Namenda 10mg Tablets
It is used to treat dementia in people with Alzheimer's disease.
Drug Class
Agents for Alzheimer's Disease
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 affecting a chemical in the brain called glutamate, which is involved in learning and memory. By balancing glutamate activity, memantine can help improve memory, awareness, and the ability to perform daily activities, though it does not cure the disease.
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. It's essential to continue taking this medication as prescribed by your doctor or healthcare provider, even if you're feeling well.
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. When disposing of unused or expired medications, do not flush them down the toilet or pour them down the drain unless instructed to do so. Instead, consult with your pharmacist for guidance on the best disposal method. You may also want to explore drug take-back programs in your area.
Missing a Dose
If you miss a dose, skip it and resume your regular dosing 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. It's essential to continue taking this medication as prescribed by your doctor or healthcare provider, even if you're feeling well.
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. When disposing of unused or expired medications, do not flush them down the toilet or pour them down the drain unless instructed to do so. Instead, consult with your pharmacist for guidance on the best disposal method. You may also want to explore drug take-back programs in your area.
Missing a Dose
If you miss a dose, skip it and resume your regular dosing 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 exactly as prescribed by your doctor. Do not stop taking it without consulting your doctor.
- It can be taken with or without food.
- If you miss a dose, take it as soon as you remember, unless it's almost time for your next dose. Do not double dose.
- Keep all appointments with your doctor and the laboratory. Your doctor may order certain tests to check your response to memantine.
- Inform your doctor about all other medications, supplements, and herbal products you are taking.
- Be cautious when driving or operating machinery until you know how memantine affects you, as it can cause dizziness or confusion.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
Initial 5 mg once daily, titrated weekly by 5 mg increments to a target dose of 10 mg twice daily (20 mg/day).
Dose Range:
5 - 20 mg
Condition-Specific Dosing:
moderate to severe Alzheimer's disease:
Titrate over 4 weeks: Week 1: 5 mg once daily; Week 2: 10 mg/day (5 mg twice daily); Week 3: 15 mg/day (5 mg and 10 mg); Week 4: 20 mg/day (10 mg twice daily).
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established
Adolescent:
Not established
Dose Adjustments
Renal Impairment:
Mild:
No dosage adjustment needed (CrCl 50-80 mL/min)
Moderate:
Maximum recommended dose is 5 mg twice daily (10 mg/day) (CrCl 30-49 mL/min)
Severe:
Maximum recommended dose is 5 mg twice daily (10 mg/day) (CrCl 5-29 mL/min)
Dialysis:
Not recommended for patients with end-stage renal disease (CrCl <5 mL/min) due to lack of data and potential for accumulation.
Hepatic Impairment:
Mild:
No dosage adjustment needed
Moderate:
No dosage adjustment needed
Severe:
Use with caution; not studied in severe hepatic impairment.
Pharmacology
Mechanism of Action
Memantine is a non-competitive, moderate-affinity antagonist of N-methyl-D-aspartate (NMDA) receptors. It is thought to exert its therapeutic effect by blocking the effects of abnormally elevated tonic levels of glutamate, which may contribute to neuronal dysfunction in Alzheimer's disease, without interfering with normal physiological NMDA receptor activity.
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; affected by urinary pH (decreased clearance with alkaline urine).
ExcretionRoute:
Renal
Unchanged:
Approximately 48% (unchanged in urine)
Pharmacodynamics
OnsetOfAction:
Weeks (due to titration schedule)
PeakEffect:
Weeks (after reaching target dose)
DurationOfAction:
Maintained with continued dosing due to long half-life.
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
Although rare, this medication can cause severe and potentially life-threatening side effects. If you experience any of the following symptoms, contact your doctor or seek medical attention immediately:
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. If you experience any of the following side effects or any other unusual symptoms that bother you or do not go away, contact your doctor:
Dizziness or headache
Diarrhea or constipation
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch. Your doctor can provide medical advice about side effects and help you manage any concerns.
Although rare, this medication can cause severe and potentially life-threatening side effects. If you experience any of the following symptoms, contact your doctor or seek medical attention immediately:
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. If you experience any of the following side effects or any other unusual symptoms that bother you or do not go away, contact your doctor:
Dizziness or headache
Diarrhea or constipation
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns about side effects, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch. Your doctor can provide medical advice about side effects and help you manage any concerns.
Seek Immediate Medical Attention If You Experience:
- Severe dizziness or lightheadedness
- Worsening confusion or hallucinations
- Seizures
- Difficulty urinating or changes in urination
- Unusual bleeding or bruising
- Signs of an 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.
All medications you are currently taking, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins. This is crucial to avoid potential interactions between this medication and other substances.
* Any existing health problems, as this medication may interact with certain conditions.
