Symmetrel (Amantadine) – Patient Information (Australia)

Symmetrel is the brand name for amantadine, a medicine used in specific neurological and movement-related conditions. It may also be used for certain viral prevention purposes, depending on local guidance and individual suitability. This page is designed to help you understand how Symmetrel works, how it’s taken, what to watch for, and practical tips for safe use in Australia.

Basic product information

Note: Product strengths and formulations can vary by supplier and jurisdiction. If you’re unsure which strength you have, check the package label or ask your pharmacist.

How Symmetrel works (mechanism of action)

Amantadine affects the brain and nervous system in several ways. The exact mechanism depends on the condition being treated, but includes:

• Modulating dopamine activity: Amantadine can increase dopaminergic activity and help improve movement in certain Parkinsonian syndromes.
• NMDA receptor effects: It may act as an NMDA receptor antagonist (glutamate-related pathway), which can influence symptoms such as rigidity and slowness.
• Antiviral activity (influenza A): For influenza A prevention, amantadine interferes with viral processes required for replication. This is specific to influenza A and is not useful for influenza B.

Because Symmetrel targets brain signalling pathways, effects for movement conditions can take days to weeks to become clearly noticeable, while antiviral prevention benefits, if used, depend on timing relative to exposure.

Pharmacokinetics (how the body handles it)

Understanding pharmacokinetics helps explain why dosing schedules matter and why kidney function can be important.

• Absorption: Amantadine is absorbed after oral dosing, with variable absorption among individuals.
• Distribution: It distributes into body tissues, including the central nervous system.
• Metabolism: Amantadine is not extensively metabolised by the liver.
• Elimination: The kidneys excrete most of the drug unchanged. This is a key reason dose adjustments may be needed in renal impairment.
• Half-life: The elimination half-life is influenced by kidney function. In people with reduced kidney function, the medicine can build up, increasing the risk of side effects.

Practical implication: If you have kidney disease, your prescriber may adjust the dose and/or dosing interval to reduce accumulation and side effects.

Typical uses in Australia

Symmetrel (amantadine) may be used for:

• Parkinson’s disease and Parkinsonian syndromes (including symptom relief for tremor, stiffness, and slowness in selected patients).
• Drug-induced extrapyramidal symptoms (in some situations).
• Multiple sclerosis-related fatigue (in some cases, depending on clinical assessment and local practice).
• Prevention of influenza A in particular circumstances where appropriate guidance supports use.

Important: The role of amantadine for influenza prevention may be limited by current influenza treatment and resistance patterns. Your pharmacist or clinician can explain whether it is relevant to your current season and risk profile.

Timing: when and how to take Symmetrel

For best tolerability:

• Follow your dosing schedule exactly as written on your medication label.
• Consistency helps: Take it at the same times each day.
• Morning preference: Many people are advised to take doses earlier in the day to reduce the chance of insomnia or agitation.
• If you miss a dose: Take it when you remember unless it is close to your next dose. Don’t take a double dose to make up for missed tablets.

If you’re taking multiple medicines, ask your pharmacist to check the timing so that interactions are minimised.

Food interactions

Amantadine can generally be taken with or without food, but eating may influence how quickly it’s absorbed in some people.

• Take with food if it upsets your stomach.
• Stay consistent: If you typically take it with meals, continue that pattern to avoid changes in how you feel.
• Avoid sudden dietary changes that significantly alter urine pH unless your clinician advises it.

Urine pH note: Because amantadine is excreted by the kidneys, medicines and conditions that affect urine acidity can change how long it stays in your body. Do not make major changes to supplements or diets aimed at altering urine pH without discussing with a healthcare professional.

Alcohol and medicine interactions

Alcohol

Alcohol may worsen side effects such as dizziness, sleepiness, blurred vision, and impaired coordination. In people who already experience these effects from Symmetrel, alcohol can increase fall risk and affect safety at work or while driving.

• General advice: Limit alcohol or avoid it if you notice dizziness or mood changes.
• Be cautious: Avoid drinking if you are adjusting to a new dose.

Medicine interactions (common examples to discuss with your pharmacist)

Because amantadine affects the brain and is cleared through the kidneys, interactions may occur through additive effects or altered clearance.

