Memantine Stats & Data
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DrugBankDescription
Initially approved by the FDA in 2013, memantine is an N-methyl-D-aspartate (NMDA) receptor antagonist used in the management of Alzheimer's Disease (AD). It is different from many other Alzheimer's Disease medications, as it works by a different mechanism than the cholinesterase enzyme inhibitors normally employed in the management of Alzheimer's disease . Memantine blocks the effects of glutamate, a neurotransmitter in the brain that leads to neuronal excitability and excessive stimulation in Alzheimer's Disease . In 2010, it was estimated that 36 million people worldwide live with Alzheimer's Disease. In 2013, this number increased to 44 million. Almost doubling every 20 years, the prevalence of Alzheimer's Disease is predicted to reach 66 million by 2030 and to 115 million by 2050 . In December 2013, the G8 dementia summit concluded that dementia should be considered a global priority with the objective of developing a cure or a disease-modifying therapy by the year 2025 .
Mechanism of Action
Continuous activation of the N-methyl-D-aspartate (NMDA) receptors in the central nervous system caused by _glutamate_ is thought to cause some of the Alzheimer's disease symptoms. This overactivation is thought to contribute to neurotoxicity due to the excitatory properties of glutamate . The pharmacological effect of memantine likely occurs via the drug's behavior as an uncompetitive (open-channel) NMDA receptor antagonist, preventing glutamate action on this receptor. Memantine has a preference for the NMDA receptor-operated cation channels. Despite these antagonist effects, memantine has not been proven to prevent or retard the neurodegeneration seen in patients diagnosed with Alzheimer’s disease .
Pharmacodynamics
**General effects** This drug inhibits calcium influx into cells that is normally caused by chronic NMDA receptor activation by glutamate . This leads to the improvement of Alzheimer's dementia symptoms, demonstrated by increased cognition and other beneficial central nervous system effects . **Effects on neuroplasticity** Like other NMDA receptor antagonists, memantine at high doses can reduce neuronal synaptic plasticity that is involved in learning and memory processes. At lower concentrations, which are normally used in the clinical setting, memantine can enhance neuronal synaptic plasticity in the brain, improve memory, and act as a neuroprotectant against the destruction of neurons caused by excitatory neurotransmitters . **Effect on various receptors** Memantine has demonstrated minimal activity for GABA, benzodiazepine, dopamine, adrenergic, histamine, and glycine receptors, as well as voltage-dependent Ca2+, Na+ or K+ channels. This drug has shown antagonist activity at the 5HT3 receptors. Laboratory studies suggest that memantine does not affect the reversible inhibition of the acetylcholinesterase normally caused by donepezil, galantamine, or tacrine .
Metabolism
This drug is partially metabolized in the liver. The hepatic CYP450 enzyme system does not majorly contribute to the metabolism of this drug .
Absorption
After an oral dose, memantine is well absorbed. Its peak drug concentrations are attained in about 3-7 hours. Memantine shows linear pharmacokinetics when given at normal therapeutic doses. This drug can be taken without regard to food, as there is no effect of food on memantine absorption .
Toxicity
**LD50** Oral LD50, mouse 437-498 mg/kg Oral LD50, rat 328-370 mg/kg **Carcinogenesis, Mutagenesis, Impairment of Fertility** No evidence of carcinogenicity was seen in mouse and rat models administered memantine at doses equivalent to supratherapeutic human doses . Additionally, no genotoxic potential was noted when a battery of assays was performed. No effects on fertility or reproductive performance were noted in rats given to 18 mg/kg/day (equivalent to 9 times the maximum recommended human dose) orally from 14 days preceding mating through gestation and lactation in females, or for 60 preceding mating activity in males animals . **Use in pregnancy** This drug is considered a pregnancy category B drug, meaning no sufficiently controlled and adequate studies of memantine in pregnant women have been performed. This drug should be taken during pregnancy only if the potential benefit justifies the possible fetal risk . **Use in nursing** It is unknown whether memantine is excreted in human milk. Due to that fact that many drugs are found excreted in human milk, caution should be observed when this drug is taken by a nursing mother .
Indication
Memantine is used to manage moderate to severe Alzheimer's dementia . A more recent systemic review and meta-analysis indicates that memantine is beneficial as a first line drug for the treatment of Alzheimer's dementia. Cholinesterase inhibitors may be added to memantine for further beneficial effects on behavioral symptoms and other symptoms of dementia .
Half-life
Within the range of 60-100 hours . The terminal elimination half-life was significantly increased in patients with moderate to severe renal impairment, in comparison with patients with normal renal function . Exercise caution when this drug is administered to patients with renal dysfunction.
Protein Binding
The protein binding for memantine is about 45% .
