Stephen E. Grill, MD, PHD, responds:
There's no reason to delay taking levodopa, which is effective for treating the symptoms of Parkinson's disease. In fact, the evidence supports treating people early, rather than waiting and risking greater impairment and disability.
In Parkinson's disease, the brain's dopamine levels decline, causing stiffness, slowness, and tremors. Nerve cells use levodopa to replenish the dopamine levels and treat motor symptoms. When people take levodopa, the drug stays in their system for a few hours. When the medication tapers off, symptoms return.
Changing Intervals
In early stages of the disease, people can take levodopa at, say, five-hour intervals, which will keep them "on" for the whole day. But as their disease progresses, they become more sensitive to fluctuations in the level of the drug in the blood and brain. They may start to experience off times after two or three hours and have to take the medicine more frequently, sometimes as often as every two hours.
After about five years, approximately 50 percent of people taking levodopa develop these fluctuations. People in their 40s or 50s have about an 80 percent risk of developing on-off times after five years. Older people in their 70s or 80s have less risk; their disease is generally more stable.
Involuntary Movements
As people take levodopa over extended periods of time, they may also experience involuntary movements known as dyskinesias; these occur when dopamine levels are too high. To delay dyskinesias, doctors may prescribe another class of drugs called dopamine agonists, which mimic the effects of dopamine. However, existing research is unclear on whether taking levodopa hastens dyskinesia compared with dopamine agonists. Doctors also sometimes use dopamine agonists as an add-on therapy, to help smooth out fluctuations.
Additional Options
It is important that doctors and patients work together to determine just the right dose and dosing interval. In some cases, doctors might prescribe a "helper" medicine such as rasagiline (Azilect), selegiline (Eldepryl), entacapone (Comtan), or carbidopa/levodopa/entacapone (Stalevo), which slows the breakdown of dopamine in the brain so the levodopa doesn't wear off as quickly.
New longer-acting medicines such as carbidopa/levodopa (Rytary), a version of levodopa recently approved by the US Food and Drug Administration, last about four or five hours. People who have to take levodopa at two-hour intervals may be able to take this new longer-lasting version at four- or five-hour intervals again.
Dr. Grill is co-founder of the Parkinson's and Movement Disorders Center of Maryland and a member of the Amerian Academy of Neurology. He is affiliated with the Sinai Hospital of Baltimore, the Johns Hopkins Hospital, and the Howard County General Hospital.
