Methylecgonidine

Methylecgonidine at a Glance

Methylecgonidine — more formally anhydroecgonine methyl ester (AEME) — is a small tropane alkaloid built on the same ecgonine skeleton as cocaine, but lacking cocaine’s benzoyl group. It is best understood through its double identity: it is a genuine natural alkaloid of the coca seed, and, quite separately, it is the signature product formed when cocaine base is pyrolysed (smoked) ^{1,7Reference 1Casale JF et al. · 2005Alkaloid content of the seeds from Erythroxylum coca var. cocaView study →Reference 7Toennes SW et al. · 1999Gas chromatographic-mass spectrometric detection of anhydroecgonine methyl ester (methylecgonidine) in human serum as evidence of recent smoking of crackView study →}.

That second identity is why the molecule matters clinically and forensically. Because AEME is generated by heat and is largely absent from cocaine taken by other routes, its presence in blood, urine or hair is used as a biomarker of smoked-cocaine exposure ^{7,8Reference 7Toennes SW et al. · 1999Gas chromatographic-mass spectrometric detection of anhydroecgonine methyl ester (methylecgonidine) in human serum as evidence of recent smoking of crackView study →Reference 8Kintz P et al. · 1995Testing human hair and urine for anhydroecgonine methyl ester, a pyrolysis product of cocaineView study →}. It is not a pharmacologically inert marker, though: unlike cocaine — a monoamine-reuptake blocker — AEME behaves as a muscarinic (cholinergic) agonist, and animal and cell studies implicate it in the cardiorespiratory and neurological harms of smoked cocaine ^{2,3Reference 2Scheidweiler KB et al. · 2003Pharmacokinetics and pharmacodynamics of methylecgonidine, a crack cocaine pyrolyzateView study →Reference 3Garcia RCT et al. · 2012RCTNeurotoxicity of anhydroecgonine methyl ester, a crack cocaine pyrolysis productView study →}.

This page treats AEME as a phytochemistry and toxicology entry. It covers what the molecule is, where it genuinely occurs in the plant, and what the toxicology literature reports — with no description of how cocaine is prepared or smoked.

The Seed Alkaloid That Is Also The Smoked-Cocaine Marker

Two threads define this molecule, and keeping them separate is the whole point of the page.

Thread one — a true coca-seed alkaloid. When the alkaloids of Erythroxylum coca var. coca seeds were profiled, methylecgonidine was found to be the primary constituent of the seed, and specifically not an analytical artefact of the extraction ^{1Reference 1Casale JF et al. · 2005Alkaloid content of the seeds from Erythroxylum coca var. cocaView study →}. This is an important and easily-missed distinction: AEME is often assumed to exist only as a decomposition product, but in coca seed it is a native alkaloid. Note that this is the seed, not the chewed leaf — the seed alkaloid profile differs from the consumed leaf, where cocaine dominates and AEME is at most a trace component.

Thread two — the smoked-cocaine pyrolysis marker. Separately and far more consequentially for public health, AEME forms when cocaine base is heated and inhaled: thermal elimination of benzoic acid from cocaine yields anhydroecgonine methyl ester in the smoke ^{7Reference 7Toennes SW et al. · 1999Gas chromatographic-mass spectrometric detection of anhydroecgonine methyl ester (methylecgonidine) in human serum as evidence of recent smoking of crackView study →}. Because it is produced by heat and appears in body fluids after smoking but little or not at all after intravenous or intranasal cocaine, AEME (and its downstream hydrolysis product anhydroecgonine) serve as forensic biomarkers that distinguish smoking from other routes of cocaine use ^{7,8Reference 7Toennes SW et al. · 1999Gas chromatographic-mass spectrometric detection of anhydroecgonine methyl ester (methylecgonidine) in human serum as evidence of recent smoking of crackView study →Reference 8Kintz P et al. · 1995Testing human hair and urine for anhydroecgonine methyl ester, a pyrolysis product of cocaineView study →}. It has been detected in human serum, urine and hair, including in the hair of exposed neonates ^{7,8Reference 7Toennes SW et al. · 1999Gas chromatographic-mass spectrometric detection of anhydroecgonine methyl ester (methylecgonidine) in human serum as evidence of recent smoking of crackView study →Reference 8Kintz P et al. · 1995Testing human hair and urine for anhydroecgonine methyl ester, a pyrolysis product of cocaineView study →}.

