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Memantine

Memantine molecule structureMemantine molecule structure
3,5-Dimethyl-1-aminoadamantane
Namenda, Ebixa, Axura, Memaxa, Namenda XR
Psychoactive Class
DissociativeNootropic
Chemical Class
Adamantane derivative

Memantine is an adamantane derivative and NMDA receptor antagonist primarily prescribed for the management of moderate-to-severe Alzheimer's disease.citation needed It works by blocking glutamate-mediated neuronal excitotoxicity, distinguishing it mechanistically from the cholinesterase inhibitors typically used in Alzheimer's treatment.12 At supratherapeutic doses, memantine can produce prolonged dissociative effects reportedly lasting 16 or more hours, placing it among the longest-duration dissociatives available.

Dosage & Duration

Dosage

Doses are population estimates that vary widely between individuals.

Threshold~10 mg
Light10-30 mg
Moderate30-50 mg
Strong50-80 mg
Heavy80+ mg
Bioavailability
~100%34

Duration

Onset30-90 minutes
After Effects1-72 hours
Total12-72 hours
Half-life
60–80 hours

Subjective Effects

Legacy content. A statistically backed ontology from Mindstate Design Labs is coming soon.

Memantine is an NMDA receptor antagonist whose subjective profile is fundamentally dissociative, though its character is far removed from faster-acting dissociatives. Even therapeutic doses have been found to produce mild dissociative-like effects, while supratherapeutic doses can bring on a prolonged dissociative 'hole' lasting up to 16 or more hours. Notably, it appears to lack the euphoria associated with many recreational substances, and its extremely long duration makes recreational use uncommon.

Physical

The body experience is dominated by CNS depression, including dizziness, drowsiness, sedation, lethargy, and slurred speech, with heavier exposures capable of progressing to loss of consciousness.

Sedation

Cognitive

The headspace is marked by dissociation, confusion, and disorientation, sometimes accompanied by anxiety or agitation. Because NMDA antagonism interferes with the synaptic plasticity underlying learning and memory, higher doses can impair memory formation.

Disorienting

Anxiety

Visual

Hallucinatory States

Reported in a subset of users rather than as a consistent effect.

See also: Dissociative Intensity Scale, Subjective Effects of Dissociatives

Reagent Testing

Expected colorimetric results for common reagent tests. Colors show reaction change over 1–2 minutes.

Mandelin(MD)
yellow2 → orange2 → red2
Simons(SI)
orange1 → red1 → purple2 → purple3
Marquis(MQ)
No reaction
No reaction
Liebermann(LB)
No reaction
No reaction
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Pharmacology

Pharmacodynamics

Memantine acts as an uncompetitive antagonist of the NMDA receptor, binding within the open ion channel to block pathological calcium influx driven by excessive glutamate signaling.citation needed It displays preferential inhibition of extrasynaptic NMDA receptors, while its low affinity and rapid off-rate kinetics allow normal synaptic NMDA function to be preserved during physiological glutamate release.56 Beyond its primary mechanism, memantine acts as a non-competitive antagonist at 5-HT3 receptors with potency similar to its NMDA activitycitation needed and as an antagonist at α7 nicotinic acetylcholine receptors.6 It has additionally been reported to act as an agonist at dopamine D2High receptors7 and as a weak agonist at sigma-1 receptors.

Pharmacokinetics

Memantine has an oral bioavailability of approximately 100%4 and reaches peak plasma levels within 3 to 7 hours.8 It undergoes negligible metabolism by cytochrome P450 enzymes,8 producing three minor metabolites that retain minimal NMDA receptor antagonist activity.citation needed The drug is eliminated primarily through renal excretion, with 57 to 82% appearing unchanged in urine.9 Its elimination half-life ranges from 60 to 80 hours,8 and renal clearance is dependent on urinary pH, with more alkaline urine slowing elimination.8

Interactions

Caution

Use caution

These combinations are not usually physically harmful, but may produce undesirable effects, such as physical discomfort or overstimulation. Extreme use may cause physical health issues. Synergistic effects may be unpredictable. Care should be taken when choosing to use this combination.

AbacavirAbrocitinibAcebutololAceclofenacAcemetacin
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Tolerance

Tolerance timelines are rules of thumb, not exact schedules, and vary widely between individuals and use patterns.

