Memantine 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 Antagonists
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, and continue taking it even if you feel well. It's essential to adhere to your doctor's or healthcare provider's guidance to ensure the best possible outcome.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, avoiding bathrooms and areas where children and pets can access it. Keep all medications in a safe location and dispose of unused or expired drugs properly. Do not flush medications down the toilet or pour them down the drain unless instructed to do so by your pharmacist. If you're unsure about the best way to dispose of your medication, consult your pharmacist or look into local drug take-back programs.
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 to make up for the missed one. If you miss taking your medication for several days in a row, contact your doctor before restarting your medication to ensure it's safe to do so.
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, and continue taking it even if you feel well. It's essential to adhere to your doctor's or healthcare provider's guidance to ensure the best possible outcome.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, avoiding bathrooms and areas where children and pets can access it. Keep all medications in a safe location and dispose of unused or expired drugs properly. Do not flush medications down the toilet or pour them down the drain unless instructed to do so by your pharmacist. If you're unsure about the best way to dispose of your medication, consult your pharmacist or look into local drug take-back programs.
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 to make up for the missed one. If you miss taking your medication for several days in a row, contact your doctor before restarting your medication to ensure it's safe to do so.
Lifestyle & Tips
- Take memantine 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. If it's almost time for your next dose, skip the missed dose and continue your regular schedule. Do not take two doses at once.
- Maintain regular follow-up appointments with your doctor to monitor your condition and medication effectiveness.
- Inform your doctor about all other medications, supplements, and herbal products you are taking.
- Avoid 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. 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:
moderateToSevereAlzheimersDisease:
Initial: 5 mg once daily. Increase to 5 mg twice daily, then 10 mg in the morning and 5 mg in the evening, then 10 mg twice daily. Allow at least one week between dose increases.
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 10 mg/day (CrCl 30-49 mL/min)
Severe:
Maximum recommended dose is 5 mg/day (CrCl 5-29 mL/min)
Dialysis:
Not well studied, but likely 5 mg/day or less. Administer after dialysis if possible.
Hepatic Impairment:
Mild:
No dosage adjustment needed
Moderate:
No dosage adjustment needed
Severe:
Use with caution; dosage reduction may be considered, but specific recommendations are not available.
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, preventing the prolonged influx of Ca2+ that can lead to neuronal dysfunction and death (excitotoxicity), while allowing for normal physiological activation of the receptor. This action is thought to protect neurons from excessive stimulation by glutamate, which is implicated in the pathophysiology of Alzheimer's disease.
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:
Renal clearance is pH-dependent; decreased urine pH (more acidic) increases renal clearance.
ExcretionRoute:
Renal (primarily unchanged)
Unchanged:
Approximately 48% (at neutral pH)
Pharmacodynamics
OnsetOfAction:
Gradual (therapeutic effects observed over weeks of titration)
PeakEffect:
Not acutely defined; peak therapeutic effect is achieved after reaching steady-state concentrations and optimal titration.
DurationOfAction:
Due to long half-life, effects persist with daily dosing.
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. Immediately contact your doctor or seek medical attention if you notice any of the following symptoms, which could be signs of a serious reaction:
Allergic reaction symptoms, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin (with or without fever)
+ Wheezing
+ Tightness in the chest or throat
+ Difficulty breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Confusion
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 or seek medical help if you experience any of the following side effects or if they persist or bother you:
Dizziness
Headache
Diarrhea
Constipation
Important Note
This list is not exhaustive, and you may experience other side effects not mentioned here. If you have questions or concerns about side effects, consult your doctor. For medical advice about side effects, contact your doctor.
Reporting Side Effects
You can report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. Immediately contact your doctor or seek medical attention if you notice any of the following symptoms, which could be signs of a serious reaction:
Allergic reaction symptoms, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin (with or without fever)
+ Wheezing
+ Tightness in the chest or throat
+ Difficulty breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Confusion
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 or seek medical help if you experience any of the following side effects or if they persist or bother you:
Dizziness
Headache
Diarrhea
Constipation
Important Note
This list is not exhaustive, and you may experience other side effects not mentioned here. If you have questions or concerns about side effects, consult your doctor. For medical advice about side effects, contact your doctor.
