Indications
Amantadine Hydrochloride is used to treat Parkinson’s disease and similar movement problems (parkinsonism), including stiffness and tremor caused by some antipsychotic medicines. It also reduces involuntary movements (dyskinesia) caused by Levodopa. In the past it was used to prevent and treat influenza A, but most flu viruses are now resistant, so it is rarely used for flu today.
How It Works
Amantadine increases the release of dopamine, a brain chemical that is low in Parkinson’s disease, and blocks NMDA receptors that are involved in abnormal movements. This improves movement, stiffness and tremor. Against influenza A, it blocks a viral protein (M2) the virus needs to infect cells.
Dosage and Administration
Take as prescribed. For Parkinson’s disease adults usually start with 100 mg once daily, increasing after about a week to 100 mg twice daily; the doctor may adjust this. Take the last dose no later than mid-afternoon to avoid sleep problems. Older adults and people with kidney disease need lower doses. Do not stop suddenly, as symptoms can worsen sharply.
Interactions
Anticholinergic medicines (such as Trihexyphenidyl), antihistamines and some antidepressants can increase confusion and hallucinations. Medicines that affect the kidneys or urine, such as Hydrochlorothiazide and Triamterene, can raise Amantadine levels. Alcohol increases dizziness and confusion. Amantadine may reduce the effect of the live nasal flu vaccine.
Contraindications
Do not take if you are allergic to Amantadine, have severe kidney disease, have a history of seizures or stomach ulcers (unless a doctor advises), or have closed-angle glaucoma that is untreated.
Side Effects
- Dizziness, light-headedness on standing
- Nausea, dry mouth, constipation
- Difficulty sleeping, vivid dreams, nervousness
- Swelling of the ankles
- A blotchy purple net-like skin pattern on the legs (livedo reticularis)
- Confusion or hallucinations, especially in older people
Get urgent medical help if you have seizures, severe confusion or hallucinations, thoughts of harming yourself, blurred vision or eye pain, fainting, or high fever with stiff muscles (especially after stopping the medicine suddenly).
Pregnancy and Lactation
Avoid during pregnancy unless your doctor considers it essential, as it may harm the baby. Do not breastfeed while taking it; it passes into breast milk and may reduce milk supply.
Precautions and Warnings
Do not drive if you feel dizzy or have blurred vision. Use with care in heart failure, kidney disease, epilepsy, eye pressure problems and in people with mental health conditions. Some people develop strong urges such as gambling or overeating; tell your doctor if this happens.
Overdose
Overdose can cause agitation, confusion, hallucinations, heart rhythm problems, seizures and breathing problems. Seek emergency medical help immediately.
Therapeutic Class
Antiparkinson agent (dopaminergic, NMDA antagonist); antiviral (adamantane).
Storage
Store below 30°C in a dry place, away from light and out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.