 ~838 nM.
- **9-O-desmethylpaynantheine:** full-efficacy **5-HT1A agonist**, EC50 ~865 nM.
- These metabolites did **not** act as 5-HT2B agonists; rather, they showed inverse-agonist behavior in the tested system.

This is a plausible mechanistic contributor to mood, anxiolytic-like, and non-opioid antinociceptive effects of **whole-plant kratom**. It should not be transferred automatically to purified 7-OH.

## 5.3 Adrenergic and other targets

Kratom literature contains numerous reported binding interactions, but binding should not be confused with receptor activation. Mitragynine has demonstrated low-potency α1A-adrenergic partial agonism in recent functional work, while direct α2A agonism is not supported by contemporary receptor assays. Dopamine, muscarinic, cannabinoid, and several serotonin-receptor interactions have been reported at the binding, computational, or indirect physiological level, but do not currently justify listing them as established clinically meaningful agonist targets of purified 7-OH. [27]

---

# 6. Related semisynthetic and oxidative compounds

These compounds are particularly important because the modern retail market increasingly contains substances that are **not equivalent to botanical kratom**.

| Compound | Relationship to kratom/7-OH | Receptor pharmacology | Human PK / elimination | Clinical status |
|---|---|---|---|---|
| **Mitragynine pseudoindoxyl (MP/MGP)** | Rearrangement product of 7-OH; can form in human plasma; also sold directly | Potent MOR agonist; DOR antagonist in modern studies | **Unknown** | Direct-use severe dependence/withdrawal now reported; no controlled human PK study [4,19,21] |
| **MGM-15** | Semisynthetic derivative developed from 7-OH; reductive/saturation modification of the 7-OH scaffold | Higher hMOR/hDOR affinity than 7-OH reported in 2025 commercial-product study; μ/δ agonist lineage | **Unknown** | Commercial “research chemical” tablets documented; no established human safety, dose, or PK [28] |
| **MGM-16** | Semisynthetic 7-OH derivative | **Dual μ/δ full agonist**; Ki ~**2.1 nM MOR** and **7.0 nM DOR** in foundational work | **Unknown** | Extremely potent in animal antinociception models; human clinical exposure/safety not established [29] |
| **3-Dehydromitragynine (3DM)** | Oxidative/degradation product related to MG and processed 7-OH chemistry | Partial MOR agonist in preclinical work (Ki ~34 nM reported) | **Unknown** | Animal toxicity signal; human significance unknown [24] |

**Clinical implication:** if a patient says “7-OH,” the actual exposure can be chemically heterogeneous. Product analysis may reveal 7-OH, MP, 3DM, MGM-series derivatives, native alkaloids, oxidation products, or mislabeled concentrations. Product identity should be treated as an empirical question when the answer matters clinically or legally. [14,30]

---

# 7. Elimination and renal excretion

Mitragynine and the major native alkaloids are cleared predominantly through **metabolism rather than unchanged renal excretion**. In chronic human tea users, unchanged mitragynine accounted for approximately **0.14%** of dose in urine. [16] The standardized tea PK study similarly found low unchanged urinary fractions for the 3S alkaloids, with somewhat greater unchanged renal recovery of some 3R diastereomers. [5]

For most metabolites, the principal evidence for “elimination” is their **presence in urine**, frequently after glucuronidation or sulfation. Human fecal mass-balance studies, biliary-clearance studies, and complete recovery studies are lacking. Consequently, a publication should avoid percentages for total renal versus fecal elimination beyond what has actually been measured.

