L-DOPA

L-DOPA (levodopa, 3,4-dihydroxy-L-phenylalanine). As a drug it is used to treat Parkinson's disease.

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L-DOPA is used to replace dopamine lost in Parkinson's disease because dopamine itself cannot cross the blood-brain barrier where its precursor can. However, L-DOPA is converted to dopamine in the periphery as well as in the CNS, so it is administered with a peripheral DDC (dopamine decarboxylase) inhibitor such as carbidopa, without which 90% is metabolised in the gut wall, and with a COMT inhibitor if possible; this prevents about a 5% loss. The form given therapeutically is therefore a prodrug which avoids decarboxylation in the stomach and periphery, can cross the blood-brain barrier, and once in the brain is converted to the neurotransmitter dopamine by the enzyme aromatic-L-amino-acid decarboxylase.

Hydroxy: In chemical nomenclature, the prefix hydroxy indicates the presence of a hydroxyl functional group (-OH). Such groups are found in alcohols, phenols, and carboxylic acids and as ligands in inorganic compounds....

Parkinson's disease: Parkinson's disease (PD; paralysis agitans) is a neurodegenerative disease of the substantia nigra (an area in the basal ganglia of the brain). The disease was first discovered and its symptoms documented in 1817 (An Essay on the Shaking Palsy) by the British physician Dr. James Parkinson; the asso...

Dopamine: Dopamine is a chemical naturally produced in the body. In the brain, dopamine functions as a neurotransmitter, activating dopamine receptors. Dopamine is also a neurohormone released by the hypothalamus. Its main function as a hormone is to inhibit the release of prolactin from the anterior lobe of...