Elimination
This drug is mainly excreted in the urine. Approximately 48% of administered memantine is excreted unchanged in urine . The remainder of the drug is metabolized to three main metabolites. These metabolites are the N-glucuronide conjugate, 6-hydroxy memantine, and 1-nitroso-deaminated memantine, which show minimal NMDA receptor antagonist activity .
Volume of Distribution
The mean volume of distribution of memantine is 9-11 L/kg .
Clearance
This drug is cleared by active tubular secretion in the kidneys. Tubular reabsorption of this drug is pH dependent .
Receptor Profile
Receptor Actions
Receptor Binding
History & Culture
1963–1989
Memantine was first synthesized and patented by Eli Lilly and Company in 1963, originally developed as a potential anti-diabetic agent. However, the compound proved ineffective at lowering blood sugar and the project stalled. Nearly a decade later, in 1972, researchers discovered that memantine possessed central nervous system activity, prompting Merz to acquire and develop the compound for neurological conditions, initially focusing on Parkinson's disease. The drug's mechanism of action remained unclear during early development. Researchers initially theorized that memantine worked through direct or indirect modulation of dopaminergic, noradrenergic, and serotonergic systems. It was not until 1989—after clinical trials had already begun—that memantine was identified as an NMDA receptor antagonist. The earlier proposed mechanisms were subsequently recognized to occur only at concentrations approximately 100-fold higher than those achieved at therapeutic doses.
1986–2003
Memantine was first studied for the treatment of Alzheimer's disease in 1986. Three years later, in 1989, the drug received approval and was first marketed for dementia in Germany under the brand name Axura, making it one of the earliest NMDA receptor antagonists used clinically for neurodegenerative disease. International expansion accelerated in 2000, when Merz established partnerships with several pharmaceutical companies: Forest Laboratories for development in the United States under the brand name Namenda, Suntory for the Japanese market, and Lundbeck for Europe and other markets under the name Ebixa. These collaborations facilitated regulatory approval in the European Union in 2002 and in the United States in 2003. By 2023, memantine had become the 145th most commonly prescribed medication in the United States, with over three million prescriptions dispensed annually.
Recreational use of memantine at supratherapeutic doses has been documented. As a weak NMDA receptor antagonist, the drug produces dissociative effects reminiscent of phencyclidine at sufficiently high doses, and even therapeutic doses have been observed to produce mild dissociative-like effects in clinical studies. Research examining self-reported use on Reddit revealed that memantine is used both recreationally for its dissociative properties and as a nootropic for perceived cognitive enhancement. The same analysis identified patterns of self-medication for various conditions without strong scientific basis supporting such uses. The drug's very long duration of action, exceeding 40 hours, has likely limited its appeal for recreational misuse compared to shorter-acting dissociatives. Similar patterns of non-medical use have been observed with the structurally related compound amantadine.
Effect Profile
Curated + 40 ReportsStrong dissociative depth, motor impairment, and mania with moderate insight
Strong stimulation and euphoria with moderate anxiety/jitters and focus
Tolerance & Pharmacokinetics
drugs.wikiTolerance Decay
Anecdotal reports suggest tolerance builds with frequent or daily use and decays over weeks of abstinence; cross-tolerance among NMDA antagonists is commonly reported by users but lacks controlled human data. Given memantine’s long half-life, apparent tolerance may reflect persistent baseline plasma levels rather than receptor-level adaptations. Data quality: anecdotal.
