Schedule H

Oral

• Tablets: 100 mg

• Capsules: 100 mg

• Syrup: 50 mg/5 mL

• Intravenous formulation: NOT AVAILABLE in India

INDICATIONS + DOSING — FOR CLINICIAN USE ONLY

Primary Indications (Approved / Standard in India)

1. Idiopathic Parkinson's Disease (monotherapy or adjunctive therapy)

Parameter Recommendation

Starting dose 100 mg once daily (morning)

Titration Increase to 100 mg twice daily after 1 week if tolerated

Usual maintenance dose 200 mg/day (given as 100 mg twice daily)

Maximum dose 400 mg/day (specialist supervision required)

Clinical Notes:

• Suitable for early-stage disease with mild motor symptoms

• May be added to levodopa therapy for managing wearing-off phenomenon

• Particularly useful for managing levodopa-induced dyskinesias

• Onset of benefit typically within 1–2 weeks

1. Drug-Induced Extrapyramidal Symptoms (including parkinsonism)

Parameter Recommendation

Starting dose 100 mg once daily

Titration May increase to 100 mg twice daily after 3–5 days based on response

Usual maintenance dose 100–200 mg/day (single or divided doses)

Maximum dose 300 mg/day

Clinical Notes:

• Continue treatment as long as causative agent is being administered

• Taper gradually over 1–2 weeks before discontinuation to avoid withdrawal symptoms

• Less efficacious for tardive dyskinesia; not considered first-line for this indication

• Anticholinergics may be preferred in acute dystonic reactions

1. Influenza A Virus Infection (treatment and prophylaxis)

Parameter Recommendation

Starting dose 100 mg twice daily

Titration Not applicable

Usual maintenance dose 200 mg/day in 2 divided doses

Maximum dose 200 mg/day

Duration 5–7 days for treatment; duration of exposure for prophylaxis

Clinical Notes:

• Treatment must be initiated within 48 hours of symptom onset for efficacy

• Widespread resistance among circulating Influenza A strains limits current utility

• Not recommended as first-line antiviral; oseltamivir preferred per ICMR/NCDC guidelines

• Historical use; retained for reference only

Secondary Indications – Adults (Off-label, if any)

1. Fatigue Associated with Multiple Sclerosis — OFF-LABEL

Parameter Detail

Indication Chronic fatigue in multiple sclerosis patients

Dose 100 mg once or twice daily

Duration Individualized; reassess benefit at 4–6 weeks

Specialist only Yes — Neurologist supervision required

Evidence basis Small RCTs; Indian neurology centre practice

Notes: Monitor renal function and CNS side effects. Discontinue if no improvement within 6 weeks.

1. Refractory Neuropathic Pain (diabetic neuropathy, post-herpetic neuralgia) — OFF-LABEL

Parameter Detail

Indication Adjunctive therapy for refractory neuropathic pain

Dose 100–200 mg/day in 1–2 divided doses

Duration Trial period of 2–4 weeks to assess response

Specialist only Yes — Pain medicine or Neurology supervision

Evidence basis Limited evidence; used in tertiary neuroscience centres in India

Notes: Reserved for cases unresponsive to first-line agents (gabapentinoids, tricyclics). Start at lowest dose.

PAEDIATRIC DOSING (Specialist Only)

Primary Indications (Standard in India)

1. Influenza A Virus Infection (historical use)

1–9 years 5 mg/kg/day in 2 divided doses 150 mg/day 5 days

≥10 years 100 mg twice daily 200 mg/day 5 days

Clinical Notes:

• Must initiate within 48 hours of symptom onset

• CNS excitation (irritability, insomnia) more common in younger children

• Not first-line therapy; oseltamivir preferred per current NCDC guidance

• Contraindicated in infants <1 year

1. Drug-Induced Extrapyramidal Reactions (children >5 years)

Parameter Recommendation

Starting dose 1.5 mg/kg/day in 2 divided doses

Titration May increase to 3 mg/kg/day based on response

Usual maintenance dose 2–3 mg/kg/day in 2 divided doses

Maximum dose 200 mg/day (100 mg twice daily)

