Amantadine 100mg (Symmetrel)

What is Amantadine?

Amantadine is a prescription medication initially developed as an antiviral for influenza A, but later discovered to have neurological benefits, particularly in treating symptoms of Parkinson’s disease and drug-induced extrapyramidal reactions. It is available in capsule, tablet, and syrup forms — most commonly as 100mg oral capsules. Due to its unique dual activity, Amantadine plays a role in both infectious disease and neurology.

For influenza A, Amantadine was one of the first oral antivirals available. It works by interfering with viral replication, specifically targeting the M2 protein channel required for viral uncoating inside host cells. This stops the influenza virus from reproducing effectively. However, due to growing resistance, Amantadine is now rarely used for flu except in certain institutional outbreaks where resistance testing supports its use.

In neurology, Amantadine is frequently prescribed to manage symptoms of Parkinson’s disease, such as tremor, rigidity, and bradykinesia. It’s also beneficial in reducing levodopa-induced dyskinesia — a common complication in long-term Parkinson’s therapy. Additionally, it may be used off-label for fatigue in multiple sclerosis or to aid recovery in patients with traumatic brain injury.

Patients can buy Amantadine online through TrandFamilyStore-affiliated platforms that offer licensed telehealth consultations and secure pharmacy fulfillment. These services provide access to both branded and cheap generic versions, helping patients manage chronic neurologic or viral conditions without frequent in-person visits. Online ordering supports privacy, consistency, and proper follow-up with minimal disruption.

Amantadine is generally taken once or twice daily. It starts working within several days for motor symptoms and within 24–48 hours when used for viral flu. Tolerability is generally good, but side effects like insomnia or dry mouth may occur. Proper hydration, timing of doses, and physician supervision all help improve safety and outcomes.

How It Works

Amantadine operates through a unique pharmacological profile that influences both viral replication and neurological signaling. Its dual mechanism is what sets it apart from most other medications in its class.

As an antiviral, Amantadine blocks the M2 proton channel in the influenza A virus, an essential step in the virus’s ability to uncoat and replicate. By stopping the uncoating process, the virus is unable to release its RNA into host cells — a key requirement for spreading and multiplying. This antiviral effect is specific to influenza A and does not impact influenza B or other respiratory viruses. Due to resistance patterns, Amantadine’s antiviral role is now generally limited to institutional outbreaks or when other antivirals are contraindicated.

In the central nervous system, Amantadine acts as a weak, non-competitive NMDA receptor antagonist. These receptors are involved in glutamatergic transmission — a pathway implicated in excitotoxicity and motor dysfunction. By modulating NMDA activity, Amantadine helps reduce involuntary movements and cognitive slowing associated with Parkinson’s disease and drug-induced motor symptoms.

Amantadine also promotes dopamine release and inhibits dopamine reuptake in the brain, improving neurotransmitter availability. Dopamine is a critical messenger in motor control, and its deficiency is the hallmark of Parkinson’s disease. By supporting dopaminergic tone, Amantadine can alleviate tremor, bradykinesia, and rigidity — especially in early-stage or adjunctive treatment scenarios.

Its pharmacokinetics are linear, and the drug is primarily excreted unchanged by the kidneys. This makes renal function a crucial consideration in dosing. Patients with impaired renal clearance may experience drug accumulation, leading to confusion, hallucinations, or toxicity if not adjusted appropriately.

The effects of Amantadine are typically observed within a few days to weeks, depending on the indication. For Parkinsonian symptoms or EPS, benefits may be noticed within the first week. For influenza, prompt initiation (within 24 to 48 hours of symptom onset) is necessary for optimal antiviral effectiveness.

Because of its multitargeted effects, Amantadine is sometimes used off-label in brain injury rehabilitation, fatigue in multiple sclerosis, and even severe depression. However, these uses require careful medical oversight.

Dosage Information

The standard adult dose of Amantadine for Parkinson’s disease or drug-induced extrapyramidal symptoms is 100mg twice daily. In elderly patients or those with renal impairment, the dose may be reduced to 100mg once daily to minimize side effects. For influenza A, the typical dosage is also 100mg twice daily for 5 to 7 days, ideally started within 24 to 48 hours of symptom onset.

Amantadine should be taken with or without food, but consistency in timing helps maintain stable blood levels. To minimize insomnia, patients are often advised to take the second dose no later than early afternoon. For those with difficulty swallowing capsules, liquid formulations may be available through some pharmacies.

Dose adjustments are necessary in patients with kidney disease, as the drug is primarily excreted unchanged in the urine. Serum creatinine or estimated GFR should be evaluated prior to starting therapy in older adults or those with known renal impairment.

For patients switching from other Parkinson’s medications, titration should be done gradually. Combining Amantadine with other dopaminergic agents or anticholinergics should be coordinated carefully to avoid overlapping side effects like confusion, hallucinations, or dizziness.

Online providers working with TrandFamilyStore platforms typically assess medical history, current medications, and renal function as part of the prescribing process, ensuring a safe and tailored dosing approach.

Side Effects

Amantadine is generally well-tolerated, especially when started at lower doses. However, like all medications, it can cause side effects — some of which may require medical attention. The most commonly reported adverse effects include:

• Insomnia
• Dizziness or lightheadedness
• Dry mouth
• Nausea
• Peripheral edema (swelling in the legs or ankles)

In some patients, especially older adults or those with renal impairment, more significant side effects may appear, such as:

• Confusion or agitation
• Hallucinations or paranoia
• Blurred vision
• Livedo reticularis (mottled skin appearance, usually reversible)

Side effects like hallucinations are more likely when Amantadine is combined with other dopaminergic or anticholinergic medications. Dose reduction or temporary discontinuation often resolves symptoms. Patients should contact a healthcare provider immediately if they experience unusual thoughts, severe confusion, or balance problems.

Gradual dose reduction is recommended if stopping Amantadine, particularly after long-term use, to avoid withdrawal-like symptoms. Sudden cessation may exacerbate Parkinsonian symptoms or cause rebound dyskinesia in sensitive individuals.

Most side effects improve over time or with dose adjustment. To reduce risks, patients should stay hydrated, avoid alcohol during treatment, and monitor blood pressure if they are prone to orthostatic hypotension.

Warnings & Interactions

Amantadine should be used with caution in individuals with a history of seizures, heart failure, orthostatic hypotension, or renal impairment. The drug is excreted primarily by the kidneys, and accumulation may occur in patients with reduced renal clearance, increasing the risk of central nervous system side effects like confusion or hallucinations.

Amantadine may cause dizziness, blurred vision, or lightheadedness, particularly in the elderly. Activities requiring mental alertness, such as driving or operating machinery, should be avoided until the patient’s response to the drug is known.

Drug interactions may occur with other CNS-active medications, including anticholinergics, dopaminergic agents, and alcohol. Combining Amantadine with drugs that prolong the QT interval should be approached with caution, especially in those with underlying cardiac conditions.

Pregnant or breastfeeding women should avoid using Amantadine unless the potential benefits outweigh the risks. Animal studies have shown adverse fetal effects, and human data are limited.

Patients taking Amantadine should inform their healthcare provider about all prescription and non-prescription medications they use, including supplements and herbal products. Sudden discontinuation after prolonged use may lead to worsening of Parkinsonian symptoms or psychological withdrawal effects.

Online access to Amantadine through TrandFamilyStore includes prescriber review of health history and medication safety checks, ensuring that potential interactions and contraindications are properly managed before the drug is dispensed.