Parkinson's Disease: Levodopa Versus Dopamine Agonists
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.
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.
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.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 and
hallucinations 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
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
Katzenschlager R, et al. (2008). Fourteen-year final
report of the randomized PDRG-UK trial comparing three initial treatments in
PD. Neurology, 71(7): 474?480.
How this information was developed to help you make better health decisions.