Clinical Notes:

• Monitor for neurobehavioural changes (agitation, sleep disturbance)

• Taper gradually before discontinuation

• Paediatric neurologist or psychiatrist supervision recommended

Secondary Indications – Paediatric (Off-label, if any)

Paediatric-Onset Parkinsonism (genetic or secondary causes) — OFF-LABEL

Parameter Detail

Indication Rare genetic or secondary parkinsonism in children

Dose 1–3 mg/kg/day in 2 divided doses

Duration Long-term; individualized

Specialist only Yes — Paediatric Neurologist supervision mandatory

Evidence basis Extrapolated from adult data; paediatric neurology protocols

Notes: Start at lowest dose; titrate slowly over weeks with close neurological follow-up.

Age Restrictions:

• Not recommended in children <1 year of age except under direct paediatric neurology supervision with documented indication.

Amantadine undergoes predominant renal excretion; dose reduction is essential in renal impairment.

60 No adjustment required

30–59 100 mg once daily

15–29 100 mg every 48 hours

<15 (not on dialysis) 100 mg every 7 days or avoid

Haemodialysis 100 mg after each dialysis session (poorly dialyzable)

Notes:

• Monitor closely for signs of CNS toxicity (confusion, hallucinations, myoclonus)

• Accumulation risk is high; serum levels not routinely available in India

• Known hypersensitivity to amantadine or any excipient

• Untreated narrow-angle (angle-closure) glaucoma

• Severe renal impairment (CrCl <15 mL/min) without dialysis access

• Concurrent use of live attenuated influenza vaccine (within 2 weeks)

• Breastfeeding (absolute contraindication)

• Elderly patients (increased risk of CNS toxicity, falls, and urinary retention)

• Pre-existing psychiatric disorders (may precipitate or worsen psychosis, hallucinations)

• History of seizures or epilepsy (lowers seizure threshold)

• Congestive heart failure or peripheral oedema (may exacerbate fluid retention)

• Concomitant use of other anticholinergic or dopaminergic agents

• Patients operating machinery or driving (CNS impairment possible)

• Abrupt discontinuation — risk of withdrawal syndrome resembling neuroleptic malignant syndrome

Parameter Recommendation

Risk category Avoid unless clearly necessary; potential teratogenicity

Trimester-specific risk First trimester exposure associated with cardiac malformations in animal studies; limited human data

Preferred alternatives Levodopa-based therapy (with specialist input) for parkinsonian indications

When may be used Only if maternal benefit clearly outweighs fetal risk; specialist decision

Monitoring Fetal echocardiography if exposure occurs; monitor for congenital anomalies

Parameter Recommendation

Compatibility Contraindicated during breastfeeding

Drug levels in milk High; excreted significantly into breast milk

Infant risk Irritability, poor feeding, sleep disturbances, potential CNS toxicity

Preferred alternatives Levodopa-based regimens under neurologist guidance

Recommendation Discontinue breastfeeding or switch to alternative therapy

Parameter Recommendation

Starting dose 100 mg once daily

Titration Slow; increase only after 2 weeks if tolerated

Maximum dose 200 mg/day unless under close specialist monitoring

Additional risks Confusion, visual hallucinations, orthostatic hypotension, urinary retention, falls

Monitoring Renal function, cognitive status, gait stability, and hydration

Notes: Elderly patients are particularly vulnerable to anticholinergic and dopaminergic adverse effects. Preferentially use lowest effective dose.