7-OH and MP deserve special caution. There is no published human mass-balance study after direct high-dose purified 7-OH, and no validated human elimination study for directly ingested MP. [4-6]

---

# 8. Clinical and forensic testing guidelines

## 8.1 What to order

**Preferred definitive methods:**

1. **Urine LC-MS/MS or LC-HRMS** when the primary question is whether kratom/7-OH-related exposure occurred.
2. **Blood or plasma LC-MS/MS** when recent exposure, intoxication, quantitative concentration, or pharmacokinetic interpretation matters.
3. **Product analysis** when determining whether a patient ingested botanical kratom, concentrated 7-OH, MP, or another semisynthetic product is important.
4. **Hair LC-MS/MS** for historical/chronic exposure questions, with the usual limitations of hair toxicology and much poorer utility for recent exposure. [10,12-15]

Do **not** rely on a routine hospital “opiate” immunoassay to rule exposure in or out. Dedicated mitragynine immunoassays exist experimentally/commercially, but they cross-react with multiple related kratom alkaloids and metabolites and therefore behave as **class-exposure screens**, not precise compound identification. [31]

## 8.2 Recommended urine analyte panel

For a clinically useful **kratom/7-OH exposure panel**, request or develop LC-MS/MS/LC-HRMS coverage for at least:

- mitragynine
- 7-hydroxymitragynine
- 9-O-demethylmitragynine / 9-hydroxycorynantheidine
- 16-carboxymitragynine
- speciociliatine
- speciogynine
- paynantheine
- mitraciliatine, when the laboratory can resolve it

If the history specifically involves a modern concentrated/semisynthetic product, additionally seek:

- mitragynine pseudoindoxyl
- 3-dehydromitragynine
- MGM-15 and MGM-16 when analytically available
- untargeted or expanded LC-HRMS screening when product adulteration is suspected.

## 8.3 Interpretation rules

### A positive 7-OH result does not prove direct 7-OH ingestion

Humans generate 7-OH from mitragynine through CYP3A4. Therefore, **7-OH in blood or urine is compatible with ordinary mitragynine/kratom exposure**. [1,2]

At present there is **no validated universal MG:7-OH concentration ratio** that can distinguish direct concentrated 7-OH ingestion from endogenous formation after botanical kratom. Ratios are affected by dose, product chemistry, time since ingestion, repeated dosing, CYP activity, specimen matrix, and analytical method. When source attribution matters, retain and test the product itself.

### Separate diastereomers chromatographically

Mitragynine, speciogynine, speciociliatine, and mitraciliatine are stereoisomeric/diastereomeric compounds with overlapping mass transitions. Routine HRMS without adequate chromatographic resolution can misidentify or overquantify mitragynine. A validated method should resolve these analytes before assigning a quantitative MG concentration. [12,13]

### Do not assume hydrolysis improves urine detection

In a biomarker study, **speciociliatine and speciogynine frequently exceeded mitragynine in unhydrolyzed urine**, 9-O-demethylmitragynine was detected in 75% of cases, and 7-OH in 63%. Chemical hydrolysis caused degradation; enzymatic hydrolysis materially increased 16-carboxymitragynine but provided little additional yield for many other targets. For most exposure confirmation, unhydrolyzed urine already contains abundant markers. [11]

## 8.4 Specimen stability

7-OH is analytically less stable than mitragynine. In a postmortem matrix study stored at **4°C**, mitragynine remained within accepted stability limits for approximately 30 days whereas 7-OH remained so for about 7 days, with substantial 7-OH loss by 60 days. Methanolic preparations were stable for at least 3 months at −20°C in that study. [14]

These forensic data should not be converted into a universal clinical-laboratory rule. The practical recommendation is:

> **If quantitative 7-OH matters, process promptly and freeze specimens under the receiving laboratory's validated conditions rather than leaving them refrigerated for prolonged periods.**

Modern clinical PK studies have successfully used validated low-temperature frozen storage for MG/7-OH plasma analysis. [6,18]

## 8.5 Detection windows

There is **no validated universal detection window for purified high-dose 7-OH or MP**. Detection depends on dose, chronicity, specimen type, assay sensitivity, renal/hepatic function, product composition, and whether the laboratory measures parent compounds only or metabolites as well.

