Namenda 5mg Tablets
It is used to treat dementia in people with Alzheimer's disease.
Drug Class
N-methyl-D-aspartate (NMDA) receptor antagonist
Pharmacologic Class
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 affecting certain chemicals in the brain that are involved in memory and learning. It can help 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 bathrooms. Keep all medications in a safe location, out of 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 normal schedule. Do not take two doses at the same time or take 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 bathrooms. Keep all medications in a safe location, out of 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 normal schedule. Do not take two doses at the same time or take 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. Do not stop taking it without consulting your doctor.
- Memantine tablets can be taken with or without food.
- If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take two doses at once.
- Do not crush, chew, or break the extended-release capsules (Namenda XR). Swallow them whole.
- Report any new or worsening side effects to your doctor.
- Maintain regular follow-up appointments with your healthcare provider to monitor your condition and treatment effectiveness.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
5 mg once daily, titrated weekly to a target maintenance dose of 20 mg once daily.
Dose Range:
5 - 20 mg
Condition-Specific Dosing:
Alzheimer's Disease (moderate to severe):
Initial: 5 mg once daily. Titrate weekly by 5 mg increments to 10 mg/day (5 mg BID), 15 mg/day (5 mg AM, 10 mg PM), and 20 mg/day (10 mg BID).
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 once daily (CrCl 30-49 mL/min).
Severe:
Maximum recommended dose is 5 mg once daily (CrCl <30 mL/min).
Dialysis:
Not specifically studied, but likely requires significant dose reduction or avoidance due to renal excretion.
Hepatic Impairment:
Mild:
No dosage adjustment necessary.
Moderate:
No dosage adjustment necessary.
Severe:
Not studied; use with caution.
Pharmacology
Mechanism of Action
Memantine is a non-competitive (uncompetitive) N-methyl-D-aspartate (NMDA) receptor antagonist. It binds to the NMDA receptor-operated cation channels with moderate affinity and voltage-dependency. It blocks the effects of abnormal, sustained activation of NMDA receptors by glutamate, which is thought to contribute to the pathophysiology of Alzheimer's disease, while allowing for normal physiological activation of the receptors.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 100%
Tmax:
3 to 7 hours
FoodEffect:
Food has no effect on the absorption of memantine.
Distribution:
Vd:
9-11 L/kg
ProteinBinding:
Approximately 45%
CnssPenetration:
Yes
Elimination:
HalfLife:
60 to 80 hours
Clearance:
Renal clearance is approximately 170 mL/min/1.73 m²
ExcretionRoute:
Renal (primarily unchanged)
Unchanged:
Approximately 48% of the administered dose is excreted unchanged in urine.
Pharmacodynamics
OnsetOfAction:
Gradual (titration period)
PeakEffect:
Weeks (after reaching maintenance dose)
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
- 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
- Headache
- Diarrhea
- Constipation
Reporting Side Effects
This list does not include all possible side effects. If you have questions or concerns about side effects, consult your doctor. For medical advice about side effects, you can also contact your doctor. Additionally, you can 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
- 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
- Headache
- Diarrhea
- Constipation
Reporting Side Effects
This list does not include all possible side effects. If you have questions or concerns about side effects, consult your doctor. For medical advice about side effects, you can also contact your doctor. Additionally, you can 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 lightheadedness
- Severe headache
- Worsening confusion or agitation
- Hallucinations (seeing or hearing things that are not there)
- Difficulty breathing or swallowing
- Unusual weakness or tiredness
- Signs of a severe allergic reaction (rash, itching/swelling, severe dizziness, trouble breathing)
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.
Potential interactions with other medications or health conditions. This medication may affect or be affected by other drugs or health problems, so it is crucial to disclose all relevant information.
To ensure safe treatment, provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Natural products and vitamins you are using
* Any existing health problems or conditions
Before making any changes to your medication regimen, including starting, stopping, or adjusting the dose of any drug, consult with your doctor to confirm that it is safe to do so in conjunction with this medication.
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.
Potential interactions with other medications or health conditions. This medication may affect or be affected by other drugs or health problems, so it is crucial to disclose all relevant information.
