Drug Class: Dopaminergic Agent / NMDA Antagonist | Form: Oral Tablet | Prescription Status: Prescription Only (Rx) — DRAP Registered
What is Pk-Merz 100mg Tablet? Pk-Merz 100mg contains Amantadine Sulphate — a medicine with a unique dual mechanism that both increases dopamine activity in the brain and blocks NMDA glutamate receptors. This combination makes it effective for managing Parkinson's disease symptoms including tremor, rigidity, and slowness of movement. It is also used to treat movement disorders caused by antipsychotic medicines and has historically been used for Influenza A prevention and treatment. Pk-Merz is a long-term prescription medicine used under close neurological supervision.
What is Pk-Merz 100mg Used For?
- Parkinson's disease — tremor, rigidity, and slowness of movement (پارکنسن کی بیماری — کپکپاہٹ اور اکڑن)
- Drug-induced movement disorders — dyskinesia caused by antipsychotic medicines (دواؤں سے ہونے والی غیر ارادی حرکات)
- Levodopa-induced dyskinesia — involuntary movements in advanced Parkinson's patients
- Influenza A — antiviral prevention and early treatment (فلو کا علاج)
- Neurological rehabilitation following brain injury — under specialist supervision
How Does it Work? Amantadine works through two complementary pathways. First, it stimulates dopamine release and blocks dopamine reuptake in the brain — increasing dopamine availability to improve motor control in Parkinson's disease. Second, it blocks NMDA glutamate receptors — reducing excessive glutamate activity that contributes to involuntary movements and motor complications. Together these actions improve muscle control, reduce rigidity, and decrease dyskinesia.
Dosage and Administration
⚠️ Never stop suddenly — abrupt discontinuation can cause serious worsening of Parkinson's symptoms. Dose must be reduced gradually under doctor supervision. Take last dose of the day well before bedtime to avoid insomnia.
| Indication | Usual Adult Dose | Frequency | Notes |
|---|---|---|---|
| Parkinson's disease | 100mg | Once to twice daily | Dose adjusted by neurologist |
| Drug-induced dyskinesia | 100mg | Twice daily | As prescribed |
| Influenza A | 100mg | Twice daily | For 5 to 7 days only |
Active Ingredients
| Ingredient | Strength |
|---|---|
| Amantadine Sulphate | 100mg |
Who Should NOT Take Pk-Merz 100mg?
- Allergy to Amantadine or any component of the tablet
- Severe kidney disease — Amantadine is cleared through kidneys and accumulates dangerously
- History of epilepsy or seizures
- Severe heart failure or uncontrolled arrhythmia
- History of psychosis or severe psychiatric illness
- Pregnancy and breastfeeding
- Closed-angle glaucoma
- Children under 18 years unless specifically directed by specialist
Side Effects
Common: Insomnia (نیند نہ آنا), dizziness, difficulty concentrating, nausea, dry mouth, livedo reticularis — a purplish mottled skin discolouration on legs (ٹانگوں پر جالی نما نشانات — عام طور پر بے ضرر), mild ankle swelling.
Serious — Stop and seek emergency help immediately: Confusion or hallucinations — seeing or hearing things that are not real (وہم اور خیالی باتیں — فوری ڈاکٹر کو دکھائیں), severe agitation or aggressive behaviour, seizures or convulsions (مرگی کے دورے), significant worsening of heart failure with severe ankle swelling and breathlessness, Neuroleptic Malignant Syndrome if stopped abruptly — high fever with severe muscle rigidity, suicidal thoughts or severe mood changes.
Drug Interactions
| Medicine | Interaction |
|---|---|
| Anticholinergic medicines (e.g. Trihexyphenidyl) | Increased confusion, hallucinations, and anticholinergic side effects |
| Levodopa / Carbidopa | Additive dopaminergic effects — dose adjustment may be needed |
| CNS stimulants | Increased risk of agitation, insomnia, and irregular heartbeat |
| Diuretics (Triamterene / Hydrochlorothiazide) | Reduce Amantadine excretion — increases toxicity risk |
| Alcohol (شراب) | Increases CNS side effects including dizziness and confusion — avoid completely |
| Trimethoprim / Cotrimoxazole | Reduce kidney excretion of Amantadine — increased toxicity risk |
| QT-prolonging medicines | Increased risk of dangerous heart rhythm abnormalities |
Storage: Store below 25°C in a cool, dry place. Protect from moisture and direct sunlight. Keep out of reach of children (بچوں کی پہنچ سے دور رکھیں). Do not use after expiry date.
FAQs
Q: Can Pk-Merz be stopped suddenly if side effects develop? Never stop suddenly — abrupt discontinuation can cause dangerous worsening of Parkinson's symptoms and potentially life-threatening muscle rigidity. Always consult your neurologist for a gradual reduction plan.
Q: Why does Pk-Merz cause a purplish discolouration on the legs? This is called livedo reticularis — a common and generally harmless side effect of Amantadine caused by changes in small blood vessels under the skin. It usually disappears after stopping the medicine.
Q: Can Pk-Merz be taken at night for convenience? Avoid taking the last dose close to bedtime — Amantadine commonly causes insomnia. Take the final dose of the day at least 4 to 6 hours before sleeping.
⚕️ Medical Disclaimer: This information is for general awareness only and does not replace medical advice. Always consult a qualified doctor or pharmacist before taking any prescription medicine.