Memantine ER 21mg Capsules
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
Jun 2010
DEA Schedule
Not Controlled
Overview
What is this medicine?
Memantine ER 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 thinking. It may help improve memory, awareness, and the ability to perform daily activities, but it is not a cure for Alzheimer's.
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 the medication with or without food, as directed. Continue taking the medication as prescribed by your doctor or healthcare provider, even if you feel well.
It's essential to swallow the medication whole; do not chew or crush it. If you notice any capsules that appear abnormal or are damaged, do not take them. If you have difficulty swallowing the medication whole, you can sprinkle the contents onto applesauce. If you choose this method, swallow the mixture immediately without chewing.
Storing and Disposing of Your Medication
Store the medication at room temperature in a dry location, avoiding bathrooms. Keep all medications in a secure place, 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 disposing of medications, consult your pharmacist. You may also want to explore drug take-back programs in your area.
What to Do If You Miss a Dose
If you miss a dose, skip it and resume your regular dosing schedule. Avoid taking two doses at the same time or taking extra doses. If you miss taking the medication for several days in a row, contact your doctor before restarting the medication.
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take the medication with or without food, as directed. Continue taking the medication as prescribed by your doctor or healthcare provider, even if you feel well.
It's essential to swallow the medication whole; do not chew or crush it. If you notice any capsules that appear abnormal or are damaged, do not take them. If you have difficulty swallowing the medication whole, you can sprinkle the contents onto applesauce. If you choose this method, swallow the mixture immediately without chewing.
Storing and Disposing of Your Medication
Store the medication at room temperature in a dry location, avoiding bathrooms. Keep all medications in a secure place, 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 disposing of medications, consult your pharmacist. You may also want to explore drug take-back programs in your area.
What to Do If You Miss a Dose
If you miss a dose, skip it and resume your regular dosing schedule. Avoid taking two doses at the same time or taking extra doses. If you miss taking the medication for several days in a row, contact your doctor before restarting the medication.
Lifestyle & Tips
- Take the capsule once daily at bedtime, with or without food.
- Swallow the capsule whole; do not chew, crush, or divide it.
- If you have trouble swallowing, you may open the capsule and sprinkle the contents on a small amount of applesauce. Swallow the mixture immediately without chewing.
- Do not stop taking memantine without consulting your doctor, as symptoms may worsen.
- Maintain regular follow-up appointments with your doctor to monitor your condition and medication effectiveness.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
Initial: 7 mg once daily. Titrate weekly by 7 mg increments to a target maintenance dose of 28 mg once daily. The 21 mg capsule is a titration step.
Dose Range:
7 - 28 mg
Condition-Specific Dosing:
moderate to severe Alzheimer's disease:
Initial: 7 mg once daily. Titrate weekly by 7 mg increments to a target maintenance dose of 28 mg once daily. Administer at bedtime.
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established
Adolescent:
Not established
Dose Adjustments
Renal Impairment:
Mild:
No dose adjustment necessary (CrCl 50-80 mL/min)
Moderate:
Maximum recommended dose is 14 mg once daily (CrCl 30-49 mL/min)
Severe:
Maximum recommended dose is 14 mg once daily (CrCl 5-29 mL/min)
Dialysis:
Not recommended for patients with end-stage renal disease (CrCl <5 mL/min) due to insufficient data.
Hepatic Impairment:
Mild:
No dose adjustment necessary
Moderate:
No dose adjustment necessary
Severe:
Use with caution; not studied in severe hepatic impairment.
Pharmacology
Mechanism of Action
Memantine is a non-competitive antagonist of N-methyl-D-aspartate (NMDA) receptors. It is believed to exert its therapeutic effect by blocking the effects of abnormally elevated tonic levels of glutamate, which may contribute to the symptoms of Alzheimer's disease, without interfering with the normal physiological activation of NMDA receptors required for learning and memory.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 100%
Tmax:
9-12 hours (for extended-release formulation)
FoodEffect:
Minimal; can be taken with or without food.
Distribution:
Vd:
9-11 L/kg
ProteinBinding:
Approximately 45%
CnssPenetration:
Yes
Elimination:
HalfLife:
60-80 hours (for extended-release formulation)
Clearance:
Primarily renal clearance
ExcretionRoute:
Renal
Unchanged:
75-90%
Pharmacodynamics
OnsetOfAction:
Gradual, due to titration schedule
PeakEffect:
Achieved after reaching maintenance dose and steady-state concentrations (typically within 2-3 weeks of reaching target dose)
DurationOfAction:
Due to long half-life, once-daily dosing provides sustained effect.
Safety & Warnings
Side Effects
Serious Side Effects: Seek Medical Help Immediately
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention right away:
- 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
- Difficulty 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 for advice:
- 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.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention right away:
- 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
- Difficulty 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 for advice:
- 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 fainting
- Severe headache
- New or worsening confusion or hallucinations
- Seizures
- Difficulty urinating or changes in urination
- 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 information will help your doctor and pharmacist identify 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) drugs, natural products, and vitamins. This information will help your doctor and pharmacist identify 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 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 currently 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:
- Severe dizziness
- Agitation
- Confusion
- Hallucinations
- Seizures
- Coma
- Bradycardia
- Vertigo
- Vomiting
- Gait disturbance
What to Do:
Seek immediate medical attention or call 911. For poison control, call 1-800-222-1222.
Drug Interactions
Major 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.
Moderate Interactions
- NMDA antagonists (e.g., amantadine, ketamine, dextromethorphan): Coadministration may lead to increased incidence and/or severity of adverse reactions due to additive pharmacodynamic effects.
- Drugs eliminated by renal tubular secretion (e.g., cimetidine, ranitidine, quinidine, procainamide): May compete with memantine for renal tubular secretion, potentially increasing memantine plasma levels.
- Anticholinergics: Possible enhanced effects of anticholinergic agents.
- Dopaminergic agonists (e.g., levodopa, bromocriptine, ropinirole): Possible enhanced effects of dopaminergic agonists.
Monitoring
Baseline Monitoring
Renal function (CrCl)
Rationale: Memantine is primarily renally eliminated; dose adjustment is required in renal impairment.
Timing: Prior to initiation of therapy.
Cognitive and functional assessment
Rationale: To establish baseline and monitor disease progression/response to therapy.
Timing: Prior to initiation.
Routine Monitoring
Cognitive and functional status
Frequency: Periodically (e.g., every 3-6 months or as clinically indicated)
Target: Stabilization or slower decline in symptoms
Action Threshold: Significant decline or lack of benefit may warrant re-evaluation of therapy.
Adverse effects (e.g., dizziness, headache, confusion, constipation, hallucinations)
Frequency: Regularly, especially during titration and dose changes
Target: Tolerable side effect profile
Action Threshold: Intolerable or severe adverse effects may require dose reduction or discontinuation.
Renal function (CrCl)
Frequency: As clinically indicated, especially if renal function changes or interacting drugs are added.
Target: Not applicable
Action Threshold: Dose adjustment if CrCl declines.
Symptom Monitoring
- Dizziness
- Headache
- Confusion
- Constipation
- Hallucinations
- Agitation
- Somnolence
- Vomiting
Special Patient Groups
Pregnancy
Memantine is Pregnancy Category B. Animal studies have shown no evidence of teratogenicity, but there are no adequate and well-controlled studies in pregnant women. Use during pregnancy only if the potential benefit justifies the potential risk to the fetus.
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 human breast milk. The amount of memantine excreted into breast milk is unknown, and the effects on a breastfed infant are also unknown. The decision to discontinue breastfeeding or discontinue the drug should take into account the importance of the drug to the mother.
Infant Risk:
L3 (Limited data â possible risk). Monitor infant for potential adverse effects such as sedation, irritability, or feeding difficulties.
Pediatric Use
Safety and effectiveness in pediatric patients have not been established. Memantine is not indicated for use in pediatric patients.
Geriatric Use
No specific dose adjustment is required based solely on age. However, geriatric patients are more likely to have decreased renal function, which necessitates dose adjustment based on creatinine clearance.
Clinical Information
Clinical Pearls
- Memantine ER is typically taken once daily at bedtime to help manage potential side effects like dizziness.
- The extended-release formulation allows for once-daily dosing, improving patient adherence compared to immediate-release formulations.
- Titration is crucial to minimize adverse effects. Patients should be started on the lowest dose and gradually increased.
- Memantine can be used alone or in combination with cholinesterase inhibitors (e.g., donepezil) for moderate to severe Alzheimer's disease.
- It is important to manage underlying conditions that can affect urine pH (e.g., urinary tract infections, renal tubular acidosis) as these can impact memantine clearance.
Alternative Therapies
- Donepezil (Aricept)
- Rivastigmine (Exelon)
- Galantamine (Razadyne)
Cost & Coverage
Average Cost:
$30 - $150 per 30 capsules (generic 28mg ER)
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 promptly. 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 details. If you have any questions or concerns about this medication, don't hesitate to discuss them with 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 information about what was taken, the amount, and the time it occurred.