Amantadine for treating Parkinson's disease

FDA Approves Osmolex ER (amantadine) for the treatment of Parkinson’s disease and drug-Induced extrapyramidal reactions. Amantadine is an antiviral medicine that blocks the actions of viruses in the body. It is used to treat or prevent influenza A in adults and children. It may not be effective during every flu season because certain strains of the virus may be resistant to this medicine. It should not be used in place of getting a yearly flu shot.

Amantadine is also used to treat "Parkinson-like" symptoms such as stiffness or tremors, shaking, and repetitive uncontrolled muscle movements that may be caused by the use of certain drugs.

Amantadine side effects
Get emergency medical help if you have signs of an allergic reaction: hives ; difficult breathing; swelling of your face, lips, tongue, or throat. Call your doctor at once if you have: extreme drowsiness, falling asleep suddenly even after feeling alert; a light-headed feeling, like you might pass out; shortness of breath (even with mild exertion), swelling in your hands or feet;
painful or difficult urination; depression, agitation, aggression, behavior changes, hallucinations, thoughts of hurting yourself; a seizure; or severe nervous system reaction-very stiff (rigid) muscles, high fever, sweating, confusion, fast or uneven heartbeats and tremors.
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Links between hallucinations and dopamine

Researchers at Columbia University Irving Medical Center (CUIMC) and New York State Psychiatric Institute (NYSPI) found that people with schizophrenia who experience auditory hallucinations tend to hear what they expect, an exaggerated version of a perceptual distortion that is common among other people without hallucinations.

Those with hallucinations and other psychotic symptoms are known to have elevated dopamine, the main area of focus for available treatments for psychosis, but it was unclear how this could lead to hallucinations.

The researchers found that elevated dopamine could make some patients rely more on expectations, which could then result in hallucinations. Human brain uses prior experiences to generate sensory expectations that fill in the gaps when sounds or images are distorted or unclear.

In individuals with schizophrenia, this process appears to be altered, leading to extreme perceptual distortions, such as hearing voices that are not existing. Furthermore, while such hallucinations are often successfully treated by antipsychotic drugs that block the neurotransmitter dopamine in a brain structure known as the striatum, the reason for this has been a mystery since this neurotransmitter and brain region are not typically associated with sensory processing.

The researchers designed an experiment that induces an auditory illusion in both healthy participants and participants with schizophrenia. They examined how building up or breaking down sensory expectations can modify the strength of this illusion. They also measured dopamine release before and after administering a drug that stimulates the release of dopamine.

Patients with hallucinations tended to perceive sounds in a way that was more similar to what they had been cued to expect, even when sensory expectations were less reliable and illusions weakened in healthy participants. This tendency to inflexibly hear what was expected was worsened after giving a dopamine-releasing drug, and more pronounced in participants with elevated dopamine release, and more apparent in participants with a smaller dorsal anterior cingulate (a brain region previously shown to track reliability of environmental cues). All people have some perceptual distortions, but these results suggest that excess dopamine can exacerbate human distorted perceptions
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Gocovri drug for treatment of dyskinesia

Gocovri (amantadine) drug has been approved for treatment of dyskinesia in patients with Parkinson's disease receiving levodopa-based therapy, with or without concomitant dopaminergic medications.

Gocovri is a high dose 274 mg amantadine (equivalent to 340 mg amantadine HCl) taken once-daily at bedtime that delivers consistently high levels of amantadine from the morning and throughout the day when dyskinesia occurs.

Parkinson's disease is a chronic neurodegenerative disorder. It results from a loss of dopamine in the brain and is commonly treated by levodopa and dopaminergic therapies that replace lost dopamine.

Dyskinesia is a consequence of levodopa-based Parkinson's disease treatment and is characterized by involuntary and non-rhythmic movements that are purposeless and unpredictable, which impact the activities of daily living.

Common adverse reactions of Gocovri are: hallucinations, dizziness, dry mouth, peripheral edema, constipation, fall and orthostatic hypotension.
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