A defensible public-facing statement is:

- **Urine:** generally the best matrix for demonstrating prior kratom-family exposure because MG, diastereomers, and multiple metabolites are excreted and can remain analytically detectable after plasma concentrations have fallen.
- **Blood/plasma:** better for recent exposure and quantitative toxicology, but interpret 7-OH carefully because it can be both an ingested drug and an MG metabolite.
- **Hair:** can support chronic/remote MG exposure; one validated method reported LODs of **2 pg/mg for MG** and **20 pg/mg for 7-OH**, but 7-OH was not detected in the hair of the studied chronic kratom consumer. [15]

Do not publish a simple “7-OH is detectable for X days” claim unless a specific assay and population are named.

---

# 9. Clinical-effect matrix

| Compound / pathway | Best-supported effects | What should **not** be overstated |
|---|---|---|
| **Mitragynine** | Opioid-like analgesia/euphoria/sedation at relevant exposure, with more complex whole-plant stimulant/autonomic effects; dependence with chronic use; precursor to 7-OH | Do not attribute every botanical kratom effect to MOR or to MG alone |
| **7-OH** | Potent opioid effects, analgesia, sedation/euphoria, tolerance/dependence, opioid-like withdrawal, respiratory-depression/overdose risk | “Partial agonist” does not mean clinically mild; do not state a fixed morphine-equivalent potency in humans based on animal models |
| **MP** | Potent MOR-mediated opioid effects; severe opioid-like dependence/withdrawal now clinically reported | Human potency, duration, half-life, and overdose incidence are not established |
| **9ODM / 16-carboxy-MG** | Primarily metabolic/exposure markers; 9ODM has some opioid activity | Do not treat major urinary abundance as evidence of major CNS pharmacologic contribution |
| **9-O-desmethyl-SG / 9-O-desmethyl-PAY** | 5-HT1A agonism in functional assays; plausible mood/antinociceptive contribution | Human clinical magnitude unknown; not evidence that isolated 7-OH has an antidepressant mechanism |
| **MGM-15 / MGM-16** | High-affinity semisynthetic opioid-receptor pharmacology, especially μ/δ | No established safe human dose, half-life, or treatment algorithm |
| **3DM** | MOR activity plus preclinical non-opioid toxicity signal | Human toxic dose and clinical syndrome unknown |

---

# 10. Practical conclusions for clinicians

**1. Do not equate botanical kratom with concentrated 7-OH.** The former is a multi-alkaloid exposure dominated by MG; the latter can deliver a much more direct high-potency opioid exposure.

**2. Treat 7-OH as both a drug and a metabolite.** This is the central analytical complication. A patient can test positive for 7-OH without having purchased “7-OH.”

**3. Do not infer withdrawal timing from mitragynine's long half-life alone.** Dependence on direct 7-OH may be driven by a substantially shorter effective exposure than botanical MG, while repeated dosing and metabolite formation complicate terminal PK.

**4. Use definitive mass spectrometry when the answer matters.** Routine toxicology panels are not sufficient for source attribution, and even LC-MS methods need chromatographic separation of stereoisomers and orthogonal confirmation for 7-OH/MP in complex products.

**5. Preserve the product.** In 2026, the label is not a reliable substitute for analytical chemistry. If management, public-health reporting, or legal interpretation depends on what was consumed, the tablet/gummy/film/powder itself may be the highest-value specimen.

**6. Be explicit about unknowns.** The absence of a direct purified-7-OH human PK study means that precise withdrawal timing, exact buprenorphine timing, and direct-dose detection windows remain clinical judgments informed by emerging case data rather than validated constants.

