Parkinson's Disease: Levodopa Versus Dopamine Agonists

Topic Overview

No known treatment can stop or reverse the breakdown of nerve cells that causes Parkinson's disease. But medicine can relieve many symptoms of the disease.

Treatment is different for every person. And the type of treatment you will need may change as the disease progresses. Your age, work status, family, and living situation can all affect decisions about when to begin treatment, what types of treatment to use, and when to make changes in treatment. As your medical condition changes, you may need regular adjustments in your treatment to balance quality-of-life issues, side effects of treatment, and treatment costs.

The decision to start taking medicine, and which medicine to take, will be different for each person with Parkinson's disease. Your doctor will be able to help you make these choices.

For many years, levodopa has been the drug of choice for treating Parkinson's disease. Although many newer drugs have been developed, including the dopamine agonists (for example, pramipexole), levodopa is still considered the most effective drug for relieving the widest range of symptoms. It helps reduce tremor, stiffness, and slowness. And it helps improve muscle control, balance, and walking.

When dopamine agonists are used alone, they are helpful in relieving most symptoms of early Parkinson's disease, especially those that affect motor function (such as stiffness and slowness). They are not as effective as levodopa in controlling tremor and other symptoms. And they tend to have more side effects than levodopa.

Because levodopa controls the symptoms of Parkinson's disease so well-and with so few side effects at the beginning-there is some benefit for people who start treatment with levodopa, rather than with a dopamine agonist. A person with Parkinson's disease who starts treatment with levodopa may have more early years with better control of symptoms and fewer side effects.

But it also is well documented that most people who take levodopa develop motor problems (motor fluctuations) within 5 to 10 years after starting the medicine. These complications-unpredictable swings in motor control between doses and uncontrollable jerking or twitching (dyskinesias)-can be hard to manage and can become as disabling as some of the problems caused by the disease itself. But in the longest study done, people who started treatment with a dopamine agonist had just as many problems with motor fluctuations at 14 years as people who started treatment with levodopa.^{footnote 1}

In an effort to delay the development of motor fluctuations, many doctors are now starting people with early Parkinson's disease on a dopamine agonist rather than levodopa. A dopamine agonist may be used until it no longer adequately relieves symptoms, at which point the person starts taking levodopa in addition to the dopamine agonist. (Dopamine agonists can also cause severe sleep problems, hallucinations, and impulse control issues in some people. Having these side effects may be another reason to switch to levodopa.) As long as the person's symptoms are adequately controlled and he or she can tolerate the drug, dopamine agonists may be a good choice for treating early Parkinson's disease.

This approach is being used particularly in younger people with Parkinson's disease, because it can delay the need for levodopa and thus may postpone the motor fluctuations that occur with long-term levodopa therapy. The American Academy of Neurology now recommends this course of treatment for most people with early Parkinson's disease, regardless of their age.

Still, most people with Parkinson's disease eventually need to take levodopa to control their symptoms, even if they initially begin treatment with a dopamine agonist. Levodopa continues to offer the strongest and most immediate relief of Parkinson's symptoms.

As the disease progresses and motor fluctuations become more severe, medicines may be used together. And your doctor may change the amount and type of medicines you are taking.