• Other medicines that affect the central nervous system: sedatives, sleep medicines, some antidepressants, and antipsychotics may increase dizziness, confusion, or unusual behaviour.
• Other Parkinson’s medicines: combining therapies may change benefit or side effects; monitoring is important.
• Medicines affecting urine pH: some agents can alter kidney excretion. Tell your pharmacist if you take bicarbonate, certain diuretics, or other drugs aimed at changing urine characteristics.
• Kidney-affecting medicines: any medication that stresses kidney function may change amantadine levels.
• Vaccines/antivirals (for influenza): relevant choices depend on timing and current influenza guidance.

Always check your full list of medicines and supplements (including over-the-counter products). Your pharmacist can screen for potential interactions.

Indications: what Symmetrel is prescribed for

In clinical practice, indications commonly include:

• Parkinson’s disease: to reduce motor symptoms such as rigidity and bradykinesia in selected patients.
• Parkinsonian syndromes: including drug-induced or atypical forms where appropriate.
• Other neurological uses: such as symptoms related to fatigue in some circumstances, guided by clinician assessment.
• Influenza A prevention: only in circumstances where it aligns with current recommendations and resistance patterns.

Because the “best” option depends on your diagnosis, symptom profile, age, kidney function, and other medicines, your pharmacist may explain how amantadine compares with alternatives for your particular situation.

Dosing: typical adult regimens (guidance)

Dosing must be individualised. The following is general information to help you understand common dosing patterns; always follow the dose on your label.

• Parkinson’s disease / Parkinsonian symptoms: dosing is often divided across the day (commonly once or twice daily in many regimens), with adjustments based on response and tolerability.
• Renal impairment: dose reductions or longer intervals may be needed because amantadine is cleared by the kidneys.
• Older adults: older people may be more sensitive to dizziness, confusion, hallucinations, and falls; lower starting doses may be used.

Starting and adjusting doses: Clinicians may begin with a lower dose and increase slowly to reduce side effects. The “right” dose for you depends on symptom improvement and tolerability.

If you have kidney disease, be especially careful: do not change your dose without professional advice.

Safety profile: common side effects and what to do

Common side effects

Many people tolerate Symmetrel reasonably well, but side effects can occur, including:

• Dizziness or light-headedness
• Nausea or loss of appetite
• Insomnia or sleep disturbance
• Anxiety or restlessness
• Dry mouth
• Headache
• Swelling (oedema) in some cases

Practical tips: If dizziness occurs, rise slowly from sitting or lying. If insomnia occurs, take doses earlier in the day (ask your pharmacist before changing schedule).

Serious side effects (seek urgent medical help)

Contact a doctor urgently or seek emergency care if you experience:

• Severe confusion, extreme agitation, or hallucinations
• New or worsening abnormal movements (involuntary muscle movements)
• Chest pain, fainting, or severe palpitations
• Allergic reaction symptoms: facial swelling, rash, trouble breathing
• Seizures

Why this matters: Amantadine can affect brain function, and risk of neuropsychiatric effects may increase in older adults or with impaired kidney function.

Who needs extra caution

• People with kidney impairment (higher risk of drug accumulation)
• Older adults (higher risk of confusion, falls, and insomnia)
• Those with a history of psychiatric illness (monitor closely)
• People taking interacting medicines that affect the nervous system

Practical use tips for everyday life

• Keep track of symptom response: note changes in walking, tremor, stiffness, mood, or sleep for the first few weeks.
• Monitor dizziness: avoid driving or operating machinery if you feel unsteady, especially when starting or changing dose.
• Hydration helps: staying well-hydrated may support kidney function and reduce dizziness in some people (follow your clinician’s advice if you have fluid restrictions).
• Prevent falls: use good lighting, remove trip hazards, and stand up slowly.
• Set reminders: use phone alarms or a pill organiser to avoid missed doses.
• Do not stop suddenly without advice: if you need to discontinue, your pharmacist or clinician can guide tapering (if applicable) or alternative plans.

Alternative options

Depending on your condition and symptom pattern, other medicines may be considered. Alternatives vary by diagnosis and clinical history.