Reporting Side Effects
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
- New or worsening confusion
- Hallucinations (seeing or hearing things that are not there)
- Unusual changes in mood or behavior
- Difficulty urinating or changes in urine output
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 information will help your doctor assess 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 crucial to verify that this medication can be taken safely with all your current medications and health conditions. Never start, stop, or adjust 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) drugs, natural products, and vitamins. This information will help your doctor assess 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 crucial to verify that this medication can be taken safely with all your current medications and health conditions. Never start, stop, or adjust the dose of any medication without first consulting your doctor.
Precautions & Cautions
It is essential to inform all of 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, be sure to discuss this with your doctor. You and your doctor will need to carefully weigh the benefits and risks of using this medication to ensure the best possible outcome for both you and your baby.
Overdose Information
Overdose Symptoms:
- Agitation
- Confusion
- Dizziness
- Drowsiness
- Hallucinations
- Gait disturbance
- Vomiting
- Vertigo
- Increased excitability
- Seizures
- Coma
What to Do:
Seek immediate medical attention or call 911. Contact a poison control center at 1-800-222-1222. Treatment is supportive and symptomatic.
Drug Interactions
Major Interactions
- Other NMDA receptor antagonists (e.g., amantadine, ketamine, dextromethorphan): Concomitant use may increase the incidence and severity of adverse reactions due to additive pharmacodynamic effects.
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.
- Hydrochlorothiazide: May reduce memantine clearance, leading to increased memantine levels.
- Cimetidine, Ranitidine, Quinidine, Nicotine: Drugs eliminated by the renal cationic transport system may interact with memantine, potentially altering their plasma levels or memantine's.
Monitoring
Baseline Monitoring
Cognitive function assessment (e.g., MMSE, ADAS-Cog)
Rationale: To establish baseline severity of Alzheimer's disease and monitor therapeutic response.
Timing: Prior to initiation of therapy
Renal function (CrCl)
Rationale: To determine appropriate initial dosing and dose adjustments for patients with renal impairment.
Timing: Prior to initiation of therapy
Routine Monitoring
Cognitive function and behavioral symptoms
Frequency: Periodically (e.g., every 6-12 months or as clinically indicated)
Target: Stabilization or improvement in 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 dose titration and initial months 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 patients or those with risk factors for renal decline
Target: Stable renal function
Action Threshold: Significant decline in CrCl may necessitate memantine dose adjustment.
Symptom Monitoring
- Dizziness
- Headache
- Confusion
- Constipation
- Diarrhea
- Hallucinations
- Hypertension
- Somnolence
- Vomiting
- Cough
Special Patient Groups
Pregnancy
Memantine is Pregnancy Category B. Animal studies have not shown evidence of teratogenicity, 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 lacking.
Second Trimester:
Low risk based on animal data, but human data lacking.
Third Trimester:
Low risk based on animal data, but human data lacking.
Lactation
Memantine is excreted in the milk of lactating rats. It is unknown whether memantine is excreted in human milk. Due to the potential for serious adverse reactions in the breastfed infant, 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:
L3 (Moderate concern; no human data, but potential for accumulation due to long half-life and CNS effects).
Pediatric Use
Safety and effectiveness in pediatric patients have not been established. Not indicated for use in children.
Geriatric Use
No specific dosage adjustment is required based on age alone. However, elderly patients are more likely to have decreased renal function, which necessitates dose adjustment based on creatinine clearance.
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 like dizziness and confusion.
- Monitor for changes in cognitive function, behavior, and functional abilities to assess treatment efficacy.
- Educate patients and caregivers about the importance of adherence and potential side effects.
- Be mindful of drug interactions, especially with other NMDA antagonists or drugs that alter urine pH.
- Renal function is a key determinant for dosing; always check CrCl before initiating and periodically during therapy.
Alternative Therapies
- Cholinesterase inhibitors (e.g., Donepezil, Rivastigmine, Galantamine) - primarily for mild to moderate AD, but donepezil is also approved for severe AD.
- Supportive care and non-pharmacological interventions for behavioral symptoms.
Cost & Coverage
Average Cost:
$10 - $50 per 30 tablets (10mg)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (for 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 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.