Levodopa has long been proven to provide the greatest relief of all available medications in the treatment of Parkinson's disease. It also is the most cost-effective drug for managing the full range of problems associated with this chronic neurological disorder, which affects an estimated one million Americans.
In the Dec. 4 issue of the New England Journal of Medicine, Henry Ford Hospital neurologist Peter A. LeWitt, M.D., writes that levodopa should be used not only for treating both early and advanced stages of Parkinson's disease, but also for confirming a suspected diagnosis of Parkinson's disease.
"Within a few minutes after taking an oral dose of levodopa, a patient can recover from previous impairments in speech, dexterity and gait," says LeWitt. "Though the start of levodopa can be postponed if the clinical manifestations of Parkinson's disease are mild and tolerable, it may be the only effective option to control discomfort and disability even for mildly affected patients."
Affecting 1 to 2 percent of the population over the age of 60, Parkinson's disease is a degenerative disorder of the central nervous system that causes tremors and impairs a person's motor skills, speech, balance and posture. Its cause is unknown, but many clues are guiding clinical trials.
A small region deep within the brain is the source for the symptoms of Parkinson's disease. When brain neurons in this part of the brain begin to die, these cells can no longer manufacture the molecule dopamine, a chemical critical for controlling movement. Levodopa replaces the deficient dopamine, reversing most features of Parkinson's disease.
Among patients with Parkinson's disease, the pace and extent of progression in neurologic deficits can greatly vary. The burden on quality of life spans a wide spectrum too, Dr. LeWitt says, from minimal discomfort and disability to marked impairment of capabilities such as independence, safety and communication.
While it is shown to improve motor impairments, levodopa often does not provide relief from the tremors and can cause involuntary movements and other side effects, requiring physicians to carefully re-assess the treatment regimen.
In the first few weeks of use, the dose of levodopa given to the patient may need to be adjusted to achieve maximum benefit. Over time, levodopa dosing often needs to be tailored to a patient's needs, sometimes in combination with other medications to optimize its effects.
"Although available controlled-release preparations are designed for more extended drug delivery, they generally do not achieve the same effects as immediate-release tablets taken closer together," writes Dr. LeWitt.
- LeWitt PA. Levodopa for the treatment of Parkinson's disease. N Engl J Med, 2008; 359: 2468-2476
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