Cross Tolerance

Other NMDA receptor antagonists

Harm Potential

Addiction & Dependence

Psychological

Extremely Low

Recreational use is rare due to the drug's very long duration of action (>40 hours) and apparent lack of euphoric effects. Misuse potential is considered limited compared to other NMDA receptor antagonists.citation needed

Toxicity

Cardiovascular

Blood clots and heart failure have been reported as severe but rare adverse effects, primarily documented in clinical use among elderly patients with dementia.citation needed

Urinary System

Cystitis has been reported as a less common adverse effect in clinical settings.

Psychosis Risk

Psychosis is listed as a severe but rare side effect.citation needed Hallucinations and confusion are more common adverse effects (≥1% of patients) in clinical populations.10 At supratherapeutic recreational doses, dissociative effects may produce psychotomimetic symptoms.

History & Culture

Discovery and Development

Memantine was first synthesized and patented by Eli Lilly and Company in 1963, originally developed as a potential anti-diabetic agent.citation needed However, the compound proved ineffective at lowering blood sugar and the project stalled. Nearly a decade later, in 1972, researchers discovered…

Legality

By Country

Prescription8
United States flagUnited StatesPrescription medication (Rx-only)
Canada flagCanadaPrescription only
Denmark flagDenmarkPrescription only
European Union flagEuropean UnionPrescription only
Germany flagGermanyPrescription only
Netherlands flagNetherlandsPrescription only
Switzerland flagSwitzerlandPrescription only
United Kingdom flagUnited KingdomPrescription only

References

Source Pages

  1. Bluelight: Memantine higher dose discussion
  2. Bluelight: Memantine megathread
  3. DrugBank
  4. Erowid Experience: A Few Words of Caution (exp32398)
  5. Erowid Experience: Being Disconnected From Reality (exp109789)
  6. Erowid Experience: Useful But Not Recreational (exp108837)
  7. Erowid: Memantine Vault
  8. PsychonautWiki: Memantine
  9. Wikipedia

Citations

  1. Memantine — StatPearls. NCBI Bookshelf / StatPearls Publishing (n.d.). https://www.ncbi.nlm.nih.gov/books/NBK500025/1
  2. Memantine and Cholinesterase Inhibitors: Complementary Mechanisms in the Treatment of Alzheimer's Disease. (2013). https://pmc.ncbi.nlm.nih.gov/articles/PMC3753463/1
  3. Shahrina Alam, Kaelyn Skye Lingenfelter, Aaron M. Bender, & Craig W. Lindsley. (September 2017). Classics in Chemical Neuroscience: Memantine. ACS Chemical Neuroscience, 8(9), 1823–1829. https://doi.org/10.1021/acschemneuro.7b0027012
  4. Ebixa 10 mg film-coated tablets Summary of Product Characteristics (SmPC). (emc) (13 December 2021). https://www.medicines.org.uk/emc/product/8222/smpc12
  5. Memantine preferentially blocks extrasynaptic over synaptic NMDA receptor currents in hippocampal autapses. The Journal of Neuroscience, 30(33), 11246–11250 (August 2010). https://doi.org/10.1523/jneurosci.2488-10.20101
  6. Pharmacodynamics of Memantine: An Update. Current Neuropharmacology (n.d.). https://pmc.ncbi.nlm.nih.gov/articles/PMC2645549/12
  7. Memantine agonist action at dopamine D2High receptors. Synapse, 62(2), 149–153 (February 2008). https://doi.org/10.1002/syn.204721
  8. NAMENDA (memantine hydrochloride) Tablets — Prescribing Information. DailyMed (n.d.). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=bc6e059d-1951-4fa3-b904-230d4165724d1234
  9. Namenda (Memantine) for Moderate-to-Severe Alzheimer's Disease — Pharmacotherapy Update. Cleveland Clinic (n.d.). https://www.clevelandclinicmeded.com/medicalpubs/pharmacy/mayjune2004/namenda.htm1
  10. Namenda- memantine hydrochloride tablet; Namenda- memantine hydrochloride kit. DailyMed (1 November 2018). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=b9f27baf-aa2a-443a-9ef5-e002d23407ba1234

Further Reading

  1. Clinical review (PMC2762361)
  2. Drugs.com – Alcohol interaction
  3. Drugs.com – Ketamine + Memantine interaction
  4. Memantine misuse and social networks: Reddit analysis (PMC)
  5. Memantine vs Ketamine NMDAR study
  6. Nervewing: Ether + Memantine
  7. Pharmacokinetics of memantine (PMC6822834)
  8. Reddit: r/ResearchChemicals - 500mg trip report

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