L-dopa

L-DOPA (or levodopa) is a chemical that is made and used as part of the normal biology of humans, some animals and plants. In humans, it is created via biosynthesis from the amino acid L-tyrosine. It is the precursor to several neurotransmitters including dopamine, norepinephrine (noradrenaline), and epinephrine (adrenaline). The prefix L- refers to its property of levorotation (compared with dextrorotation or D-DOPA).

Medical Use

L-DOPA is used in the clinical treatment of Parkinson's disease and dopamine-responsive dystonia. When administered orally, it is rapidly decarboxylated to dopamine in the peripheral tissues and the brain. This conversion is catalyzed by the enzyme aromatic L-amino acid decarboxylase, which is abundant in the peripheral tissues.

Side Effects

Common side effects of L-DOPA treatment include nausea, orthostatic hypotension, and hallucinations. Less common side effects include sleepiness and sudden onset sleep.

Pharmacology

L-DOPA crosses the protective blood–brain barrier, whereas dopamine itself cannot. Thus, L-DOPA is used to increase dopamine concentrations in the treatment of Parkinson's disease and dopamine-responsive dystonia.

History

L-DOPA was first isolated in 1913 from seedlings of Vicia faba, a fava bean. Modern clinical usage began in 1967 after the final trials by a team led by Oliver Sacks.

See Also

• Dopamine
• Parkinson's disease
• Dopamine-responsive dystonia
• Aromatic L-amino acid decarboxylase
• Oliver Sacks

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