Kalamazoo Nerve Center, PLLC

Levodopa (L-dopa)

Levodopa (L-dopa)

Levodopa(also called L-dopa) is the cornerstone of Parkinson's disease treatment. It may also be prescribed for the treatment of other movement disorders, including Restless Leg Syndrome (RLS).

Levodopa is very successful at reducing the tremors, rigidity, slow movement and other early symptoms of Parkinson's disease. It allows the majority of people with levodopa to extend the period of time in which they can lead relatively normal, productive lives.

However, levodopais not a cure for Parkinson's disease. It can reduce the symptoms of Parkinson's disease, but it does not replace lost nerve cells and it does not stop the progression of the disease. And some symptoms, such as balance and other non-motor symptoms may not be alleviated at all.

People who have taken other medications for Parkinson's disease before starting levodopa therapy may have to cut back or eliminate these drugs in order to feel the full benefit of levodopa. People often see dramatic improvement in their symptoms after starting levodopa therapy. However, the dose of levodopa needs to be gradually increased to maintain maximum benefit

How does Levodopa work?

Nerve cells can use levodopa to make dopamine and replenish the brain's dwindling supply.

People cannot simply take dopamine pills because dopamine does not easily pass from the blood into the brain. Levodopa is a form that can be transported into the brain.

A high-protein diet can interfere with the absorption of levodopa, so some physicians recommend that patients taking the drug restrict their protein consumption during the early parts of the day or avoid taking their medications with protein-rich meals.

What are the side effects of Levodopa?

Levodopa can have a variety of side effects. The most common initial side effects include nausea, vomiting, low blood pressure, and restlessness. The drug also can cause drowsiness or sudden sleep onset, which can make driving and other activities dangerous.

Long-term use of levodopa sometimes causes hallucinations and psychosis. The nausea and vomiting caused by levodopa are greatly reduced by combining levodopa and carbidopa, which enhances the effectiveness of a lower dose.

Dyskinesias, or involuntary movements such as twitching, twisting, and writhing, commonly develop in people who take large doses of levodopa over an extended period. These movements may be either mild or severe and either very rapid or very slow. The dose of levodopa is often reduced in order to lessen these drug-induced movements. However, the Parkinson's disease symptoms often reappear even with lower doses of medication. Doctors and patients must work together closely to find a tolerable balance between the drug's benefits and side effects. If dyskinesias are severe, surgical treatment may be considered. Because dyskinesias tend to occur with long-term use of levodopa, doctors often start younger Parkinson's disease patients on other dopamine-increasing drugs and switch to levodopa only when those drugs become ineffective.

Other troubling and distressing problems may occur with long-term levodopa use. Patients may begin to notice more pronounced symptoms before their first dose of medication in the morning, and they may develop muscle spasms or other problems when each dose begins to wear off. The period of effectiveness after each dose may begin to shorten, called the wearing-off effect. Another potential problem is referred to as the on-off effect, sudden, unpredictable changes in movement, from normal to parkinsonian movement and back again. These effects probably indicate that the patient's response to the drug is changing or that the disease is progressing.

One approach to alleviating these side effects is to take levodopa more often and in smaller amounts.  People with Parkinson's disease should never stop taking levodopa without their physician's knowledge or consent because rapidly withdrawing the drug can have potentially serious side effects, such as immobility or difficulty breathing.

If treatment with Levodopa fails to control symptoms, or leads to to many unwanted side effects, other medications may be prescribed, including:

  • Dopamine agonists (bromocriptine, apomorphine, pramipexole (Mirapex®), and ropinirole (Requip®). These medications mimic the role of dopamine in the brain. They can be given alone or in conjunction with levodopa.
  • MAO-B inhibitors (rasagiline (Azilect®), selegeline (Eldepryl®, Zelapar®). These drugs slow down an enzyme in the brain (monoamine oxidase B) which breaks down dopamine.
  • COMT inhibitors (entacapone (Comtan®, Stalevo®) and tolcapone (Tasmar®). COMT are the initials of another enzyme that helps to break down dopamine. These drugs prolong the effects of levodopa by preventing the breakdown of dopamine. COMT inhibitors can decrease the duration of "off" periods, and they usually make it possible to reduce the person's dose of levodopa.
  • Amantadine. An antiviral drug, amantadine, can help reduce symptoms of Parkinson's disease and levodopa-induced dyskinesia. It is often used alone in the early stages of the disease.  It also may be used with an anticholinergic drug or levodopa.
  • Anticholinergics (trihexyphenidyl, benztropine, and ethopropazine). These medications decrease the activity of the neurotransmitter acetylcholine and help to reduce tremors and muscle rigidity.

Reference: National Institute of Neurological Diseases and Stroke (NINDS)