A variety of medications are available to treat the symptoms of Parkinson’s disease. Treatment typically begins when symptoms start to affect a person’s functioning. All of the available medications have side effects, and over time they become less effective. Specialized surgery can help certain individuals. Ultimately, the disease worsens despite treatment.
Medication for Early Movement Symptoms
People with Parkinson’s disease lose brain cells that make the chemical dopamine, which the brain uses to send signals about movement. The drug carbidopa-levodopa (Sinemet, Parcopa) can help replace some of the missing dopamine and is the most effective treatment for the movement symptoms. But people who use carbidopa-levodopa long-term may develop dyskinesias, or abnormal involuntary movements. To try to avoid this, some begin treatment with a different type of drug called dopamine agonists, such as pramipexole (Mirapex), ropinirole (Requip) and the rotigotine patch (Neupro). These drugs make the brain think dopamine is present and are less likely to cause dyskinesias. But they don’t treat the movement symptoms as well and can have side effects like sleepiness, swelling of the limbs or hallucinations. Another medication option is the class called MAO-B inhibitors, including selegiline (Eldepryl) or rasagiline (Azilect), that help the brain use dopamine more effectively. Like dopamine agonists, these drugs are less likely to cause dyskinesias, but they are also less effective for the movement symptoms. Once a person develops dyskinesias, the drug amantadine may help.
The tremor of Parkinson’s disease is sometimes treated with drugs affecting a different brain chemical — acetylcholine. These include benzatropine (Cogentin) and trihexyphenidyl (Artane). Because of their side effects, they are typically recommended for people under age 60 who do not have thinking problems. The drug amantadine is also sometimes used for tremor but carries its own side effects.
Medication for Late-Movement Symptoms
As Parkinson’s disease progresses, people experience motor fluctuations — changes in movement symptoms that occur when medications become less effective. When movement symptoms return, either gradually or suddenly, it is known as “off-time.” Drugs that reduce “off-time” by helping the brain use dopamine more effectively include rasagiline (Azilect), an MAO-B inhibitor, and entacapone (Comtan), a COMT inhibitor. These drugs are both tablets that must be taken daily. For immediate, short-lived relief of “off-time” symptoms, the dopamine agonist apomorphine can be injected beneath the skin. Motor fluctuations may also improve with a form of carbidopa-levodopa (Duopa) that is continuously infused through a surgically implanted tube in the stomach, but this carries the risks of surgery and infection.
Medication for Non-Movement Symptoms
People with Parkinson’s disease experience a host of non-movement symptoms due to loss of dopamine and other important brain chemicals. Sleep-related symptoms include REM sleep behavior disorder, in which people act out vivid or frightening dreams. This may improve with a low dose of the drug clonazepam (Klonopin). Restless legs syndrome — an uncomfortable sensation in the legs that cause a need to move them — can improve with carbidopa-levodopa at bedtime. Fatigue may improve with methylphenidate (Ritalin). Constipation can be treated with polyethylene glycol (Miralax), and sildenafil (Viagra) can treat erectile dysfunction. For problems with thinking, which when severe are known as dementia, the drug rivastigmine (Exelon, Exelon patch) may help. Problems like depression can be treated with the dopamine agonist pramipexole or other drugs more typically used to treat depression. Hallucinations — seeing things that aren’t there — are treated with the drugs quetiapine (Seroquel, Seroquel XR) or clozapine, which requires special monitoring due to a potentially dangerous effect on white blood cells.
Deep Brain Stimulation
As Parkinson’s disease progresses, medications may be unable to control a person’s symptoms, such as dyskinesias, tremor or fluctuations in their slowed movement and muscle stiffness. People under the age of 70 who don’t have dementia and who respond well to levodopa may benefit from specialized surgery. The surgery involves placing electrodes called “deep brain stimulators” inside a specific area of the brain. The electrodes send a signal that helps to activate movement. The person with the deep brain stimulator can turn it off when they want. Risks of surgery include infection, bleeding or blood clots in the brain, falls and depression. It also does not slow the progression of Parkinson’s disease.
Warnings and Precautions
Medications for Parkinson’s disease can have a variety of side effects, some of which can be serious, so it is important to share any new symptoms you experience with your health care provider. It is also important to let your provider know about any other medications, supplements or vitamins that you are taking.