---

# 11. Key remaining evidence gaps

The following remain important unanswered questions as of August 2026:

- Direct human pharmacokinetics, bioavailability, distribution, and terminal elimination half-life of **purified high-dose 7-OH**.
- Direct human PK and mass balance of **mitragynine pseudoindoxyl**.
- Human PK/toxicology of **MGM-15 and MGM-16**.
- Quantitative in-vivo fraction of directly ingested 7-OH converted to MP in humans.
- Human toxicokinetics and clinical significance of **3-dehydromitragynine**.
- Receptor occupancy and relative contribution of MOR, KOR, DOR, and non-opioid targets at real-world commercial doses.
- A validated analyte ratio or biomarker signature distinguishing botanical MG exposure from direct 7-OH ingestion.
- Validated detection windows for high-dose purified 7-OH and MP in urine, blood, oral fluid, and hair.
- Prospective pharmacokinetic/pharmacodynamic studies in patients with severe dependence and high-frequency redosing.
- Standardized clinical laboratory panels capable of distinguishing MG, its diastereomers, 7-OH, MP, and emerging semisynthetic derivatives.

---

# References

1. Kruegel AC, Uprety R, Grinnell SG, et al. **7-Hydroxymitragynine Is an Active Metabolite of Mitragynine and a Key Mediator of Its Analgesic Effects.** *ACS Cent Sci.* 2019;5(6):992-1001. doi:10.1021/acscentsci.9b00141. [PubMed](https://pubmed.ncbi.nlm.nih.gov/?term=10.1021%2Facscentsci.9b00141)
2. Basiliere S, Kerrigan S. **CYP450-Mediated Metabolism of Mitragynine and Investigation of Metabolites in Human Urine.** *J Anal Toxicol.* 2020;44(4):301-313. PMID 32008041. [PubMed](https://pubmed.ncbi.nlm.nih.gov/32008041/)
3. Kamble SH, Sharma A, King TI, et al. **Metabolite profiling and identification of enzymes responsible for the metabolism of mitragynine, the major alkaloid of Mitragyna speciosa (kratom).** *Xenobiotica.* 2019. PMID 30547698. [PubMed](https://pubmed.ncbi.nlm.nih.gov/30547698/)
4. Kamble SH, León F, King TI, et al. **Metabolism of a Kratom Alkaloid Metabolite in Human Plasma Increases Its Opioid Potency and Efficacy.** *ACS Pharmacol Transl Sci.* 2020;3(6):1063-1068. doi:10.1021/acsptsci.0c00075. [PubMed](https://pubmed.ncbi.nlm.nih.gov/33344889/)
5. Tanna RS, Nguyen JT, Hadi DL, et al. **Clinical Pharmacokinetic Assessment of Kratom (Mitragyna speciosa), a Botanical Product with Opioid-like Effects, in Healthy Adult Participants.** *Pharmaceutics.* 2022. PMID 35335999. [PubMed](https://pubmed.ncbi.nlm.nih.gov/35335999/)
6. Huestis MA, et al. **Human Mitragynine and 7-Hydroxymitragynine Pharmacokinetics after Single and Multiple Daily Doses of Oral Encapsulated Dried Kratom Leaf Powder.** 2024. PMID 38474495. [PubMed](https://pubmed.ncbi.nlm.nih.gov/38474495/)
7. **Mixtures Biotransformation: Multilayer Molecular Networking of Kratom Liver Metabolites.** *J Nat Prod.* 2026. doi:10.1021/acs.jnatprod.5c01235. [PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC12954754/)
8. Hemby SE, Rangel-Grimaldo M, McIntosh S, et al. **Multifaceted modulation of human opioid receptors by kratom alkaloids: binding affinity, functional selectivity, and allosteric activity.** *Front Pharmacol.* 2026;17:1763551. doi:10.3389/fphar.2026.1763551. [PubMed](https://pubmed.ncbi.nlm.nih.gov/41924140/)
9. Obeng S, Kamble SH, Reeves ME, et al. **Activity of Mitragyna speciosa (“Kratom”) Alkaloids at Serotonin Receptors.** 2021. PMID 34467758. [PubMed](https://pubmed.ncbi.nlm.nih.gov/34467758/)
