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l-dopa(ĕl-dō`pə), drug used to alleviate some of the symptoms of Parkinson's diseaseParkinson's disease
degenerative brain disorder first described by the English surgeon James Parkinson in 1817. When there is no known cause, the disease usually appears after age 40 and is referred to as Parkinson's disease; a number of genes have
..... Click the link for more information. , particularly trembling, rigidity, and slow movements; the drug is also called levodopa. Parkinson's disease results when the concentration of dopamine in the brain is depleted (see catecholaminecatecholamine
, any of several compounds occurring naturally in the body that serve as hormones or as neurotransmitters in the sympathetic nervous system. The catecholamines include such compounds as epinephrine, or adrenaline, norepinephrine, and dopamine.
..... Click the link for more information. ). Medical administration of dopamine itself is ineffective since that chemical apparently does not enter the brain from the blood. A metabolic precursor of dopamine, l-dopa does enter the brain via the bloodstream and is probably converted into dopamine there. Because there are many brain disorders with similar symptoms, many patients do not show any improvement when treated with the drug. Furthermore, virtually all patients on l-dopa experience side effects including nausea, loss of appetite, cardiac irregularities, and psychological changes.