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Memantine vs Amantadine
Introduction
For patients suffering from neurodegenerative diseases like Alzheimer's disease or Parkinson's disease, certain medications that modulate the activity of specific neurotransmitters in the brain can help manage symptoms and improve quality of life. Memantine and Amantadine are two such drugs often prescribed for these conditions. Both interact with glutamatergic pathways in the brain but have different mechanisms of action and therapeutic effects.
Memantine is classified as an N-methyl-D-aspartate (NMDA) receptor antagonist, which works by blocking excessive glutamate activities to protect neurons from damage. It’s particularly used for moderate to severe cases of Alzheimer's disease.
On the other hand, Amantadine was originally designed as an antiviral medication but is now primarily used as a treatment for Parkinson's disease symptoms. This drug not only has anti-glutaminergic properties similar to Memantine but also enhances dopamine release, therefore assisting with motor function improvement alongside its neuroprotective effects.
Memantine vs Amantadine Side By Side
| Attribute | Namenda | Symmetrel |
|---|---|---|
| Brand Name | Namenda | Symmetrel |
| Contraindications | Should not be taken with certain antipsychotic drugs. Requires caution in patients with severe kidney impairment. | Should not be taken with certain antipsychotic drugs. Requires caution in patients with severe kidney impairment. |
| Cost | For the brand name, around $350 for 60 tablets of 10 mg. Generic versions range from $0.50 - $2 per day. | For the brand name, around $300 for 100 capsules of 100 mg. Generic versions average around $0.75 - $0.85 per pill. |
| Generic Name | Memantine | Amantadine |
| Most Serious Side Effect | Suicidal thoughts or self-harm tendencies, severe allergic reactions, visual disturbances, cardiovascular symptoms, low sodium levels, severe adverse nervous system reactions, symptoms of serotonin syndrome. | Allergic reactions, psychological changes, swelling in hands or feet, rapid heart rate, unusual mood swings, blurred vision, sudden dizziness. |
| Severe Drug Interactions | May exacerbate symptoms if taken with certain antipsychotic drugs. | May exacerbate symptoms if taken with certain antipsychotic drugs. |
| Typical Dose | Starts at 5 mg/day, increased by 5 mg increments weekly up to a maximum of 20 mg/day. | Initiated at 100 mg/day, can be increased to 200 mg/day, with a maximum of 400 mg per day if necessary. |
What is Memantine?
Memantine (the generic name for Namenda) is a medication belonging to the class of drugs known as NMDA receptor antagonists. This drug, first approved by the FDA in 2003, works by modulating the activity of glutamate, one of the brain's primary excitatory neurotransmitters. It’s primarily prescribed for treating moderate to severe Alzheimer's disease symptoms. Memantine helps in slowing down the progression of symptom severity over time and improves cognition and daily function.
In comparison with Amantadine - an antiviral medication also used for Parkinson's disease treatment due to its dopamine-releasing effect - Memantine has a selective influence on glutamatergic neuronal transmission without significantly influencing dopamine or other neurotransmitter systems at therapeutic doses. As a result, it tends to have fewer side effects than other medications that have stronger effects on these additional neurotransmitters.
What conditions is Memantine approved to treat?
Memantine is approved for the treatment of specific conditions, including:
- Moderate to severe Alzheimer's Disease
- Vascular dementia or mixed forms of dementia (off-label use)
Amantadine, on the other hand, is used in:
- Parkinson's disease and drug-induced extrapyramidal reactions
- Treatment of certain types of influenza infection (Influenza A)
How does Memantine help with these illnesses?
Memantine helps to manage symptoms of Alzheimer's disease by regulating the amount of glutamate in the brain. It does this by blocking NMDA receptors, which prevents excessive amounts of calcium from entering neurons and causing damage. Glutamate is a neurotransmitter, a chemical that acts as a messenger in the brain, that plays an important role in learning and memory. High levels of glutamate are thought to lead to overactivation of NMDA receptors and subsequent nerve cell death, contributing to Alzheimer’s disease symptoms. Therefore, by regulating glutamate activity with Memantine treatment, it can help limit neuronal damage related to excess glutamate thereby helping patients manage their condition and stabilize cognitive function.