10. Helander A, Rylski A. **Drug testing for mitragynine and kratom: Analytical challenges and medico-legal considerations.** *Drug Test Anal.* 2023;15. doi:10.1002/dta.3391. [PubMed](https://pubmed.ncbi.nlm.nih.gov/36258649/)
11. Basiliere S, Kerrigan S. **Identification of metabolites and potential biomarkers of kratom in urine.** *J Chromatogr B.* 2020;1140. [NIJ/OJP abstract](https://www.ojp.gov/library/publications/identification-metabolites-and-potential-biomarkers-kratom-urine)
12. Olsen EO, et al. **The Trouble With Kratom: Analytical and Interpretative Issues Involving Mitragynine.** *J Anal Toxicol.* 2019. PMID 31424079. [PubMed](https://pubmed.ncbi.nlm.nih.gov/31424079/)
13. Sheehan D, Li Y, Meckler E, Upton R, Zhang M. **Avoiding False Identification of 7-Hydroxymitragynine in Kratom Products Using a Multicriteria LC-MS Confirmation.** *J Am Soc Mass Spectrom.* 2026;37(5):1303-1312. doi:10.1021/jasms.6c00088. [PubMed](https://pubmed.ncbi.nlm.nih.gov/41989479/)
14. **Postmortem distribution of mitragynine and 7-hydroxymitragynine in 51 cases.** *J Anal Toxicol.* 2025. PMID 39777518. [PubMed](https://pubmed.ncbi.nlm.nih.gov/39777518/)
15. Meier U, Mercer-Chalmers-Bender K, Scheurer E, Dussy F. **Development, validation, and application of an LC-MS/MS method for mitragynine and 7-hydroxymitragynine analysis in hair.** *Drug Test Anal.* 2020;12(2):280-284. doi:10.1002/dta.2746. [PubMed](https://pubmed.ncbi.nlm.nih.gov/31833662/)
16. Trakulsrichai S, Sathirakul K, Auparakkitanon S, et al. **Pharmacokinetics of mitragynine in man.** *Drug Des Devel Ther.* 2015;9:2421-2429. PMID 25995615. [PubMed](https://pubmed.ncbi.nlm.nih.gov/25995615/)
17. Kruegel AC, Gassaway MM, Kapoor A, et al. **Synthetic and Receptor Signaling Explorations of the Mitragyna Alkaloids: Mitragynine as an Atypical Molecular Framework for Opioid Receptor Modulators.** *J Am Chem Soc.* 2016;138:6754-6764. doi:10.1021/jacs.6b00360.
18. Huestis MA, Brett MA, Bothmer J, Henningfield JE, Swift S. **Mitragynine and 7-hydroxy-mitragynine plasma pharmacokinetics in humans after single and 15 multiple oral kratom extract doses.** *J Anal Toxicol.* 2026;50(6):bkag042. doi:10.1093/jat/bkag042. [PubMed](https://pubmed.ncbi.nlm.nih.gov/42266029/)
19. Váradi A, Marrone GF, Palmer TC, et al. **Mitragynine/Corynantheidine Pseudoindoxyls as Opioid Analgesics with Mu Agonism and Delta Antagonism, Which Do Not Recruit β-Arrestin-2.** 2016. PMID 27556704. [PubMed](https://pubmed.ncbi.nlm.nih.gov/27556704/)
20. Yamamoto LT, Horie S, Takayama H, et al. **Opioid receptor agonistic characteristics of mitragynine pseudoindoxyl in comparison with mitragynine derived from Thai medicinal plant Mitragyna speciosa.** 1999;33(1):73-81. doi:10.1016/S0306-3623(98)00265-1. [PubMed](https://pubmed.ncbi.nlm.nih.gov/10428019/)
21. **Severe Early-Onset Withdrawal Following Intentional Use of Mitragynine Pseudoindoxyl: A Case Report and Emerging Clinical Considerations.** 2026. PMID 41982589. [PubMed](https://pubmed.ncbi.nlm.nih.gov/41982589/)
22. Basiliere S, Kerrigan S. **Temperature and pH-Dependent Stability of Mitragyna Alkaloids.** 2020. PMID 31897484. [PubMed](https://pubmed.ncbi.nlm.nih.gov/31897484/)