The reason toxicologists care about the marker being present — rather than treating it as a passive tracer — is that AEME is pharmacologically active in its own right, and by a different mechanism than cocaine. Where cocaine acts on monoamine transporters and sodium channels, AEME acts on muscarinic acetylcholine receptors, and is a suspected contributor to the cardiorespiratory and neurological toxicity that is worse with smoked cocaine than with other routes ^{2,3,6Reference 2Scheidweiler KB et al. · 2003Pharmacokinetics and pharmacodynamics of methylecgonidine, a crack cocaine pyrolyzateView study →Reference 3Garcia RCT et al. · 2012RCTNeurotoxicity of anhydroecgonine methyl ester, a crack cocaine pyrolysis productView study →Reference 6Romero-Noreña A et al. · 2024Systematic reviewToxicology of anhydroecgonine methyl ester: a systematic review of a cocaine pyrolysis productView study →}.

What It's Used For

The evidence base is small, almost entirely animal and in-vitro, and centres on two questions: is AEME a reliable marker of smoked cocaine (a forensic-analytical question, well answered in humans), and does it contribute independently to toxicity (a mechanistic question, answered so far only in cells and animals).

Evidence by IndicationStrength of support · Beta

Support is an experimental score — weighted by study type (human > animal > in vitro) and volume. A beta, not a validated metric. The forensic-marker row rests on human data; the toxicity rows are preclinical, so read the per-row basis.

01Forensic Biomarker Of Smoked CocainePromising54%Human serum/urine/hair detection; route-specific to smoking ^{7,8Reference 7Toennes SW et al. · 1999Gas chromatographic-mass spectrometric detection of anhydroecgonine methyl ester (methylecgonidine) in human serum as evidence of recent smoking of crackView study →Reference 8Kintz P et al. · 1995Testing human hair and urine for anhydroecgonine methyl ester, a pyrolysis product of cocaineView study →}

02Neurotoxicity (Muscarinic / Apoptotic)Shaky38%Rat neuronal cells; greater potency than cocaine, additive with it ^{3,5Reference 3Garcia RCT et al. · 2012RCTNeurotoxicity of anhydroecgonine methyl ester, a crack cocaine pyrolysis productView study →Reference 5Garcia RCT et al. · 2017RCTAnhydroecgonine methyl ester, a cocaine pyrolysis product, may contribute to cocaine behavioral sensitizationView study →}

03Cardiorespiratory Toxicity (Muscarinic Agonism)Shaky32%Sheep in vivo + in-vitro cardiac/airway data; atropine-reversible ^{2,4Reference 2Scheidweiler KB et al. · 2003Pharmacokinetics and pharmacodynamics of methylecgonidine, a crack cocaine pyrolyzateView study →Reference 4Garcia RCT et al. · 2015RCTM1 and M3 muscarinic receptors may play a role in the neurotoxicity of anhydroecgonine methyl ester, a cocaine pyrolysis productView study →}

Mechanisms

The load-bearing point: AEME’s toxicity runs through the cholinergic/muscarinic system, which is mechanistically distinct from cocaine’s monoamine-reuptake and sodium-channel actions — so it adds a different flavour of harm rather than simply more cocaine.

