Drugs Used To Treat Parkinson's Disease

There are several drugs used to help manage the symptoms of Parkinson’s disease (PD). While there is no known cure for PD or any known treatments that can slow the progression of the disease, current research seeks to find ways to stop the progression.1,2

Treatment is highly customized to meet the unique needs of each person since no 2 people with PD are alike. Treatment for PD is focused on:1,2

  • Relieving or controlling the symptoms of PD for as long as possible
  • Reducing side effects from treatment
  • Improving quality of life

Drugs for Parkinson's disease

There are several different classes of drugs used to treat the symptoms of PD, including:1,2

  • Dopamine therapy, notably carbidopa-levodopa therapy
  • Dopamine receptor agonists
  • Anticholinergics
  • MAO-B (monoamine oxidase-B) inhibitors
  • COMT (catechol-O-methyltransferase) inhibitors
  • Amantadine, a mild NMDA receptor antagonist

It is important for people with PD to see a movement disorders specialist who is trained in the use of these drugs for PD. They understand the interactions of these drugs and how some drugs may make symptoms worse.

Diagram showing how medications to treat Parkinson's, including levadopa, dopamine agonists, COMT inhibitors, and MAO-B inhibitors, work in the body

Carbidopa-levodopa therapy

The motor symptoms of Parkinson’s are caused by a lack of the neurotransmitter dopamine in the brain. This causes symptoms like:1,2

Dopamine is the chemical messenger that is responsible for smooth, purposeful movement. The main drug treatments used for PD help increase dopamine levels in the brain. By doing so, they relieve the symptoms of PD. The combination of levodopa and carbidopa is the most effective treatment available to manage the motor symptoms of PD.1,2

Dopamine receptor agonists

Dopamine receptor agonists mimic dopamine in the brain. This causes neurons in the brain to use the dopamine agonists instead of dopamine. This can provide relief from symptoms of PD, especially motor symptoms like tremor, rigidity, impaired balance, and loss of spontaneous movement.3

These drugs are not as effective on the motor symptoms of PD as carbidopa-levodopa therapy. However, they may have fewer side effects.3

Anticholinergics

Anticholinergics block the action of acetylcholine. This is another neurotransmitter involved in messages from the brain to the muscles. Anticholinergics are often used along with other treatments for PD.4,5

MAO-B inhibitors

MAO is an enzyme found throughout the cells in the body. In the brain, MAO-B plays an important role in the breakdown of neurotransmitters (chemical messengers) like dopamine. MAO inhibitors block the action of the enzyme. Adding an MAO-B inhibitor to levodopa therapy slows the breakdown of levodopa and dopamine in the brain. This may boost the effect of levodopa.3,6

COMT inhibitors

COMT is an enzyme that breaks down neurotransmitters like dopamine. COMT inhibitors block the action of the COMT enzyme. Adding a COMT inhibitor to levodopa therapy slows the breakdown of levodopa and dopamine. This may boost the effect of levodopa by making more of it available in the brain.7,8

Amantadine

Amantadine is a weak, uncompetitive antagonist of the N-methyl-D-aspartate (NMDA) receptor. While the exact way Amantadine works is not fully understood, scientists think the drug may increase dopamine release and block dopamine reuptake in the brain. This may provide relief from symptoms of PD, especially dyskinesias and tremors.9,10

Other drugs for Parkinson's disease

Other drugs that may be used by people PD include those that treat specific symptoms, including:3

Not all antipsychotic drugs are considered safe for people with PD. However, there are several that can help limit the worsening of PD symptoms and treat symptoms of hallucination and delusion.3

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Written by: Emily Downward | Last reviewed: May 2021