1. Clinical & Scientific Overview
Memantine Hydrochloride (TIP-MED-000216, Reference Code [11.12]) is classified under
Neurology & Antiepileptic Medicines (Ch 11) as a Low-to-Moderate Affinity, Voltage-Dependent, Uncompetitive NMDA (N-Methyl-D-Aspartate) Glutamate Receptor Antagonist (Neuroprotective Anti-Excitotoxic Agent).
Within the Indian regulatory and compendial framework, it is governed under Schedule H Prescription Drug (To be sold by retail on the prescription of a Registered Medical Practitioner only — Drugs Rules 1945).
Representative Indian Market Examples (Edition 2.7 Ch 11 [11.12], p. 145): Admenta (Sun Pharma), Ebixa (Lundbeck), Nemdaa (Intas), Mentadem; In FDC with Donepezil: Aricep-M, Donep-M, Admenta-Plus — Strengths & Dosage Forms: Oral Film-Coated Scored Tablets: 5 mg, 10 mg; Extended-Release: 14 mg, 28 mg; Common FDCs: Memantine 5 mg or 10 mg + Donepezil 5 mg
Oral Film-Coated Scored Tablets: 5 mg, 10 mg; Extended-Release: 14 mg, 28 mg; Common FDCs: Memantine 5 mg or 10 mg + Donepezil 5 mg
3. Mechanism of Action & Pharmacodynamics
Low-to-Moderate Affinity, Voltage-Dependent, Uncompetitive NMDA (N-Methyl-D-Aspartate) Glutamate Receptor Antagonist (Neuroprotective Anti-Excitotoxic Agent) acting on target receptor/enzyme pathways in Neurology & Antiepileptic Medicines (Ch 11): clinical efficacy is mediated via Low-to-Moderate Affinity, Voltage-Dependent, Uncompetitive NMDA (N-Methyl-D-Aspartate) Glutamate Receptor Antagonist (Neuroprotective Anti-Excitotoxic Agent) for Moderate-to-Severe Alzheimer's Disease (monotherapy when AChEIs are contraindicated due to bradycardia/heart block, or in synergistic combination with Donepezil—Aricep-M / Donep-M—which reduces agitation, aggression, and functional decline)..
4. Therapeutic Indications & Evidence-Supported Uses
- Moderate-to-Severe Alzheimer's Disease (monotherapy when AChEIs are contraindicated due to bradycardia/heart block, or in synergistic combination with Donepezil—Aricep-M / Donep-M—which reduces agitation, aggression, and functional decline)
🇮🇳 Jurisdiction & Indication Note: Indications and schedules reflect Indian compendial and regulatory records (CDSCO / Indian Pharmacopoeia & NFI / NLEM 2022). Where international reference labels (US FDA DailyMed / NCBI StatPearls) are cited for pharmacokinetic or mechanistic parameters, international approvals do not automatically imply CDSCO approval in India.
5. Educational Dosage Context, Formulations & Administration
Educational Dosing & Regimen Summary: General Adult Reference: Stepwise Weekly Titration (to prevent dizziness/confusion): • Week 1: 5 mg once daily in the morning. • Week 2: 5 mg twice daily (10 mg/day). • Week 3: 10 mg morning + 5 mg evening (15 mg/day). • Week 4+: 10 mg twice daily (Maximum 20 mg/day). In Severe Renal Impairment (CrCl 5–29 mL/min): Maximum dose is strictly 5 mg twice daily (10 mg/day)! Follow neurologist prescription.
Administration & Meal Timing: With or without food. | Once daily in the morning (for 5 mg), or twice daily (morning and evening) for 10–20 mg/day.
6. Pharmacokinetics, Metabolism & Renal/Hepatic Adjustment
Absorption, distribution, metabolism, and excretion follow class pharmacokinetic profile; verify patient renal/hepatic function.
Renal: STRICTLY RENAL-FUNCTION DEPENDENT (Excreted 75–90% unchanged in urine via OCT2 tubular secretion; zero hepatic CYP metabolism)! • CrCl ≥30 mL/min: Up to 10 mg twice daily (20 mg/day). • CrCl 5–29 mL/min (Stage 4 CKD): Maximum dose is 5 mg twice daily (or 10 mg once daily)! • CrCl <5 mL/min: Avoid. Hepatic: Minimal hepatic metabolism; no adjustment in mild-to-moderate liver disease.
Renal: STRICTLY RENAL-FUNCTION DEPENDENT (Excreted 75–90% unchanged in urine via OCT2 tubular secretion; zero hepatic CYP metabolism)! • CrCl ≥30 mL/min: Up to 10 mg twice daily (20 mg/day). • CrCl 5–29 mL/min (Stage 4 CKD): Maximum dose is 5 mg twice daily (or 10 mg once daily)! • CrCl <5 mL/min: Avoid. Hepatic: Minimal hepatic metabolism; no adjustment in mild-to-moderate liver disease.
Renal: STRICTLY RENAL-FUNCTION DEPENDENT (Excreted 75–90% unchanged in urine via OCT2 tubular secretion; zero hepatic CYP metabolism)! • CrCl ≥30 mL/min: Up to 10 mg twice daily (20 mg/day). • CrCl 5–29 mL/min (Stage 4 CKD): Maximum dose is 5 mg twice daily (or 10 mg once daily)! • CrCl <5 mL/min: Avoid. Hepatic: Minimal hepatic metabolism; no adjustment in mild-to-moderate liver disease.
7. Contraindications, Precautions & High-Risk Warnings
- Use with caution in epilepsy/seizure history, severe renal impairment, and conditions that alkalinise the urine (pH >7.5–8.0)!
