Levodopa
Levodopa (Laradopa), the most effective antiparkinson drug available, an oral drug introduced in 1967 that treats bradykinesia, rigidity, tremor, and difficulty walking. Levodopa’s structure enables it to enter the brain, where it transforms into dopamine.
When levodopa is taken alone, however, the body breaks down about 95 percent of the drug into dopamine before it reaches the brain. Instead of being used by the brain, the dopamine travels throughout the body, producing side effects, including nausea and vomiting, before it is broken down, or metabolized, by the liver and other tissues. Combining levodopa with a drug such as carbidopa enables more levodopa to enter the brain before it converts into dopamine. Carbidopa/levodopa (Atamet, Sinemet) lessens rigidity and bradykinesia but is less effective in treating tremor or balance problems. A similar drug combining carbidopa and benserazide (Madopar) is available in Canada and Europe.
Carbidopa/levodopa produces side effects in some people. As many as half of the people who take this drug for two to five years begin to notice fluctuations in the drug’s effectiveness, known as an on-off effect. Others develop dyskinesia—involuntary movements such as jerking or twitching. As Parkinson disease progresses, the effectiveness of carbidopa/levodopa decreases and patients need higher and more frequent doses to control their symptoms. Depending upon the severity of symptoms, most doctors combine carbidopa/levodopa with other drugs to enhance levodopa’s effects.
When levodopa is taken alone, however, the body breaks down about 95 percent of the drug into dopamine before it reaches the brain. Instead of being used by the brain, the dopamine travels throughout the body, producing side effects, including nausea and vomiting, before it is broken down, or metabolized, by the liver and other tissues. Combining levodopa with a drug such as carbidopa enables more levodopa to enter the brain before it converts into dopamine. Carbidopa/levodopa (Atamet, Sinemet) lessens rigidity and bradykinesia but is less effective in treating tremor or balance problems. A similar drug combining carbidopa and benserazide (Madopar) is available in Canada and Europe.
Carbidopa/levodopa produces side effects in some people. As many as half of the people who take this drug for two to five years begin to notice fluctuations in the drug’s effectiveness, known as an on-off effect. Others develop dyskinesia—involuntary movements such as jerking or twitching. As Parkinson disease progresses, the effectiveness of carbidopa/levodopa decreases and patients need higher and more frequent doses to control their symptoms. Depending upon the severity of symptoms, most doctors combine carbidopa/levodopa with other drugs to enhance levodopa’s effects.
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