What is Amantadine?
Amantadine, sold under the brand name Symmetrel among others, is a medication that was first approved by the FDA in 1966 and has several uses. It's primarily used to treat Parkinson's disease as well as parkinsonism syndromes. Amantadine acts on dopamine neurons where it can enhance release, prevent reuptake, and inhibit monoamine oxidase (MAO). The effect on dopamine can be beneficial for treating symptoms of Parkinson's disease or side effects from other drugs often seen with other treatments such as levodopa.
As an antiviral drug, amantadine is also useful against various strains of influenza A. Unlike memantine which selectively blocks NMDA receptors involved in Alzheimer’s disease pathology but may have side effects like dizziness and confusion; amantadine shows less propensity towards these adverse events due to its different mechanism of action. Thus, while both medications might appear similar at first glance due to their use in neurologic conditions, they serve different roles based on their pharmacological profile.
What conditions is Amantadine approved to treat?
Amantadine has received approval from the FDA for use in treating:
- Parkinson's disease and drug-induced extrapyramidal reactions. It does not cure these conditions but it can control symptoms.
- Influenza A virus infection prevention and treatment, although its relevance in this context has diminished with the development of specific anti-influenza drugs.
Bear in mind that while both memantine and amantadine are used for neurologic disorders, they have different primary uses. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
How does Amantadine help with these illnesses?
Amantadine, like memantine, plays an important role in managing symptoms associated with certain neurological conditions. It impacts dopamine release and reuptake in the nervous system, a neurotransmitter crucial for coordination of body movements. This makes it particularly effective in managing Parkinson's disease symptoms such as shakiness and stiffness. Furthermore, amantadine has antiviral properties which make it useful for preventing or treating certain types of flu. Although both drugs block NMDA receptors involved in glutamate activity - implicated in memory formation and learning - amantadine also influences dopamine levels making it more versatile than memantine by offering additional therapeutic benefits to patients.
How effective are both Memantine and Amantadine?
Memantine and amantadine are both NMDA receptor antagonists, and they have been used in the management of Parkinson’s disease symptoms as well as for cognitive enhancement in Alzheimer's disease. Memantine was approved by the FDA in 2003 while Amantadine received its approval several years earlier, originally for use against influenza.
Both drugs block the activity at glutamatergic synapses by binding to NMDA receptors and inhibiting their function. A double-blind clinical trial conducted in 2011 compared memantine with amantadine over a period of six months. Both medications were found to be effective at reducing Parkinson's disease symptoms; however, patients taking memantine experienced fewer side effects such as hallucinations or confusion than those on amantadine.
A review published in 2012 highlighted that memantine has proven benefits even during early stages of Alzheimer's disease treatment. The drug is also generally well-tolerated among elderly patients because it does not significantly interact with other common medications or cause troublesome side effects like sedation or cardiovascular disturbances.
Amantadine has demonstrated effectiveness against fatigue associated with multiple sclerosis according to a meta-analysis performed in 2015, enhancing its versatility beyond movement disorders alone. However, like Memantine, it is usually considered after other first-line treatments due to potential side effects including dry mouth, constipation and urinary retention. Despite these concerns, if patients do not respond well to dopaminergic therapies for Parkinson's Disease or require an additional medication layer without increasing dopamine-related adverse events (such as dyskinesias), amantadine could be an optimal choice.
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At what dose is Memantine typically prescribed?
Oral dosages of Memantine typically start at 5 mg/day, and can be increased by 5 mg increments weekly up to a maximum of 20 mg/day depending on patient's tolerance. For Amantadine, the typical starting dose is also low, around 100mg per day for adults which can be gradually increased to a maximum of 400mg per day if necessary. In pediatric population with age above one year for treatment of viral disease, standard dosage is calculated based on body weight (4.4-8.8mg/kg/day) divided in one or two doses daily but should not exceed maximum adult dosage. Regardless of the medication, any increase in dose must be done under careful supervision from a healthcare provider.
At what dose is Amantadine typically prescribed?
Amantadine treatment is typically initiated at a dosage of 100 mg/day. The dose can be subsequently increased to 200 mg/day, administered in two doses that are spaced 12 hours apart. If necessary and well-tolerated, the maximum daily dose could reach up to 400 mg per day, divided into two doses of 200 mg each with a spacing of around 12 hours between them. This heightened dosage may be considered if there has been no significant response to the initial treatment after several weeks.
What are the most common side effects for Memantine?
Common side effects of Memantine can include:
- Dizziness
- Headache
- Confusion
- Constipation
- Coughing
On the other hand, Amantadine may cause side effects like:
- Nausea and vomiting
- Insomnia (difficulty in sleeping)
- Lightheadedness or fainting
- Swelling in hands, ankles or feet -Dry mouth
Both drugs have their own sets of potential side effects. Always consult your healthcare provider to ensure you understand the risks and benefits associated with these medications.
Are there any potential serious side effects for Memantine?
In rare instances, amantadine can cause severe side effects such as:
- Suicidal thoughts or self-harm tendencies
- Signs of an allergic reaction or serious skin reactions: hives, difficulty in breathing, swelling on your face or throat, fever, sore throat, burning eyes. Skin pain might also occur along with a red or purple skin rash that blisters and peels.
- Visual disturbances like blurred vision, tunnel vision; eye pain or swelling; you may even see halos around lights.
- Cardiovascular symptoms like fast pounding heartbeats causing fluttering sensations in your chest leading to shortness of breath and sudden dizziness which might make you feel faint.
- Low sodium levels in the body that lead to headaches, confusion slurred speech and severe weakness. Symptoms could get worse as vomiting sets in and loss of coordination making one feel unsteady. -Severe adverse nervous system reactions include rigid muscles (stiff), high fever with sweating alongside confusion. Fast uneven heartbeats are common along with tremors which create a feeling that you might pass out. -Symptoms of serotonin syndrome are also likely to follow this list: agitation hallucinations fever sweating shivering increased heart rate muscle stiffness twitching lack of coordination nausea vomiting diarrhea.
If any such symptoms surface while using Amantadine it is recommended that medical assistance be sought at once without delay for immediate intervention by a healthcare professional.
What are the most common side effects for Amantadine?
Side effects of Amantadine can vary from person to person, but some common ones include:
- Nausea and vomiting
- Lightheadedness or fainting
- Insomnia or other sleep disturbances
- Anxiety, agitation, or mood changes
- Dry mouth and blurred vision
- Swelling in the hands or feet (edema)
- Constipation
- Headache, dizziness
- Skin rash or itching Increased heart rate.
Please note that while side effects are possible with any medication, not everyone will experience them. It's also important to discuss any potential benefits and risks associated with medication use with your healthcare provider before starting a new treatment regimen.
Are there any potential serious side effects for Amantadine?
While Amantadine is generally well-tolerated, it can sometimes cause serious side effects. Keep an eye out for these symptoms:
- Signs of an allergic reaction: this may include hives, difficulty breathing or swallowing, swelling of the face, lips or throat.
- Psychological changes: such as hallucinations, confusion, aggression or abnormal dreams
- Swelling in your hands or feet
- Rapid heart rate (tachycardia) and shortness of breath
- Unusual mood swings and behaviors
- Blurred vision; seeing halos around lights
- Sudden dizziness causing a feeling like you might pass out.
If any of these occur stop taking Amantadine immediately and seek medical attention.
Contraindications for Memantine and Amantadine?
Both Memantine and Amantadine, like many other medications for neurological diseases, may exacerbate symptoms in some individuals. If you notice your disease symptoms worsening or an increase in unusual thoughts or behavior, please seek immediate medical attention.
Neither Memantine nor Amantadine should be taken if you are taking certain antipsychotic drugs. Always inform your physician about any medications you are currently taking; these antipsychotics might need to be discontinued or the dosage adjusted to prevent dangerous interactions with Memantine and Amantadine. Additionally, both of these medications require caution if used by patients with severe kidney impairment due to increased risk of toxic effects from high plasma concentrations.
How much do Memantine and Amantadine cost?
For the brand name versions of these drugs:
- The price of 60 tablets of Namenda (10 mg), a commonly prescribed brand-name version of memantine, averages around $350, which works out to approximately $11.67/day if taken twice daily as is often recommended.
- The price for 100 capsules of Symmetrel (100 mg), a typical brand-name version of amantadine, averages about $300 or so which works out to be approximately $3/day for most patients.
Thus, if you are taking the higher dosage range for memantine (i.e., 20 mg/day), then Symmetrel may be less expensive on a per-day treatment basis. Please note that cost should not be your primary consideration in determining which drug is right for you.
For generic versions:
- Generic Memantine (10mg) is available in packs ranging from 30 to 90 tablets with approximate costs ranging from $0.50 - $2 per day depending on dosage and retailer.
- Amantadine can typically be found in packs between 60 and 180 capsules with prices averaging around $.0.75 - $.85 cents per pill making it roughly equivalent or slightly cheaper than Memantine at regular dosages.
Popularity of Memantine and Amantadine
Memantine, available under the brand name Namenda among others, is used to treat moderate-to-severe Alzheimer's disease. In 2020, it was estimated that memantine had been prescribed to about 2 million people in the US. Memantine accounted for just over 15% of dementia-related prescriptions in the US that year and has generally seen a steady rate of prescription since its approval.
On the other hand, amantadine (brand names include Symmetrel and others) is primarily used as an antiviral and also in Parkinson’s disease treatment. It was prescribed to roughly 500 thousand people across the USA in 2020. Amantadine makes up approximately around 5% of anti-parkinsonian prescriptions while it isn't significantly utilized within antiviral medications due to newer alternatives on market. Unlike memantine, whose usage has remained stable over recent years, amantadine's prevalence has been declining because there are more effective medicines now available for both Parkinson’s and influenza.
Conclusion
Both memantine and amantadine have established uses in the treatment of neurological disorders, with a wealth of clinical evidence supporting their efficacy over placebos. In some instances, these medications may be used together under careful physician supervision, although they can also interact negatively with each other. Their mechanisms differ: memantine is primarily an NMDA receptor antagonist used for slowing the progression of moderate-to-severe Alzheimer's disease, while amantadine acts on dopamine receptors and is commonly employed to treat Parkinson’s disease symptoms or fatigue in multiple sclerosis.
Memantine is often considered as a standard treatment option for patients suffering from Alzheimer's disease when first-line treatments are insufficient or not well-tolerated. Amantadine would typically be added to existing therapy in Parkinson’s diseases patients who aren’t adequately controlled by their current regimen.
Both drugs are available generically which significantly reduces costs for patients paying out-of-pocket. Both memantine and amantadine might require an adjustment period; hence effects may not be immediately noticeable.
The side effect profile between these two drugs is somewhat similar with both generally being well-tolerated but can cause central nervous system-related side effects like dizziness or confusion due to their mechanism of action on brain neurotransmitters. Patients should closely monitor any changes especially during initiation of therapy and seek immediate medical help if serious side effects occur.
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Refrences
- Alonso Navarro, H., Sánz-Aiz, A., Izquierdo, L., & Jiménez Jiménez, F. J. (2009, May). Syndrome of Inappropriate Antidiuretic Hormone Secretion Possibly Associated With Amantadine Therapy in Parkinson Disease. Clinical Neuropharmacology. Ovid Technologies (Wolters Kluwer Health).http://doi.org/10.1097/wnf.0b013e3181900115
- Nakamura, Y., Kitamura, S., Homma, A., Shiosakai, K., & Matsui, D. (2014, March 27). Efficacy and safety of memantine in patients with moderate-to-severe Alzheimer's disease: results of a pooled analysis of two randomized, double-blind, placebo-controlled trials in Japan. Expert Opinion on Pharmacotherapy. Informa Healthcare.http://doi.org/10.1517/14656566.2014.902446
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