To ensure your safety, it is vital to verify that it is safe to take this medication with all your current medications and health conditions. Always consult your doctor before starting, stopping, or changing the dose of any 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.
All medications you are currently taking, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins. This is crucial to avoid potential interactions between this medication and other substances.
* Any existing health problems, as this medication may interact with certain conditions.
To ensure your safety, it is vital to verify that it is safe to take this medication with all your current medications and health conditions. Always consult your doctor before starting, stopping, or changing the dose of any 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
- Seizures
- Slowed heart rate
- Weakness
- Vomiting
- Diarrhea
What to Do:
Seek immediate medical attention or call a Poison Control Center (1-800-222-1222). Bring the medication container with you.
Drug Interactions
Major Interactions
- Other NMDA antagonists (e.g., amantadine, ketamine, dextromethorphan): Concomitant use may increase the frequency and severity of adverse reactions due to additive pharmacodynamic effects.
Moderate Interactions
- Urinary alkalinizers (e.g., carbonic anhydrase inhibitors, sodium bicarbonate): May decrease the renal clearance of memantine, leading to increased plasma concentrations and potential toxicity.
- Drugs eliminated by renal tubular secretion (e.g., cimetidine, ranitidine, quinidine, nicotine): Memantine is partially eliminated by tubular secretion, and coadministration with drugs that are substrates or inhibitors of the renal cationic transport system may alter the plasma levels of both drugs.
Monitoring
Baseline Monitoring
Cognitive function assessment (e.g., MMSE, ADAS-Cog)
Rationale: To establish baseline cognitive status and assess disease severity.
Timing: Prior to initiation of therapy
Renal function (CrCl)
Rationale: To determine appropriate starting and maximum dose, especially in patients with impaired renal function.
Timing: Prior to initiation of therapy
Routine Monitoring
Cognitive function assessment
Frequency: Periodically (e.g., every 6-12 months or as clinically indicated)
Target: Stabilization or slower decline of cognitive symptoms
Action Threshold: Significant decline or lack of benefit may warrant re-evaluation of therapy.
Adverse effects monitoring (e.g., dizziness, headache, confusion, constipation, hallucinations)
Frequency: Regularly, especially during dose titration and initial weeks of therapy
Target: Tolerable side effect profile
Action Threshold: Intolerable side effects may require dose reduction or discontinuation.
Renal function (CrCl)
Frequency: Periodically, especially in elderly or those with risk factors for renal impairment
Target: Stable renal function
Action Threshold: Significant decline in CrCl may necessitate dose adjustment.
Symptom Monitoring
- Dizziness
- Headache
- Confusion
- Constipation
- Hallucinations
- Hypertension
- Somnolence
- Vomiting
Special Patient Groups
Pregnancy
Category B. Animal studies have not shown harm to the fetus, but there are no adequate and well-controlled studies in pregnant women. Use only if clearly needed.
Trimester-Specific Risks:
First Trimester:
Low risk based on animal data, but human data is limited.
Second Trimester:
Low risk based on animal data, but human data is limited.
Third Trimester:
Low risk based on animal data, but human data is limited.
Lactation
L3 (Moderate risk). Memantine is excreted into breast milk. Potential for adverse effects on the breastfed infant (e.g., CNS effects). Weigh the benefits of breastfeeding against the potential risks to the infant.
Infant Risk:
Potential for CNS effects (e.g., sedation, irritability) due to excretion into breast milk. Monitor infant for adverse effects.
Pediatric Use
Safety and effectiveness in pediatric patients have not been established. Memantine 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 should be assessed as elderly patients are more likely to have impaired renal function.
Clinical Information
Clinical Pearls
- Memantine is typically initiated with a low dose and gradually titrated up to the target dose over several weeks to minimize gastrointestinal and CNS side effects.
- It can be used as monotherapy or in combination with cholinesterase inhibitors (e.g., donepezil) for moderate to severe Alzheimer's disease.
- Patients should be monitored for cognitive improvement or stabilization, as well as for common side effects like dizziness, headache, and confusion.
- Renal function should be assessed at baseline and periodically, as dose adjustments are necessary for moderate to severe renal impairment.
- Counsel patients and caregivers that memantine helps manage symptoms but does not cure Alzheimer's disease.
Alternative Therapies
- Cholinesterase inhibitors (e.g., donepezil, rivastigmine, galantamine) - used for mild to moderate Alzheimer's disease, and donepezil for severe.
- Other symptomatic treatments for behavioral and psychological symptoms of dementia (e.g., antipsychotics, antidepressants, anxiolytics), used cautiously and off-label.
Cost & Coverage
Average Cost:
$20 - $500+ per 30 tablets (generic vs. brand)
Generic Available:
Yes
Insurance Coverage:
Tier 1 (generic) or Tier 2/3 (brand), varies by insurance plan
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 your 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 medication taken, the amount, and the time it happened.