Memantine 5mg Tablets
It is used to treat dementia in people with Alzheimer's disease.
Drug Class
Anti-Alzheimer's agent
Pharmacologic Class
N-methyl-D-aspartate (NMDA) receptor antagonist
Pregnancy Category
Category B
FDA Approved
Oct 2003
DEA Schedule
Not Controlled
Overview
What is this medicine?
Memantine is a medication used to treat moderate to severe Alzheimer's disease. It works by helping to restore the balance of certain natural substances in the brain, which can improve memory, awareness, and the ability to perform daily activities.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication as directed, with or without food. Continue taking it even if you feel well, unless your doctor or healthcare provider advises you to stop.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, avoiding the bathroom. Keep all medications in a safe location, out of the reach of children and pets. Dispose of unused or expired medications properly. Do not flush them down the toilet or pour them down the drain unless instructed to do so. If you have questions about disposal, consult your pharmacist. You may also want to check if there are drug take-back programs in your area.
Missing a Dose
If you miss a dose, skip it and resume your regular schedule. Do not take two doses at the same time or extra doses. If you miss taking your medication for several days in a row, contact your doctor before restarting your medication regimen.
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication as directed, with or without food. Continue taking it even if you feel well, unless your doctor or healthcare provider advises you to stop.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, avoiding the bathroom. Keep all medications in a safe location, out of the reach of children and pets. Dispose of unused or expired medications properly. Do not flush them down the toilet or pour them down the drain unless instructed to do so. If you have questions about disposal, consult your pharmacist. You may also want to check if there are drug take-back programs in your area.
Missing a Dose
If you miss a dose, skip it and resume your regular schedule. Do not take two doses at the same time or extra doses. If you miss taking your medication for several days in a row, contact your doctor before restarting your medication regimen.
Lifestyle & Tips
- Take memantine exactly as prescribed by your doctor, usually once or twice a day.
- It can be taken with or without food.
- Do not crush, chew, or break the tablets. If using the oral solution, use the provided dosing device.
- Do not stop taking memantine suddenly without consulting your doctor, as this may worsen symptoms.
- Continue with other prescribed treatments and therapies for Alzheimer's disease as directed by your healthcare provider.
- Maintain a healthy lifestyle, including a balanced diet, regular exercise (as appropriate), and mental stimulation.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
Initial: 5 mg once daily. Titrate weekly by 5 mg/day to a target maintenance dose of 10 mg twice daily (20 mg/day).
Dose Range:
5 - 20 mg
Condition-Specific Dosing:
moderate to severe Alzheimer's disease:
Initial: 5 mg once daily. Titrate weekly by 5 mg/day to a target maintenance dose of 10 mg twice daily (20 mg/day).
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established
Adolescent:
Not established
Dose Adjustments
Renal Impairment:
Mild:
No dosage adjustment necessary (CrCl 50-80 mL/min).
Moderate:
Maximum recommended dose is 10 mg/day (CrCl 30-49 mL/min).
Severe:
Maximum recommended dose is 5 mg/day (CrCl 5-29 mL/min).
Dialysis:
Use with caution; not well studied in patients on dialysis. Consider 5 mg every other day or as directed by specialist.
Hepatic Impairment:
Mild:
No dosage adjustment necessary.
Moderate:
No dosage adjustment necessary.
Severe:
Use with caution; not studied in patients with severe hepatic impairment.
Pharmacology
Mechanism of Action
Memantine is a voltage-dependent, moderate-affinity uncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist. It binds to the NMDA receptor-operated cation channels, blocking the effects of abnormally elevated tonic levels of glutamate, which are thought to contribute to the neuronal dysfunction observed in Alzheimer's disease. It does not interfere with the physiological activation of NMDA receptors required for memory formation and learning.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 100%
Tmax:
3-7 hours
FoodEffect:
Food does not affect the absorption of memantine.
Distribution:
Vd:
9-11 L/kg
ProteinBinding:
Approximately 45%
CnssPenetration:
Yes
Elimination:
HalfLife:
60-80 hours
Clearance:
Primarily renal clearance, influenced by urine pH.
ExcretionRoute:
Renal
Unchanged:
Approximately 48% of the administered dose is excreted unchanged in urine.
Pharmacodynamics
OnsetOfAction:
Not precisely defined for clinical effect; steady-state concentrations reached within 7-14 days.
PeakEffect:
Clinical benefit is typically observed after several weeks of consistent dosing.
DurationOfAction:
Due to long half-life, effects persist for several days after discontinuation.
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
If you experience any of the following symptoms, call your doctor or seek medical attention immediately, as they may be signs of a severe and potentially life-threatening reaction:
- Signs of an allergic reaction, such as rash, hives, itching, red, swollen, blistered, or peeling skin (with or without fever), wheezing, tightness in the chest or throat, trouble breathing, swallowing, or talking, unusual hoarseness, or swelling of the mouth, face, lips, tongue, or throat
- Feeling confused
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. Contact your doctor if you experience any of the following side effects or if they persist or bother you:
- Dizziness or headache
- Diarrhea or constipation
Important Note: This list does not include all possible side effects. If you have questions or concerns about side effects, consult your doctor for medical advice. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
If you experience any of the following symptoms, call your doctor or seek medical attention immediately, as they may be signs of a severe and potentially life-threatening reaction:
- Signs of an allergic reaction, such as rash, hives, itching, red, swollen, blistered, or peeling skin (with or without fever), wheezing, tightness in the chest or throat, trouble breathing, swallowing, or talking, unusual hoarseness, or swelling of the mouth, face, lips, tongue, or throat
- Feeling confused
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. Contact your doctor if you experience any of the following side effects or if they persist or bother you:
- Dizziness or headache
- Diarrhea or constipation
Important Note: This list does not include all possible side effects. If you have questions or concerns about side effects, consult your doctor for medical advice. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Severe dizziness or fainting
- New or worsening confusion or hallucinations
- Seizures
- Difficulty breathing or swallowing
- Severe skin rash or allergic reaction
- Unusual changes in mood or behavior
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced as a result of the allergy.
