What Is Amantadine?
Amantadine is a type of medication that is used to treat some symptoms of Parkinson’s disease (PD), including tremors and dyskinesias. Dyskinesias are the uncontrollable, abnormal movements that are a common side effect of long-term levodopa therapy. Carbidopa-levodopa therapy is the most effective medication available to treat the motor symptoms of PD, but some people are also prescribed additional medications to manage their symptoms, like amantadine.1-3
Amantadine may also reduce the fluctuations in motor symptoms experienced by many people with PD. People treated with carbidopa-levodopa often experience fluctuating symptoms of PD and are described as having “on” and “off” episodes. “On” episodes are experienced when medication is working and symptoms are minimal, and “off” episodes are when the medication hasn’t yet taken effect or is wearing off and symptoms become more apparent. “Off” episodes can interfere with daily activities and may be experienced multiple times a day. They may last a few minutes or as long as a few hours.1-3
How amantadine works
Amantadine is a weak, uncompetitive antagonist of the NMDA receptor. While the exact way Amantadine works isn’t fully understood, scientists believe that they may increase dopamine release and block dopamine reuptake in the brain. Amantadine has been tested in clinical trials and has demonstrated effectiveness in reducing dyskinesia.1,2,4
Formulations of amantadine
There are several different formulations of amantadine, including:
- Symmetrel® (amantadine)
- Gocovri® (amantadine ER)
- Osmolex™ (amantadine ER)
Symmetrel is used in people with PD to help with tremor. In clinical trials, Symmetrel demonstrated effectiveness as a monotherapy (used by itself) and in combination with other therapies for PD. Symmetrel may also be used to reduce the severity and duration of dyskinesia.1,5
Gocovri is approved for the treatment of dyskinesia in people with PD who are receiving levodopa therapy with or without additional dopaminergic medications. In addition to reducing dyskinesia, Gocovri is approved as a supplemental treatment to levodopa/carbidopa in people with Parkinson's experiencing off episodes. Gocovri is an extended-release capsule containing amantadine that is taken orally once daily at bedtime. The capsule slowly releases the medication into the body, providing a consistent level of medication in the morning and throughout the day, reducing dyskinesia and reducing the “off-time” experienced by people with PD taking levodopa therapy.2,6
Osmolex is an extended-release formula that is approved for the treatment of PD and extrapyramidal symptoms from other medications.7,8 Extrapyramidal symptoms are physical side effects caused by some medications, including dystonia (muscle spasms that cause twisting movements), dyskinesia, akinesia (the loss of the ability to move muscles), and akathisia (a restlessness that causes people to move).9,10 Osmolex is taken once daily in the morning and the medication is slowly released into the body throughout the day. Extended-release formulas like Osmolex may provide more consistent medication and reduce fluctuations in symptoms.7,8
Side effects of amantadine
Each medication has its own set of possible side effects.
Common side effects of Symmetrel include dizziness, weakness, dry mouth, constipation, blurry vision, skin blotches, impaired mental acuity, or orthostatic hypotension (falling blood pressure upon standing). Some side effects are serious and require immediate medical care, including mood or mental changes, swelling of extremities, difficulty urinating, and shortness of breath.1
The most commonly experienced side effects by patients taking Gocovri in clinical trials were hallucination (seeing or hearing things that aren’t there), dizziness, dry mouth, swelling of the legs or feet (peripheral edema), constipation, falling, and orthostatic hypotension, the sudden lowering of blood pressure upon standing.2
Osmolex may cause side effects such as nausea, dizziness or lightheadedness, and difficulty sleeping (insomnia). Osmolex may increase the risk of falling asleep during normal activities and may increase symptoms of depression or suicidal behavior.8
Note that this list of side effects is not a complete list, and people with PD should talk with their doctor to learn more about the side effects of each medication.
It is important that people with PD see a movement disorder specialist, who is specifically trained in treating PD and understands the role of medications, including which drugs may worsen symptoms. It is also important to talk with your healthcare provider before starting or stopping any new treatments, including over-the-counter medications and alternative treatments.