Key Clinical Precautions: Renal: STRICTLY RENAL-FUNCTION DEPENDENT (Excreted 75–90% unchanged in urine via OCT2 tubular secretion; zero hepatic CYP metabolism)! • CrCl ≥30 mL/min: Up to 10 mg twice daily (20 mg/day). • CrCl 5–29 mL/min (Stage 4 CKD): Maximum dose is 5 mg twice daily (or 10 mg once daily)! • CrCl <5 mL/min: Avoid. Hepatic: Minimal hepatic metabolism; no adjustment in mild-to-moderate liver disease.
8. Adverse Effects Profile
- Significantly better tolerated than Donepezil (does NOT cause nausea, vomiting, diarrhoea, or bradycardia!): mild dizziness, headache, constipation (unlike donepezil which causes diarrhoea), somnolence, mild hypertension.
- Hallucinations, confusion, or agitation (if titrated too rapidly or in unadjusted renal failure), rare venous thromboembolism, pancreatitis, seizures.
- Monitor for severe hypersensitivity, organ toxicity, or dose-limiting adverse events.
9. Major Drug–Drug, Drug–Food & Drug–Herb Interactions
- URINARY ALKALINISERS (Disodium Hydrogen Citrate syrups [Citralka/Cital], Sodium Bicarbonate, Carbonic Anhydrase Inhibitors [Acetazolamide]): CRITICAL RENAL CLEARANCE INTERACTION! Memantine is cleared by pH-dependent renal tubular secretion; raising urinary pH from acidic (pH 5
- 0) to alkaline (pH 8
- 0) reduces renal Memantine clearance by 80%, causing massive systemic accumulation and neurotoxicity! 2
- Other NMDA Antagonists (Amantadine, Ketamine, Dextromethorphan [in OTC cough syrups!]): Avoid co-administration—causes additive NMDA CNS psychosis, hallucinations, and dizziness!
10. Clinical Monitoring, Patient Counselling & Storage
Clinical & Laboratory Monitoring: Monitor clinical response, baseline renal/hepatic parameters, and relevant serum biomarkers.
Pharmacist Patient Counselling Points:
- Patient Counselling Checklist: 1. Explain to caregivers that Memantine complements Donepezil by blocking excess toxic glutamate in the brain, often helping calm sundowning agitation and irritability while balancing out Donepezil's loose stools. 2. Warn caregivers against giving OTC Dextromethorphan cough syrups (e.g., Benadryl DR, Corex-DX, Alex) or Urinary Citrate syrups (Citralka) to a dementia patient taking Memantine, as both interact strongly with Memantine!
- Meal & Clock Timing Instruction: With or without food. (Once daily in the morning (for 5 mg), or twice daily (morning and evening) for 10–20 mg/day.)
- Missed Dose Protocol: Skip the missed dose and administer the next scheduled dose (t1/2 is 60–100 hours!). If interrupted for several days, re-titrate from 5 mg OD.
- Geriatric Dispensing Pearl: In elderly dementia patients who cannot tolerate Donepezil due to severe sinus bradycardia (<50 bpm), heart block, or intractable diarrhoea, Memantine (Admenta 5 mg BD) is the ideal non-cholinergic alternative; always cap total dose at 10 mg/day if CrCl <30 mL/min.
Storage, Stability & Dispensing Safeguards: Store below 25°C–30°C in original moisture- and light-resistant packaging out of reach of children. Available forms: Oral Film-Coated Scored Tablets: 5 mg, 10 mg; Extended-Release: 14 mg, 28 mg; Common FDCs: Memantine 5 mg or 10 mg + Donepezil 5 mg
11. Visual Pharmacology & Mechanism Diagram (svg-v339-01-adme-12-step-journey)
12. Authoritative References, Regulatory Sources & Editorial Disclaimer
Primary Compendial & Guideline Reference: Indian Pharmacist Desk Reference — Professional Edition 2.7 (2026–27) • Ch 11 [11.12] (p. 145)
Official Verification Portals: Indian Pharmacopoeia Commission (IPC) & National Formulary of India (NFI) • Central Drugs Standard Control Organization (CDSCO) • Ministry of Health & Family Welfare — NLEM 2022 • NCBI Bookshelf / StatPearls Pharmacology Reference • DailyMed (US FDA Official Prescribing Reference)
Last Medically & Pharmaceutically Reviewed: 2026-11-10 • Verification Status: HANDBOOK_SOURCE_CONTENT
Educational & Clinical Disclaimer: This reference profile is published solely for pharmacy education, academic study, and professional clinical reference. It does not substitute for patient-specific clinical judgement, qualified specialist oncology/medical supervision, or official CDSCO/IP prescribing information. Never self-medicate with prescription, Schedule H/H1/X, NDPS, or oncology medicines.
13. Related Reference Monographs, Educational Guides & Visual Concept
💊 Related Pharmacological / Category Profiles
- [11.15] Diazepam (Oral, IV & Paediatric Rectal Protocol) — Long-Acting Lipophilic Benzodiazepine (Anticonvulsant, Anxiolytic
- [11.16] Midazolam (Parenteral & Intranasal Rescue Protocol) — Short-Acting Water-Soluble Imidazobenzodiazepine (Intranasal / Bu
- [11.27] Levodopa + Carbidopa (Co-Careldopa) & Pramipexole — Dopamine Precursor + Peripheral DOPA Decarboxylase Inhibitor & No
- [11.28] Lamotrigine & Topiramate — Broad-Spectrum Antiepileptics, Bipolar Mood Stabiliser & Migraine