Pharmacokinetics

Methylecgonidine is cleared quickly: in sheep its blood half-life was ~18–21 minutes, while its hydrolysis product anhydroecgonine persisted much longer (~94–137 minutes) ^{2Reference 2Scheidweiler KB et al. · 2003Pharmacokinetics and pharmacodynamics of methylecgonidine, a crack cocaine pyrolyzateView study →}. In humans, AEME is hydrolysed by butyrylcholinesterase and by non-enzymatic processes to anhydroecgonine, so the pair is used together as smoking markers, with the longer-lived metabolite widening the detection window ^{6,8Reference 6Romero-Noreña A et al. · 2024Systematic reviewToxicology of anhydroecgonine methyl ester: a systematic review of a cocaine pyrolysis productView study →Reference 8Kintz P et al. · 1995Testing human hair and urine for anhydroecgonine methyl ester, a pyrolysis product of cocaineView study →}. The fast clearance of the parent molecule is one reason serum AEME indicates recent smoking specifically ^{7Reference 7Toennes SW et al. · 1999Gas chromatographic-mass spectrometric detection of anhydroecgonine methyl ester (methylecgonidine) in human serum as evidence of recent smoking of crackView study →}. No oral bioavailability figure is relevant — the real-world exposure route is inhalational, involuntary and non-therapeutic.

Clinical Trials

There are no therapeutic clinical trials of methylecgonidine — it is a toxicant and a forensic marker, not a candidate drug. The human literature is analytical-toxicology (biomarker detection in serum, urine and hair) ^{7,8Reference 7Toennes SW et al. · 1999Gas chromatographic-mass spectrometric detection of anhydroecgonine methyl ester (methylecgonidine) in human serum as evidence of recent smoking of crackView study →Reference 8Kintz P et al. · 1995Testing human hair and urine for anhydroecgonine methyl ester, a pyrolysis product of cocaineView study →}; the mechanistic toxicity work is preclinical ^{2,3,4,5Reference 2Scheidweiler KB et al. · 2003Pharmacokinetics and pharmacodynamics of methylecgonidine, a crack cocaine pyrolyzateView study →Reference 3Garcia RCT et al. · 2012RCTNeurotoxicity of anhydroecgonine methyl ester, a crack cocaine pyrolysis productView study →Reference 4Garcia RCT et al. · 2015RCTM1 and M3 muscarinic receptors may play a role in the neurotoxicity of anhydroecgonine methyl ester, a cocaine pyrolysis productView study →Reference 5Garcia RCT et al. · 2017RCTAnhydroecgonine methyl ester, a cocaine pyrolysis product, may contribute to cocaine behavioral sensitizationView study →}.

Last checked: July 2026.

Isolate vs. Plant Studies

Almost the entire literature concerns the isolated molecule, not a plant extract — appropriately, because the health-relevant exposure is not botanical. The neurotoxicity, muscarinic-agonism and cardiovascular studies all dose pure AEME (or AEME with pure cocaine) in cells and animals ^{2,3,4Reference 2Scheidweiler KB et al. · 2003Pharmacokinetics and pharmacodynamics of methylecgonidine, a crack cocaine pyrolyzateView study →Reference 3Garcia RCT et al. · 2012RCTNeurotoxicity of anhydroecgonine methyl ester, a crack cocaine pyrolysis productView study →Reference 4Garcia RCT et al. · 2015RCTM1 and M3 muscarinic receptors may play a role in the neurotoxicity of anhydroecgonine methyl ester, a cocaine pyrolysis productView study →}, and the forensic studies detect the pure analyte in human specimens ^{7,8Reference 7Toennes SW et al. · 1999Gas chromatographic-mass spectrometric detection of anhydroecgonine methyl ester (methylecgonidine) in human serum as evidence of recent smoking of crackView study →Reference 8Kintz P et al. · 1995Testing human hair and urine for anhydroecgonine methyl ester, a pyrolysis product of cocaineView study →}. The one genuinely botanical fact — that AEME is the primary alkaloid of the coca seed and not an artefact ^{1Reference 1Casale JF et al. · 2005Alkaloid content of the seeds from Erythroxylum coca var. cocaView study →} — is a plant-chemistry finding, not a plant-exposure one: the seed is not the consumed part of coca, and the chewed leaf that people actually use is dominated by cocaine, with AEME a trace component at most. So there is essentially no “whole-plant AEME exposure” story to caveat; the molecule’s importance is as a pure pyrolysis product.