Cross-Tolerances
Demographics
Gender Distribution
Age Distribution
Reports Over Time
Effect Analysis
Erowid + BluelightEffects aggregated from 40 experience reports (30 Erowid + 10 Bluelight)
Effect Sentiment Distribution
Confidence Distribution
Positive Effects 33
Adverse Effects 21
Dosage Distribution
Dose distribution from experience reports
Real-World Dose Distribution
62K DosesFrom 52 individual dose entries
Oral (n=46)
Common Combinations
Most co-occurring substances in experience reports
Form / Preparation
Most common forms and preparations reported
Body-Weight Dosing
Dose relative to body weight from reports with weight data
Redose Patterns
Redosing behavior across 22 reports
Legal Status
| Country | Status | Notes |
|---|---|---|
| Canada | Prescription medication | Approved pharmaceutical available by prescription. Generic and brand name formulations have been marketed since at least 2010, including products from multiple labellers. |
| European Union | Prescription medication | Approved and marketed as a prescription pharmaceutical across EU member states. Brand name products including Axura have been available since at least 2016. |
| United States | Prescription medication (Rx-only) | FDA-approved in 2013 for the management of Alzheimer's disease. Not a scheduled controlled substance under the Controlled Substances Act. Available only by prescription; generic and brand name formulations are marketed. |
Harm Reduction
drugs.wiki— Long half-life and accumulation: Memantine’s elimination half-life is ~60–80 h, with renal clearance influenced by urine pH via pH-dependent tubular reabsorption; accumulation and prolonged effects are common, so spacing trials by ≥48–72 h reduces unintended multi-day intoxication. Source: StatPearls (pharmacokinetics). — Urine alkalinization: Raising urinary pH (≈8) can reduce clearance ~80%, substantially increasing exposure and adverse-effect risk; this occurs with carbonic anhydrase inhibitors (acetazolamide, topiramate, zonisamide) and alkalinizing agents (e.g., sodium bicarbonate, potassium citrate). List alkalinizers as dangerous/unsafe interactions. Source: StatPearls (drug–drug interactions); StatPearls (cystinuria management showing potassium citrate alkalinizes urine). — Renal impairment: In moderate–severe renal impairment, AUC roughly increases 60–115% and half-life increases 41–95%; recreational high dosing should be avoided or minimized to prevent prolonged toxicity. Source: StatPearls (renal impairment PK). — CNS depressants: Memantine can cause dizziness/somnolence; combining with alcohol, opioids, benzodiazepines or barbiturates increases risks of accidents, aspiration, and amnesia. This is a general CNS safety principle supported by the memantine adverse-effect profile. Source: StatPearls (adverse effects). — Other NMDA antagonists: Combining with amantadine, ketamine, or dextromethorphan increases neuropsychiatric adverse events; therefore, list as dangerous/unsafe combinations. Source: StatPearls. — Cardiovascular and stimulant caution: Memantine has been associated with hypertension and tachycardia; stimulants and nicotine can additively increase heart rate/blood pressure; advise caution, especially in CVD. Source: StatPearls (adverse effects). — Psychiatric risk: Uncommon adverse effects include hallucinations, agitation, and rare serious neuropsychiatric syndromes; mania-like reactions are reported anecdotally with high/repeated doses. Warn users with mood/psychotic disorders. Source: StatPearls (adverse effects); user reports. — Driving/next-day impairment: Due to long half-life and delayed offset, cognition/coordination can remain impaired ≥24–72 h; advise against driving/operating machinery the day of use and potentially the following day. Supported by PK and many user reports describing prolonged after-effects. Sources: StatPearls; user reports. — Route of administration: Non-oral routes are discouraged; IM reports note burning/irritation and unpredictable kinetics. Emphasize oral-only. Source: Bluelight first-time caution thread. — Titration/redosing: Because onset may be delayed (1–3 h) and effects last long, early redosing can result in stacking and protracted dissociation; advise small single trials and avoid boosters within the same day. Sources: StatPearls (onset for ER; long t1/2) and user reports/experience vaults. — Hepatic safety: Clinically apparent hepatotoxicity is rare, but has been reported; advise avoiding heavy alcohol binges and monitoring for jaundice if used repeatedly. Source: LiverTox. — Pregnancy/lactation/pediatrics: Safety not established; avoid non-medical use in pregnancy or while breastfeeding and avoid pediatric exposure. Source: StatPearls. — Product form: Distinguish IR vs ER; do not crush ER beads; verify tablet identity (avoid counterfeits). Source: StatPearls (dosage forms/ER specifics). — Set/setting and sitter: Dissociation plus amnesia raises accident risk; a sober sitter and safe environment reduce harms; Erowid experiential literature repeatedly highlights prolonged and unpredictable effects. Sources: Erowid experience vaults.
References
Cited References
- Bluelight: Memantine megathread
- Bluelight: Memantine higher dose discussion
- Erowid: Memantine Vault
- Erowid Experience: A Few Words of Caution (exp32398)
- Erowid Experience: Useful But Not Recreational (exp108837)
- Erowid Experience: Being Disconnected From Reality (exp109789)
- Memantine misuse and social networks: Reddit analysis (PMC)
- NCBI: StatPearls - Memantine
- Pharmacokinetics of memantine (PMC6822834)
- PsychonautWiki: Memantine
- Rammes et al. - Pharmacodynamics of Memantine (PMC2645549)
- Reddit: r/ResearchChemicals - 500mg trip report
- Nervewing: Ether + Memantine
- Clinical review (PMC2762361)
- Memantine vs Ketamine NMDAR study
- Drugs.com – Ketamine + Memantine interaction
- Drugs.com – Alcohol interaction
Drugs.wiki References
- StatPearls – Memantine (mechanism, PK, dosing, DDIs, adverse effects)
- DrugBank – Memantine (synonyms, metabolites, half-life)
- LiverTox – Memantine (rare hepatotoxicity)
- Erowid Experience Vaults – Memantine (user reports)
- Bluelight – Memantine first-time caution (non-oral route irritancy; prolonged effects)