To ensure safe treatment, provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Natural products and vitamins you are using
* Any existing health problems or conditions
Before making any changes to your medication regimen, including starting, stopping, or adjusting the dose of any drug, consult with your doctor to confirm that it is safe to do so in conjunction with this medication.
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, you must discuss this with your doctor. This conversation will help you understand the benefits and risks of taking this drug, both for you and your baby, allowing you to make an informed decision.
Overdose Information
Overdose Symptoms:
- Severe dizziness
- Agitation
- Confusion
- Hallucinations
- Restlessness
- Slowed heart rate
- Weakness
- Vomiting
- Diarrhea
- Unconsciousness
What to Do:
In case of suspected overdose, seek immediate medical attention or call a Poison Control Center at 1-800-222-1222. Bring the medication bottle with you.
Drug Interactions
Moderate Interactions
- Drugs that are renally eliminated via active tubular secretion (e.g., cimetidine, ranitidine, quinidine, nicotine, procainamide): May increase memantine plasma levels.
- Carbonic anhydrase inhibitors (e.g., acetazolamide, dichlorphenamide, methazolamide) and sodium bicarbonate: May decrease memantine renal clearance, leading to increased plasma levels and potential toxicity.
Monitoring
Baseline Monitoring
Cognitive function assessment (e.g., MMSE, ADAS-Cog)
Rationale: To establish baseline severity of Alzheimer's disease and monitor treatment efficacy.
Timing: Prior to initiation of therapy
Renal function (CrCl)
Rationale: To guide initial dosing and dose adjustments in patients with renal impairment.
Timing: Prior to initiation of therapy
Routine Monitoring
Cognitive function assessment
Frequency: Periodically (e.g., every 6-12 months or as clinically indicated)
Target: Improvement or stabilization of cognitive decline
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.
Behavioral symptoms
Frequency: Regularly
Target: Improvement or stabilization of behavioral symptoms associated with AD
Action Threshold: Worsening or new behavioral issues may require intervention.
Symptom Monitoring
- Dizziness
- Headache
- Confusion
- Constipation
- Diarrhea
- Hallucinations
- Cough
- Vomiting
- Back pain
- Fatigue
Special Patient Groups
Pregnancy
Memantine is classified as Pregnancy Category B. Animal studies have shown no evidence of teratogenicity or adverse effects on fetal development at clinically relevant doses. However, 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:
Low risk based on animal data, but human data are lacking.
Second Trimester:
Low risk based on animal data, but human data are lacking.
Third Trimester:
Low risk based on animal data, but human data are lacking.
Lactation
Memantine is excreted in human milk. The amount of memantine transferred to breast milk is low, and the potential for adverse effects on a breastfed infant appears to be low. However, caution should be exercised, and the benefits of breastfeeding should be weighed against the potential risks to the infant.
Infant Risk:
L3 (Moderately safe; limited data suggest low risk, but potential for minor adverse effects or accumulation in the infant cannot be ruled out).
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 dose adjustment is required based on age alone, but dose adjustments are necessary for age-related decline in renal function.
Clinical Information
Clinical Pearls
- Memantine is often used in combination with cholinesterase inhibitors (e.g., donepezil) for moderate to severe Alzheimer's disease.
- Titrate the dose slowly over several weeks to minimize side effects, particularly dizziness and confusion.
- Patients should be advised that memantine is not a cure for Alzheimer's disease but may help manage symptoms and slow the rate of decline.
- Monitor for changes in cognitive function, behavior, and functional abilities regularly.
- Ensure patients and caregivers understand the importance of adherence to the dosing schedule.
Alternative Therapies
- Cholinesterase inhibitors (e.g., donepezil, rivastigmine, galantamine) for mild to moderate Alzheimer's disease or in combination with memantine for moderate to severe disease.
Cost & Coverage
Average Cost:
Varies widely, typically $10-$50 for generic 5mg x 30 tablets per 30 tablets
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 for generic; Tier 3 or higher for brand-name
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 emergency medical attention. When seeking help, be prepared to provide details about the overdose, including the medication taken, the amount, and the time it occurred.