Parkinson's Disease - Medications

Levadopa (L-dopa)

Levodopa, also called L-dopa, which is converted to dopamine in the brain, remains the gold standard for treating Parkinson's disease. The standard preparations (Sinemet, Atamet) combine levodopa with carbidopa, which improves the action of levodopa and reduces some of its side effects, particularly nausea. Dosages vary, although the preparation is usually taken in three or four divided doses per day.

Indications of Early Treatment Success or Failures

In general L-dopa has the following effects on Parkinson's disease:

• It is most effective against rigidity and slowness.
• It produces less benefit for tremor, balance, and gait.

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In many patients, levodopa significantly improves the quality of life for many years.

Side Effects

The toxic effects of levodopa with or without carbidopa are considerable.

Physical Side Effects. The physical side effects include:

• Dyskinesia. Dyskinesia (the inability to control muscles) is a very distressing side effect of levodopa. Dyskinesia can take many forms, most often uncontrolled flailing of the arms and legs or chorea, rapid and repetitive motions that can affect the limbs, face, tongue, mouth, and neck.
• Low blood pressure (hypotension). Low blood pressure is a common problem during the first few weeks, particularly if the initial dose is too high.
• Arrhythmia. In some cases the drug may cause abnormal heart rhythms.
• Gastrointestinal effects. Stomach and intestinal side effects are common even with carbidopa. Taking the drug with food can alleviate the nausea. However, proteins interfere with intestinal absorption of levodopa, and some doctors recommend not eating any protein until nighttime in order to avoid this interference. The drug can also cause gastrointestinal bleeding.
• Effects in the lung. Levodopa can cause disturbances in breathing function, although it may benefit patients who have upper airway obstruction.
• Hair loss.

Psychiatric and Mental Side Effects. The major adverse effects of the drug are psychiatric. Patients taking levodopa, especially in combination with other drugs, can experience: