Rimantadine vs Symmetrel

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Introduction

For patients dealing with influenza A viruses, certain antiviral drugs can help manage symptoms and speed up recovery. Rimantadine and Symmetrel (also known as Amantadine) are two such medications commonly prescribed for this purpose. They work by inhibiting the replication of the virus in cells, thus reducing the severity and duration of flu symptoms. Rimantadine is a derivative of Symmetrel but offers a more targeted approach to binding sites on viral proteins, thereby potentially causing fewer side effects. On the other hand, Symmetrel has additional uses beyond influenza treatment; it's used in treating Parkinson's disease due to its activity on dopamine receptors in the brain.

What is Rimantadine?

Rimantadine (also known as Flumadine) was one of the first antivirals developed to combat influenza A, marking a significant advance over the previous class of drugs. Rimantadine was approved by the FDA in 1993 and works by inhibiting viral replication, effectively preventing the virus from multiplying inside host cells. It is prescribed for prevention and treatment of certain strains of influenza A in adults.

On the other hand, Symmetrel (generic name Amantadine), while also an antiviral medication, has been repurposed for use in Parkinson's disease due to its ability to increase dopamine levels. Like Rimantadine, it has activity against influenza A viruses but it also influences dopamine release and reuptake in neurons resulting in fewer motor symptoms in Parkinson's patients. As such, Symmetrel may have more side effects related to this additional neurotransmitter activity compared with Rimantadine which primarily targets viral proteins.

What conditions is Rimantadine approved to treat?

Rimantadine is approved for the treatment of different conditions, such as:

Influenza A virus infection in adults
Prophylaxis against influenza A virus infection in adults and children aged one year or more.

Symmetrel (also known as Amantadine) is also used to treat similar conditions but has additional uses including:

Parkinson's disease symptoms
Drug-induced extrapyramidal reactions

How does Rimantadine help with these illnesses?

Rimantadine acts to control influenza by blocking the function of the viral M2 protein, which is a critical component in the virus's ability to replicate. This protein forms an ion channel that allows protons to flow into the inside of the virion. By disrupting this process, rimantadine prevents uncoating and thereby hampers replication of influenza A viruses within cells. Symmetrel (Amantadine), its predecessor, works on similar lines but has more side effects such as dizziness, insomnia and nausea due to its interaction with other receptors apart from M2 in brain tissues. Both drugs are used for prophylaxis against influenza infections but have seen decline in their usage because many strains of the influenza virus developed resistance against these medications.

What is Symmetrel?

Symmetrel, the brand name for Amantadine, is an antiviral medication that was initially approved by the FDA in 1966. It works by inhibiting the replication of certain viruses within cells and has been used to prevent or treat infections of influenza A virus. Furthermore, Symmetrel is a dopamine agonist which means it can mimic or enhance the action of dopamine in the brain. This makes it useful in treating Parkinson's disease and similar conditions where there is a deficiency of dopamine.

Unlike Rimantadine, another antiviral that also targets influenza A but lacks dopaminergic activity, Symmetrel does not solely act on viral replication but also impacts neurotransmitter levels within the nervous system. Thus its side-effect profile differs from other purely antiviral drugs such as Rimantadine: besides potential gastrointestinal upset common with many medications, Symmetrel may cause insomnia or even hallucinations due to its effect on dopamine pathways. However, this dopaminergic activity can make Symmetrel beneficial for managing symptoms in patients who suffer from both Influenza A infection and Parkinsonism.

What conditions is Symmetrel approved to treat?

Symmetrel, also known by its generic name Amantadine, is an antiviral medication endorsed for the treatment of:

Influenza A virus infection
Parkinson's disease and drug-induced extrapyramidal symptoms

This makes it a versatile option in combating not only viral infections but also neurological conditions.

How does Symmetrel help with these illnesses?

Symmetrel, also known as amantadine, is an antiviral medication that works by blocking the actions of viruses in your body. This makes it highly effective in treating and preventing certain strains of influenza A, as well as some symptoms of Parkinson's disease. Symmetrel has a dual action mechanism: it inhibits viral replication and modulates dopamine levels in the brain which helps reduce motor dysfunction seen in conditions like Parkinson's disease. Much like Wellbutrin's effects on norepinephrine, Symmetrel increases the amount of dopamine available to neurons thereby alleviating movement-related issues. On comparison with Rimantadine, another antiviral drug used to treat influenza A virus infections; Symmetrel stands out due to its added benefits for patients with Parkinson’s disease or similar conditions linked to low dopamine levels - a feature not shared by Rimantadine.

How effective are both Rimantadine and Symmetrel?

Both rimantadine and amantadine (Symmetrel) have established histories of success in treating and preventing influenza A virus infections. Rimantadine was approved by the FDA about 20 years after amantadine, but both have similar mechanisms of action as they inhibit viral replication.

The effectiveness of rimantadine and amantadine in treating influenza A was directly studied in several trials; the two drugs exhibited similar efficacy in managing symptoms as well as promising safety profiles. Studies showed no significant difference between patients receiving rimantadine or those receiving amantadine in terms of reduction of fever or alleviation of respiratory symptoms.

A 2001 meta-analysis reported that rimantidine is effective from the first day of treatment, its side effect profile is more favorable than many other antiviral medications due to lesser central nervous system side effects compared to Symmetrel, making it better tolerated especially among elderly populations.

In a systematic review published in 2016, there's evidence suggesting that while both are effective against Influenza A viruses, resistance may develop rapidly with either drug if used for an extended period. Amatandie (Symmetrel), though slightly older has been repurposed for use also in Parkinson’s disease due to its dopaminergic properties. However, because these drugs share a common mechanism on the same target protein M2 ion channel using them together would not likely offer additional benefits over monotherapy.

abstract image of a researcher studying a bottle of drug.

At what dose is Rimantadine typically prescribed?

Oral dosages of Rimantadine for adults typically start at 100 mg twice a day, and this is usually sufficient for prophylaxis against influenza A virus. For children aged 1 to 9 years old, the recommended dosage is 5 mg/kg per day in two divided doses. Adolescents aged 10-16 years may take the adult dose. In either population, if there's no response after a few days or if symptoms persist, medical advice should be sought again. The maximum dosage that should not be exceeded in any case is 200 mg/day.

Note: Symmetrel (Amantadine) has been replaced by its successor drug Rimantadine due to better side effect profiles and similar efficacy.

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At what dose is Symmetrel typically prescribed?

Symmetrel treatment is typically initiated at a dosage of 100 mg per day. If tolerated, the dose can be increased to 200 mg/day, divided into two doses, taken 12 hours apart. For some patients, the maximum recommended dose may reach up to 400 mg/day divided into two doses of 200 mg each and spaced evenly throughout the day. This higher dose may be considered if there is no response or inadequate response to treatment at the lower dosage levels after several weeks. As with all medication regimens, adherence and regular follow-up with your healthcare provider are essential for optimal results.

What are the most common side effects for Rimantadine?

Common side effects of Rimantadine can include:

Nausea and vomiting
Dizziness, nervousness and insomnia
Dry mouth
Difficulty concentrating
Headache
Loss of appetite (anorexia)
Fatigue or asthenia (general weakness)
Diarrhea

While Symmetrel also have similar side effects such as:

Nausea, constipation, diarrhea
Dizziness, lightheadedness
Insomnia or anxiety
Ataxia (loss of control over body movements)
Tremor
Dry mouth or nose
Swelling of ankles or feet.

Remember that it's important to communicate with your healthcare provider about any adverse reactions you experience while on these medications.

abstract image of a patient experiencing side effect

Are there any potential serious side effects for Rimantadine?

While both Rimantadine and Symmetrel are antiviral medications used to prevent or treat certain influenza viruses, they might cause different side effects. Using Rimantadine might lead to:

Difficulty with concentration or unusual thoughts/behavior
Signs of allergic reaction such as hives, difficulty breathing, swelling in your face or throat.
Vision changes like blurred vision, eye redness/swelling/pain
Increased heart rate or feeling lightheaded upon standing up swiftly
Symptoms of electrolyte imbalance - severe drowsiness, muscle weakness/twitching, loss of appetite accompanied by nausea/vomiting
Severe nervous system reaction - extreme excitement/nervousness/anxiety/agitation/restlessness

On the other hand, using Symmetrel could result in:

Mood swings leading to suicidal thoughts Symptoms indicative of an allergic reaction: rash/hives/itching; red/swollen/blistered/peeling skin; tightness in chest/throat; trouble breathing/swallowing/talking; unusual hoarseness; swelling in mouth/face/lips/tongue/throat. Vision disturbances including blurred vision/double vision Arrhythmia (abnormal heartbeat) Low sodium levels presenting as headache/confusion/slurred speech/severe weakness/vomiting/excessive tiredness/muscle cramps/spasms/unsteady walking.

If you experience any serious side effects from either medication, it's crucial that you seek immediate medical attention.

What are the most common side effects for Symmetrel?

Symmetrel, also known as Amantadine, can have a unique set of side effects which differentiates it from Rimantadine. These may include:

Dry mouth or throat
Blurred vision
Nausea and stomach upset
Difficulty sleeping
Anxiety and nervousness
Dizziness and headache
Some users may experience increased urination or sweating.

More severe but less common side effects could include a rash, fast heartbeat, tremors, or even feelings of confusion or agitation. In rare cases, Symmetrel might lead to muscle pain or joint discomfort. It's important to note that while weight loss isn't typically associated directly with Symmetrel use itself, some people might experience changes in appetite that could impact their weight. Remember everyone reacts differently to medication; what one person experiences another might not.

Are there any potential serious side effects for Symmetrel?

While Symmetrel (Amantadine) is generally well-tolerated, there can be potential side effects that require immediate medical attention. These may include:

Signs of an allergic reaction such as hives, difficulty breathing or swallowing, swelling in your face or throat
Severe skin reactions including a red or purple skin rash that spreads and causes blistering and peeling
Hallucinations, aggressive behavior or thoughts about self-harm.
Unusual changes in mood or mental state like confusion and disorientation
Vision problems such as blurred vision, swollen eyes, pain in the eye area or seeing halos around lights
Irregular heartbeat which could be fast-paced
Symptoms of heart failure like shortness of breath, swelling ankles/feet
Neurological issues with symptoms similar to Parkinson's disease; shakiness (tremors), unsteady walk/gait

If you experience any of these adverse effects while taking Symmetrel , it’s crucial that you stop using the medication and seek medical help immediately.

Contraindications for Rimantadine and Symmetrel?

Both Rimantadine and Symmetrel (Amantadine), along with most other antiviral medications, may worsen certain medical conditions in some people. If you notice any worsening of symptoms, such as mood changes, difficulty urinating or an increase in hallucinations or confusion, please seek immediate medical attention.

Neither Rimantadine nor Symmetrel should be taken if you are taking or have recently been taking live influenza virus vaccine. Always inform your doctor about all the medications that you're currently on; this is because there needs to be a sufficient interval between the administration of live influenza virus vaccine and initiation of antiviral treatment to avoid potential interactions.

How much do Rimantadine and Symmetrel cost?

For the brand name version of these drugs, the price comparison is as follows:

The cost for 60 tablets of Rimantadine (100 mg) averages around $250, which works out to about $4.15-$8.30/day depending on your dose.
The cost for 100 capsules of Symmetrel (Amantadine, 100 mg) averages around $350 or approximately $3.50/day.

Thus, if you are in the higher dosage range for Rimantadine (i.e., 200 mg/day), then brand-name Symmetrel could be less expensive on a per-day treatment basis. Nonetheless, remember that cost should not be your primary consideration when determining which drug is right for you.

On the other hand, costs are significantly lower for their generic versions:

Generic Amantadine (Symmetrel's active ingredient) is available in packs of 30 capsules and above with approximate costs ranging from $0.40 to $0.70 per day at dosages between 100 to 300 mg/day.
Generic rimantadine isn't readily available in many places; however when it can be found its price tends towards being higher than amantadine due to lesser market availability and production rates.

Keep in mind that prices may vary depending upon location and whether you have insurance coverage or not.

Popularity of Rimantadine and Symmetrel

Rimantadine, available as a generic medication and also under the brand name Flumadine, is an antiviral drug used in the prevention and treatment of influenza A. In 2020, Rimantadine was prescribed to about 2 million people in the US. The use of Rimantadine has seen a rise since 2013 due to increased awareness of flu prevention measures.

Amantadine, known by its brand name Symmetrel among others, is another antiviral that can be used for influenza A treatment and Parkinson's disease management. In 2020 it was estimated that Amantadine was prescribed to approximately 1.5 million individuals in the USA. Similar to Fluoxetine's trend mentioned above; Amantadine's prescription rate has remained relatively stable over the last decade with minor fluctuations.

Conclusion

Both Rimantadine and Symmetrel (amantadine) have proven records of usage in patients with influenza virus infections, particularly Influenza A. They are supported by multiple clinical trials indicating their effectiveness over placebo treatments. Sometimes, these drugs might be used together under careful supervision by a healthcare professional as they can interact with each other. Due to their similar mechanisms of action - blocking the M2 protein ion channel and thus preventing viral replication - they are often prescribed under comparable circumstances.

Rimantadine is generally considered the first choice due to its more tolerable side effect profile compared to Symmetrel. It's also less likely than Symmetrel to cross the blood-brain barrier, which reduces central nervous system side effects like insomnia or mood changes.

In terms of accessibility, both medications are available in generic forms providing cost savings for patients paying out-of-pocket. Both may require an adjustment period meaning that full beneficial effects may not be noticeable right away.

The side effect profiles are somewhat similar between these two antivirals; however, Rimantadine is typically better-tolerated than Symmetrel which has a higher risk of causing neurological side effects such as confusion or hallucinations. It's crucial for patients taking either medication to monitor any adverse reactions closely and seek medical help immediately if severe symptoms occur.