Amantadine: Price, Dosage & Where to Buy

Amantadine is a medicine used for Parkinson's disease, particularly to treat dyskinesia, the involuntary movements associated with levodopa-based treatment; its pharmacological class is not formally specified in the label. It requires a prescription in the United Kingdom, and the extended-release product GOCOVRI is also indicated as an additional treatment for periods when levodopa/carbidopa treatment is less effective.

The GOCOVRI extended-release formulation of amantadine is indicated for dyskinesia in people with Parkinson's disease who receive levodopa-based treatment. Dyskinesia means involuntary movements that can occur during treatment. This indication includes people receiving levodopa with or without other dopaminergic medicines.

GOCOVRI is also indicated as an additional treatment alongside levodopa/carbidopa for people experiencing "off" episodes, when the benefit of their Parkinson's treatment wears off and symptoms return. These indications relate specifically to GOCOVRI; its label states that it is not interchangeable with other immediate-release or extended-release amantadine products.

Amantadine acts on chemical signalling in the brain involved in movement control. Its effects include reducing activity at NMDA receptors, which respond to the chemical messenger glutamate, and influencing dopamine signalling. Dopamine helps coordinate movement, while excessive glutamate activity can contribute to abnormal movement patterns.

These actions help explain its use for involuntary movements associated with levodopa treatment in Parkinson's disease. The precise way its different actions contribute to clinical benefit is not fully understood.

The label lists oral capsules and tablets at 100 mg, coated-pellet capsules at 68.5 mg and 137 mg, and oral solutions at 50 mg/5 mL and 100 mg/10 mL. The dosing schedule described here relates specifically to GOCOVRI extended-release capsules, not to all amantadine products. The usual starting dose is 137 mg orally once daily at bedtime.

The label lists an increase after one week to 274 mg once daily at bedtime. The label lists a starting dosage of 68.5 mg once daily at bedtime for moderate renal impairment, with a maximum recommended dosage of 137 mg once daily at bedtime. The label lists 68.5 mg once daily at bedtime as the initial and maximum dosage for severe renal impairment.

GOCOVRI is contraindicated in end-stage renal disease and is not substitutable with other amantadine immediate-release or extended-release products. The label describes administration with or without food and advises against sudden discontinuation; withdrawal requires a planned reduction where possible.

For GOCOVRI, the label states that a missed dose is followed by the next dose at its scheduled time. A missed dose should not be compensated for with a double dose. Other amantadine formulations may have different schedules, so a pharmacist can clarify the advice for the particular product.

There are no adequate data on developmental risk from amantadine use in pregnant women. Animal studies suggest potential harm to the unborn baby, including developmental abnormalities and reduced fetal weight. Amantadine passes into human milk, but the amounts have not been quantified and the risk to a breastfed infant is unknown.

It may alter milk production or excretion, although its effect on milk supply has not been evaluated in breastfeeding mothers. Pregnancy and breastfeeding decisions should be discussed with the prescriber.

The GOCOVRI label specifies storage at 20°C to 25°C, with excursions permitted to 15°C to 30°C. Follow the storage directions on the particular product's label to maintain quality.