23. Philipp AA, Wissenbach DK, Zoerntlein SW, Klein ON, Kanogsunthornrat J, Maurer HH. **Studies on the metabolism of mitragynine, the main alkaloid of the herbal drug Kratom, in rat and human urine using LC-linear ion trap MS.** *J Mass Spectrom.* 2009;44(8):1249-1261. doi:10.1002/jms.1607. [PubMed](https://pubmed.ncbi.nlm.nih.gov/19536806/)
24. Chakraborty S, et al. **Oxidative Metabolism as a Modulator of Kratom's Biological Actions.** Primary mechanistic study describing 3-dehydromitragynine and oxidative metabolites. [PubMed search](https://pubmed.ncbi.nlm.nih.gov/?term=%22Oxidative+Metabolism+as+a+Modulator+of+Kratom%27s+Biological+Actions%22)
25. Philipp AA, Wissenbach DK, Weber AA, Zapp J, Maurer HH. **Metabolism studies of the Kratom alkaloid speciociliatine... in rat and human urine.** *Anal Bioanal Chem.* 2011;399(8):2747-2753. doi:10.1007/s00216-011-4660-9. [PubMed](https://pubmed.ncbi.nlm.nih.gov/21249338/)
26. Philipp AA, Wissenbach DK, Weber AA, Zapp J, Maurer HH. **Metabolism studies of the Kratom alkaloids mitraciliatine and isopaynantheine... in rat and human urine.** *J Chromatogr B.* 2011;879(15-16):1049-1055. doi:10.1016/j.jchromb.2011.03.005. [PubMed](https://pubmed.ncbi.nlm.nih.gov/21450536/)
27. See targeted receptor studies summarized in Hemby et al. 2026 [8] and contemporary functional adrenergic/serotonergic literature; receptor binding without demonstrated signaling is intentionally excluded from the core “activated receptor” map.
28. Gour A, Mukhopadhyay S, Henderson A, et al. **From Kratom to Semi-Synthetic Opioids: The Rise and Risks of MGM-15.** *Drug Test Anal.* 2025;17(12):2384-2389. doi:10.1002/dta.3952. [PubMed](https://pubmed.ncbi.nlm.nih.gov/40936282/)
29. Matsumoto K, Narita M, Muramatsu N, et al. **Orally active opioid μ/δ dual agonist MGM-16, a derivative of the indole alkaloid mitragynine, exhibits potent antiallodynic effect on neuropathic pain in mice.** *J Pharmacol Exp Ther.* 2014;348(3):383-392. doi:10.1124/jpet.113.208108. [PubMed](https://pubmed.ncbi.nlm.nih.gov/24345467/)
30. Contemporary 2026 product-chemistry studies and multicriteria LC-MS work demonstrate semisynthetic signatures, product variability, and the need for reference-standard/chromatographic confirmation; see Sheehan et al. [13] and related 2026 analytical literature.
31. **Development of an ELISA for detection of mitragynine and its metabolites in human urine.** 2020. PMID 32302607. [PubMed](https://pubmed.ncbi.nlm.nih.gov/32302607/)
32. **Analytical method validation with development for the detection and quantification of kratom alkaloids using LC-MS/MS.** 2026. PMID 41500392. [PubMed](https://pubmed.ncbi.nlm.nih.gov/41500392/)

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## Suggested citation language for the EusomniaMD website

> **This reference synthesizes peer-reviewed human pharmacokinetic studies, human urinary-metabolism studies, receptor pharmacology, analytical toxicology, and emerging 2025-2026 literature on concentrated and semisynthetic kratom-derived opioids. Where direct human data are unavailable, the limitation is stated explicitly rather than replaced with animal or in-vitro estimates.**

## Editorial note

This document intentionally separates **native plant alkaloids**, **human metabolites**, **chemical degradation/oxidation products**, and **semisynthetic analogues**. These categories are frequently blurred in commercial descriptions and even in portions of the secondary literature. That distinction should be maintained throughout the public-facing website.