Interacting Drug Effect Recommendation

Levodopa Potentiation of dopaminergic effects; increased dyskinesias Reduce levodopa dose if dyskinesias emerge

Anticholinergics (trihexyphenidyl, benztropine) Additive anticholinergic toxicity (confusion, hallucinations, urinary retention) Avoid combination or use with extreme caution

CNS stimulants (amphetamines, methylphenidate) Increased risk of agitation, insomnia, seizures Avoid concurrent use

Quinidine / Quinine Reduced renal clearance of amantadine; increased plasma levels Monitor for toxicity; consider dose reduction

Live attenuated influenza vaccine May reduce vaccine efficacy Avoid amantadine from 48 hours before to 14 days after vaccination

Interacting Drug Effect Recommendation

Thiazide diuretics Reduced amantadine clearance; increased CNS toxicity risk Monitor for toxicity

Memantine Additive NMDA antagonism; risk of confusion and psychosis Avoid combination if possible

Trimethoprim Competes for renal tubular secretion; may increase amantadine levels Monitor closely

Alcohol Enhanced CNS depression Advise patients to limit or avoid alcohol

Bupropion Additive seizure risk Use cautiously; monitor

• Nausea, loss of appetite

• Dizziness, lightheadedness

• Dry mouth

• Insomnia, vivid dreams

• Peripheral oedema (ankle swelling)

• Livedo reticularis (mottled, purplish skin discolouration — typically benign and reversible)

• Constipation

Adverse Effect Notes

Acute confusional state / toxic delirium More common in elderly and renal impairment; requires immediate discontinuation

Psychosis / visual hallucinations May occur at therapeutic doses; stop drug and assess

Suicidal ideation Rare; monitor mood, especially early in treatment

Seizures Increased risk in seizure-prone individuals or at high doses

Neuroleptic Malignant Syndrome-like reaction May occur on abrupt withdrawal; always taper gradually

Corneal oedema / visual disturbance Rare; refer to ophthalmology if visual symptoms develop

Long-term (chronic use) Renal function (every 6–12 months); psychiatric assessment; peripheral oedema; skin examination for livedo reticularis

Special situations If used for influenza — confirm initiation within 48 hours of symptom onset

• Amantrel® (Cipla)

• Parkitidin® (Abbott)

• Symadine® (Intas)

• Adamet® (Sun Pharma)

• Mentadine® (Psychotropics India Ltd)

• Amanta® (Alkem)

Note: Amantadine is NOT included in NLEM; prices vary across brands and regions. Government supply availability is limited.

1. Early Parkinson's disease: Amantadine provides modest symptomatic benefit and may be used as initial monotherapy for mild symptoms or gait instability before initiating levodopa.

1. Levodopa-induced dyskinesias: One of the few agents with evidence for reducing dyskinesias when added to established levodopa therapy.

1. Livedo reticularis: This characteristic mottled skin rash is benign, dose-related, and reversible upon discontinuation; does not necessitate stopping treatment unless cosmetically troublesome to the patient.

1. Renal impairment: Aggressive dose reduction is mandatory; CNS toxicity (confusion, hallucinations, myoclonus) is a predictable consequence of accumulation.

1. Never stop abruptly: Gradual tapering over 1–2 weeks is essential to prevent withdrawal reactions mimicking neuroleptic malignant syndrome (hyperthermia, rigidity, autonomic instability).

1. Influenza use is obsolete: Due to widespread resistance among Influenza A strains, amantadine should no longer be used for influenza treatment or prophylaxis; oseltamivir is preferred.

amantadine; parkinsonism; antiparkinsonian; antiviral; dopaminergic; NMDA-antagonist; EPS-management; renal-dose-adjustment; elderly-caution; neuropsychiatric; livedo-reticularis

RxIndia v1.0 — 10 Jan 2025

• CDSCO approved product information

• Indian Pharmacopoeia / National Formulary of India

• API Textbook of Medicine

• AIIMS Neurology treatment protocols

• NCDC Influenza treatment guidelines

• WHO Essential Medicines List (paediatric influenza — historical reference)

• Goodman & Gilman's The Pharmacological Basis of Therapeutics (supportive pharmacology)

• Indian specialist practice (Neurology, Psychiatry)