All medications you are currently taking, including prescription and over-the-counter (OTC) medications, natural products, and vitamins. This information will help your doctor and pharmacist assess potential interactions between this medication and other substances you are taking.
* Any existing health problems, as this medication may interact with certain conditions.
To ensure your safety, it is crucial to verify that it is safe to take this medication with all your other medications and health conditions. Never start, stop, or change the dose of any medication without first consulting your doctor.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced as a result of the allergy.
All medications you are currently taking, including prescription and over-the-counter (OTC) medications, natural products, and vitamins. This information will help your doctor and pharmacist assess potential interactions between this medication and other substances you are taking.
* Any existing health problems, as this medication may interact with certain conditions.
To ensure your safety, it is crucial to verify that it is safe to take this medication with all your other medications and health conditions. Never start, stop, or change the dose of any medication without first consulting your doctor.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. If you are pregnant, planning to become pregnant, or are breast-feeding, notify your doctor immediately. You and your doctor will need to discuss the potential benefits and risks of this medication to both you and your baby to make an informed decision.
Overdose Information
Overdose Symptoms:
- Agitation
- Confusion
- Hallucinations
- Dizziness
- Somnolence
- Vertigo
- Gait disturbance
- Vomiting
- Diarrhea
- Weakness
- Seizures
- Coma
What to Do:
In case of overdose, seek immediate medical attention or call a poison control center (1-800-222-1222). Management is supportive and symptomatic. There is no specific antidote.
Drug Interactions
Moderate Interactions
- Drugs that alkalinize urine (e.g., carbonic anhydrase inhibitors, sodium bicarbonate): May decrease memantine renal clearance, leading to increased plasma levels and potential toxicity.
- Cimetidine, Ranitidine, Quinidine, Procainamide: May decrease memantine renal clearance via competition for renal tubular secretion.
- L-dopa, Dopaminergic agonists, Anticholinergics: Memantine may enhance the effects of these drugs.
- Barbiturates, Neuroleptics: Memantine may reduce the effects of these drugs.
Monitoring
Baseline Monitoring
Cognitive function assessment (e.g., MMSE, ADAS-Cog)
Rationale: To establish baseline cognitive status and severity of Alzheimer's disease.
Timing: Prior to initiation of therapy
Renal function (CrCl)
Rationale: To determine appropriate starting and maintenance doses, especially in elderly patients.
Timing: Prior to initiation of therapy
Routine Monitoring
Cognitive function and functional abilities (ADLs)
Frequency: Periodically (e.g., every 3-6 months or as clinically indicated)
Target: Stabilization or slower decline of cognitive and functional abilities
Action Threshold: Significant decline or lack of benefit may warrant re-evaluation of therapy.
Adverse effects (e.g., dizziness, headache, confusion, constipation)
Frequency: Regularly, especially during titration and dose changes
Target: Tolerable side effect profile
Action Threshold: Intolerable side effects may require dose reduction or discontinuation.
Symptom Monitoring
- Dizziness
- Headache
- Confusion
- Constipation
- Diarrhea
- Hallucinations
- Agitation
- Somnolence
- Hypertension
Special Patient Groups
Pregnancy
Memantine is classified as Pregnancy Category B. Animal studies have not shown evidence of teratogenicity, but there are no adequate and well-controlled studies in pregnant women. Use during pregnancy only if clearly needed and the potential benefits outweigh the potential risks.
Trimester-Specific Risks:
First Trimester:
No specific increased risk identified in animal studies.
Second Trimester:
No specific increased risk identified in animal studies.
Third Trimester:
No specific increased risk identified in animal studies.
Lactation
It is unknown whether memantine is excreted in human milk. Due to the potential for serious adverse reactions in breastfed infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Infant Risk:
Unknown; potential for adverse effects on the infant. Caution advised.
Pediatric Use
The safety and effectiveness of memantine in pediatric patients have not been established. It is not indicated for use in children.
Geriatric Use
Memantine is primarily used in the geriatric population for Alzheimer's disease. No specific dosage adjustment is required based solely on age, but renal function, which often declines with age, should be considered for dose adjustments.
Clinical Information
Clinical Pearls
- Memantine is often used in combination with cholinesterase inhibitors (e.g., donepezil) for moderate to severe Alzheimer's disease, as this combination may offer greater benefit than either drug alone.
- Titrate the dose slowly over several weeks to minimize gastrointestinal and CNS side effects (e.g., dizziness, confusion).
- Patients should be advised to take the medication consistently at the same time each day.
- Monitor for changes in cognitive function, behavior, and ability to perform daily activities to assess treatment effectiveness.
- Renal function is a key consideration for dosing adjustments; always check CrCl before initiating and periodically during therapy.
Alternative Therapies
- Donepezil (Aricept)
- Rivastigmine (Exelon)
- Galantamine (Razadyne)
Cost & Coverage
Average Cost:
Varies widely, typically $10-$50 for generic 5mg x 30 tablets per 30 tablets
Generic Available:
Yes
Insurance Coverage:
Generally covered by most prescription drug plans, often as a Tier 1 or Tier 2 generic.
General Drug Facts
If your symptoms or health issues persist or worsen, it's essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so be sure to check with your pharmacist for more information. If you have any questions or concerns about this medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When seeking help, be prepared to provide details about the medication, including the amount taken and the time it happened, to ensure you receive the best possible care.