Prevalence in Nature

In the plant kingdom methylecgonidine is effectively confined to the genus Erythroxylum. Its documented natural occurrence is as the primary alkaloid of Erythroxylum coca var. coca seeds, where careful analysis established it as a true constituent rather than a breakdown product formed during extraction ^{1Reference 1Casale JF et al. · 2005Alkaloid content of the seeds from Erythroxylum coca var. cocaView study →}. It sits within the coca tropane-alkaloid family alongside cocaine, cinnamoylcocaine, benzoylecgonine, ecgonine methyl ester and ecgonine — but unlike cocaine, which concentrates in the leaf (~0.5–1% dry weight of the consumed part), AEME’s native abundance is a seed phenomenon and is not quantified here as a leaf content. Its far larger real-world presence is non-botanical: as a component of smoked-cocaine smoke ^{7Reference 7Toennes SW et al. · 1999Gas chromatographic-mass spectrometric detection of anhydroecgonine methyl ester (methylecgonidine) in human serum as evidence of recent smoking of crackView study →}. See the coca monograph — /herb/coca — for the leaf’s alkaloid profile.

Discovery & Synthesis

Methylecgonidine entered the scientific record chiefly through forensic toxicology, where it was characterised from the 1990s onward as the marker that betrays smoked cocaine: work by Kintz and colleagues detected it in human hair and urine ^{8Reference 8Kintz P et al. · 1995Testing human hair and urine for anhydroecgonine methyl ester, a pyrolysis product of cocaineView study →}, and Toennes and colleagues demonstrated it in human serum as evidence of recent crack smoking ^{7Reference 7Toennes SW et al. · 1999Gas chromatographic-mass spectrometric detection of anhydroecgonine methyl ester (methylecgonidine) in human serum as evidence of recent smoking of crackView study →}. Its status as a genuine native alkaloid — as opposed to purely a degradation product — was established for coca seed by Casale, Toske and Colley in 2005 ^{1Reference 1Casale JF et al. · 2005Alkaloid content of the seeds from Erythroxylum coca var. cocaView study →}. Chemically the molecule is anhydroecgonine methyl ester: it corresponds to cocaine that has lost its benzoic-acid group, and it is this thermal elimination of benzoic acid from cocaine that generates AEME in smoke ^{7Reference 7Toennes SW et al. · 1999Gas chromatographic-mass spectrometric detection of anhydroecgonine methyl ester (methylecgonidine) in human serum as evidence of recent smoking of crackView study →}. Consistent with the sensitivity of this molecule, no preparation, extraction or synthesis procedure. Manufacture of AEME today is essentially limited to certified analytical reference standards for toxicology laboratories.

Patents: not yet researched.

Toxicity & Safety

Methylecgonidine carries a toxic flag. The rationale is not its trace natural occurrence in coca seed but its toxicological profile as a smoked-cocaine pyrolysis product: in preclinical models it is more neurotoxic than cocaine, acts as a muscarinic agonist with adverse cardiac and bronchoconstrictor effects, and drives oxidative stress and apoptosis ^{2,3,6Reference 2Scheidweiler KB et al. · 2003Pharmacokinetics and pharmacodynamics of methylecgonidine, a crack cocaine pyrolyzateView study →Reference 3Garcia RCT et al. · 2012RCTNeurotoxicity of anhydroecgonine methyl ester, a crack cocaine pyrolysis productView study →Reference 6Romero-Noreña A et al. · 2024Systematic reviewToxicology of anhydroecgonine methyl ester: a systematic review of a cocaine pyrolysis productView study →}. It is a suspected contributor to why smoking cocaine is harder on the heart and lungs than other routes — though the human contribution is inferred, not directly measured. It is a controlled-substance-adjacent tropane and has no legitimate ingestion route.

Safety at a Glance

☠️ ToxicNeurotoxicity

• A suspected independent toxicant in smoked cocaine. In cells AEME is more neurotoxic than cocaine and additive with it; it drives muscarinic signalling, oxidative stress and apoptosis ^{3,6Reference 3Garcia RCT et al. · 2012RCTNeurotoxicity of anhydroecgonine methyl ester, a crack cocaine pyrolysis productView study →Reference 6Romero-Noreña A et al. · 2024Systematic reviewToxicology of anhydroecgonine methyl ester: a systematic review of a cocaine pyrolysis productView study →}.
• Muscarinic cardiorespiratory effects. In vivo it causes atropine-reversible hypotension and tachycardia, with in-vitro bronchoconstriction and reduced cardiac contractility — a cholinergic profile unlike cocaine’s ^{2,4Reference 2Scheidweiler KB et al. · 2003Pharmacokinetics and pharmacodynamics of methylecgonidine, a crack cocaine pyrolyzateView study →Reference 4Garcia RCT et al. · 2015RCTM1 and M3 muscarinic receptors may play a role in the neurotoxicity of anhydroecgonine methyl ester, a cocaine pyrolysis productView study →}.
• A marker of exposure, not a benign one. Its detection confirms smoked-cocaine exposure; the same routes that create the marker create the toxicity ^{7,8Reference 7Toennes SW et al. · 1999Gas chromatographic-mass spectrometric detection of anhydroecgonine methyl ester (methylecgonidine) in human serum as evidence of recent smoking of crackView study →Reference 8Kintz P et al. · 1995Testing human hair and urine for anhydroecgonine methyl ester, a pyrolysis product of cocaineView study →}.
• Negligible dietary/botanical exposure. Native AEME is confined to coca seed, not the consumed leaf, so ordinary botanical exposure is trivial — the toxicity story is about the pyrolysis product, not the plant.

Dosage

There is no dose for methylecgonidine. It is not an ingested herb, supplement or medicine; it has no established human therapeutic use; and its real-world exposure is involuntary, as a component of smoked-cocaine smoke. The concentration figures cited here (serum, urine and hair levels) are forensic biomarker measurements, not doses, and are reported only to characterise the molecule. Nothing here is a personal recommendation.

References

1. Casale JF, Toske SG, Colley VL (2005). Alkaloid content of the seeds from Erythroxylum coca var. coca. Journal of Forensic Sciences. https://pubmed.ncbi.nlm.nih.gov/16382835/
2. Scheidweiler KB, Plessinger MA, Shojaie J, Wood RW, Kwong TC (2003). Pharmacokinetics and pharmacodynamics of methylecgonidine, a crack cocaine pyrolyzate. Journal of Pharmacology and Experimental Therapeutics. https://pubmed.ncbi.nlm.nih.gov/14561847/
3. Garcia RCT, et al. (2012). Neurotoxicity of anhydroecgonine methyl ester, a crack cocaine pyrolysis product. Toxicological Sciences. https://pubmed.ncbi.nlm.nih.gov/22523227/
4. Garcia RCT, et al. (2015). M1 and M3 muscarinic receptors may play a role in the neurotoxicity of anhydroecgonine methyl ester, a cocaine pyrolysis product. Scientific Reports. https://pubmed.ncbi.nlm.nih.gov/26626425/
5. Garcia RCT, et al. (2017). Anhydroecgonine methyl ester, a cocaine pyrolysis product, may contribute to cocaine behavioral sensitization. Toxicology. https://pubmed.ncbi.nlm.nih.gov/27129946/
6. Romero-Noreña A, Contreras-Martinez HJ, Mendivil-Perez M (2024). Toxicology of anhydroecgonine methyl ester: a systematic review of a cocaine pyrolysis product. Toxicology Reports. https://pubmed.ncbi.nlm.nih.gov/39104366/
7. Toennes SW, Fandiño AS, Kauert G (1999). Gas chromatographic-mass spectrometric detection of anhydroecgonine methyl ester (methylecgonidine) in human serum as evidence of recent smoking of crack. Journal of Chromatography B: Biomedical Sciences and Applications. https://pubmed.ncbi.nlm.nih.gov/10630898/
8. Kintz P, Cirimele V, Sengler C, Mangin P (1995). Testing human hair and urine for anhydroecgonine methyl ester, a pyrolysis product of cocaine. Journal of Analytical Toxicology. https://pubmed.ncbi.nlm.nih.gov/8926742/

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