For Parkinson’s disease

• Levodopa-based therapies (often central to treatment)
• Dopamine agonists
• MAO-B inhibitors
• Anticholinergic medicines (selected patients)

For influenza A prevention (seasonal considerations)

• Current influenza antivirals and prevention strategies, guided by seasonal recommendations
• Vaccination (often the preferred prevention measure)
• Non-pharmacological measures such as hygiene and exposure precautions during outbreaks

Your pharmacist can help you understand which option is most suitable and how it compares in terms of effectiveness, side effects, and interactions.

Market and legal context for Australia

In Australia, medicines are regulated under the Therapeutic Goods Administration (TGA) framework. Products containing amantadine are subject to relevant scheduling rules and pharmacy supply requirements. Availability and supply pathways can vary between brand and formulation.

• Regulatory oversight: TGA evaluates medicines for quality, safety, and efficacy.
• Pharmacy supply: In practice, supply is guided by scheduling status, clinical appropriateness, and professional requirements.
• Clinical guidance: Treatment choices may be influenced by updates from Australian clinical bodies and infectious disease guidance during influenza seasons.

Vaccines and infection control recommendations are updated frequently, particularly for influenza. Your pharmacist can help you locate the most relevant advice for current local conditions.

Recent guidance and information updates (how to stay current)

Recommendations for influenza prevention and antiviral use can change due to:

• Virus resistance patterns
• Availability of more effective antivirals
• Seasonal severity and exposure risks

For movement disorders, neurologists and general practitioners may update preferred treatment pathways based on evidence and individual patient factors. If you’re using Symmetrel for influenza prevention or another condition, it’s a good idea to confirm current guidance with a healthcare professional at the start of each relevant season.

Delivery and availability (online pharmacy)

Availability can vary by stock levels and tablet/capsule strength. If you order online:

• Processing time: Most orders are processed within standard business hours (depending on supplier and stock).
• Delivery: Delivery timeframes depend on your location and courier service. We recommend placing orders early where possible.
• Packaging: Medicines are typically supplied in manufacturer packaging with clear labelling and consumer medicines information.

If Symmetrel is temporarily unavailable, your pharmacist may suggest suitable alternatives or discuss options to help maintain continuity of care.

FAQ

1) Is Symmetrel used for Parkinson’s disease?

Yes. Amantadine is used in selected patients with Parkinson’s disease and related conditions to help reduce certain symptoms. Whether it is appropriate for you depends on your diagnosis, symptom pattern, age, and kidney function.

2) How soon will I feel an effect?

Some people notice changes within days, while others may take longer. For movement symptoms, improvements can build over time as your dose is adjusted and your body adapts.

3) Can I take Symmetrel with food?

Generally, yes. If it upsets your stomach, taking it with food may help. Try to take it consistently at similar times each day.

4) What should I do if I miss a dose?

Take it when you remember unless it’s close to your next dose. Do not take two doses at once. If you miss several doses, contact your pharmacist for advice on how to restart.

5) Does Symmetrel cause insomnia?

It can. Many people are advised to take it earlier in the day. If sleep problems occur, speak with your pharmacist before changing the schedule.

6) Can I drink alcohol while taking Symmetrel?

It’s best to limit or avoid alcohol, particularly if you experience dizziness, drowsiness, or mood changes. Alcohol can increase fall and accident risk.

7) What interactions are the most important to check?

Please discuss your full medicine list, especially drugs that affect the brain, medicines that can impact kidney function, and medicines that may alter urine pH. Your pharmacist can screen interactions.

8) Is amantadine safe in kidney disease?

Extra caution is needed. Because it is largely cleared by the kidneys, your dose may need adjustment to avoid accumulation and side effects. Never adjust dose without professional guidance.

9) Can Symmetrel help prevent flu?

In some circumstances, amantadine has been used to prevent influenza A. However, current influenza recommendations may favour other prevention and treatment strategies, and resistance patterns may limit effectiveness. Confirm the most up-to-date advice with a healthcare professional.

10) What are the warning signs that mean I should stop and get help?

Seek urgent medical help for severe confusion, hallucinations, fainting, seizures, allergic reaction symptoms, or serious heart-related symptoms such as severe palpitations or chest pain.

Disclaimer: This information is general and designed to support safe use. Always follow the instructions provided with your medicine and consult a healthcare professional for personalised advice, particularly if you have kidney problems, a history of mental health conditions, or you are taking other medicines.