PK-MERZ

PK-Merz 100 mg film-coated tablets contain amantadine sulfate, an antiparkinsonian medicine. It is used in adults for selected symptoms of Parkinson’s disease and certain medicine-induced movement disorders.

The dose must be individually prescribed according to symptoms, age, kidney function, cardiac status, additional medicines and the patient's response to treatment.

PK-Merz 100 mg – approved uses, administration and precautions

What is PK-Merz used for?

• rigidity associated with Parkinson’s disease;
• tremor;
• reduced ability to move – hypokinesia;
• difficulty initiating or performing movement – akinesia;
• parkinsonian movement disorders caused by neuroleptics or medicines with a similar mechanism;
• extrapyramidal symptoms such as early dyskinesia, akathisia and drug-induced parkinsonism.

PK-Merz helps control selected symptoms but does not eliminate the underlying cause of Parkinson’s disease.

How is PK-Merz taken?

Swallow the tablets with a small amount of liquid, preferably in the morning and afternoon. The final daily dose should not be taken after 4 p.m.

The tablet is not intended to be divided. Its score does not provide two equal doses.

Kidney function and dose adjustment

Amantadine is primarily eliminated through the kidneys. It may accumulate and cause toxicity in patients with impaired kidney function.

The prescriber therefore adjusts both the dose and the interval between doses according to glomerular filtration rate or creatinine clearance. Patients must not calculate or change the renal dose themselves.

ECG monitoring

An ECG may be performed before treatment, after the first and third weeks, before each further dose increase and approximately two weeks after an increase.

Stop treatment and contact a doctor urgently if palpitations, sudden dizziness, fainting or an irregular heartbeat develops.

When must PK-Merz not be used?

• allergy to amantadine or an excipient;
• severe decompensated heart failure;
• cardiomyopathy or myocarditis;
• second- or third-degree AV block;
• heart rate below 55 beats per minute;
• known QT prolongation, prominent U waves or familial congenital long-QT syndrome;
• previous serious ventricular arrhythmia, including torsades de pointes;
• low blood potassium or magnesium;
• combined use with budipine or another QT-prolonging medicine.

When is particular caution required?

Tell the doctor about prostate enlargement, difficulty urinating, angle-closure glaucoma, kidney impairment, seizures, agitation, confusion, delirium, serious psychiatric illness, cardiovascular disease, a pacemaker or treatment with memantine.

Suicidal thoughts and behaviour have been reported during amantadine treatment. Thoughts of self-harm require immediate medical attention.

Impulse-control disorders

Patients may rarely develop an uncontrollable urge to gamble, overspend, shop excessively, overeat or engage in unusually intense sexual behaviour. A family member or caregiver should inform the doctor if such changes occur.

Interactions

PK-Merz must not be combined with selected medicines that prolong the QT interval. These may include certain antiarrhythmics, antipsychotics, antidepressants, antihistamines, antibiotics and antifungal medicines.

Other relevant interactions include:

• anticholinergic medicines, which may increase confusion and hallucinations;
• levodopa and other antiparkinsonian medicines;
• memantine, which may increase both effects and adverse reactions;
• triamterene combined with hydrochlorothiazide, which may reduce amantadine elimination;
• other products containing amantadine.

Avoid alcohol because tolerance to alcohol may be reduced and neurological adverse effects may become stronger.

Pregnancy and breastfeeding

Use during pregnancy is reserved for situations in which the doctor considers treatment absolutely necessary. Amantadine passes into breast milk, so a medical decision is required regarding treatment and breastfeeding.

Driving and operating machinery

PK-Merz may affect attention, alertness, vision and reaction time. Do not drive or operate machinery unless the doctor has confirmed that it is safe.

Possible side effects

• sleep disturbance, agitation and restlessness;
• urinary retention, particularly in prostate enlargement;
• confusion, psychotic symptoms or visual hallucinations;
• livedo reticularis, sometimes with swelling of the lower legs and ankles;
• nausea, dizziness and dry mouth;
• a fall in blood pressure when standing;
• blurred vision or damage and swelling of the cornea;
• abnormal heart rhythm;
• seizures, muscle cramps or altered sensation in the limbs.

Composition and pack

• Active ingredient: 100 mg of amantadine sulfate per film-coated tablet.
• Appearance: round, biconvex, orange tablet with a score on one side.
• Division: the tablet is not intended to be divided.
• Pack size: 30 tablets in three blisters of ten.
• Relevant excipients: lactose monohydrate and Yellow Orange E110.
• Marketing authorisation holder: Salveo d.o.o. Beograd, Serbia.
• Manufacturer: Merz Pharma GmbH & Co. KGaA, Germany.
• ATC code: N04BB01.
• EAN: 4046222740153.
• Supply status: prescription only.

Storage

Keep out of the sight and reach of children and store below 25°C. Do not use after the expiry date stated on the carton and blister.

Related article

Read: Is Parkinson’s disease hereditary and curable?

Important: dietary supplements are not substitutes for PK-Merz and must not be added automatically to antiparkinsonian treatment.

Source: Current PK-Merz 100 mg patient leaflet approved by the Serbian Medicines and Medical Devices Agency – ALIMS. View the official patient leaflet.
Leaflet last approved: January 2026. Source checked: 2 August 2026.

This information does not replace neurological assessment, an individual treatment plan, ECG and laboratory monitoring or the original patient leaflet.