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20-September-2008 09:55:50 - L-DOPA Redirected from Levodopa L-DOPA Systematic IUPAC name S-2-amino-3-3,4-dihydroxyphenyl propanoic acid Identifiers CAS number 59-92-7 ATC code N04 PubChem 6047 DrugBank APRD00309 Chemical data Formula C9H11NO4 Mol. mass 197.19 g/mol Pharmacokinetic data Bioavailability 30% Metabolism Aromatic-L-amino-acid decarboxylase Half life 0.75-1.5 hours Excretion renal 70-80% Therapeutic considerations Pregnancy cat. B3AU CUS Legal status OTC Routes oral L-DOPA 3,4-dihydroxy-L-phenylalanine is an intermediate in dopamine biosynthesis. In clinical use, Levodopa INN is administered in the management of Parkinson's disease. It is also used as a component in marine adhesives used by pelagic life. Contents 1 Therapeutic use 2 Adverse effects 2.1 Toxicity 3 Biosynthesis 4 History 5 Supplements containing L-DOPA 6 Adhesion 7 Melanin formation 8 References 8.1 Footnotes 8.2 General references 9 External links Therapeutic use Levodopa is used as a prodrug to increase dopamine levels for the treatment of Parkinson's disease, since it is able to cross the blood-brain barrier, whereas dopamine itself cannot. Once levodopa has entered the central nervous system CNS, it is metabolized to dopamine by aromatic L-amino acid decarboxylase. Pyridoxal phosphate vitamin B6 is a required cofactor for this decarboxylation, and may be administered along with levodopa, usually as pyridoxine. Conversion to dopamine also occurs in the peripheral tissues, i.e. outside the brain. This is the primary mechanism of the adverse effects of levodopa. It is standard clinical practice to co-administer a peripheral DOPA decarboxylase inhibitor-carbidopa or benserazide-and often a catechol-O-methyl transferase COMT inhibitor, to prevent synthesis of dopamine in peripheral tissue. Co-administration of pyridoxine without a decarboxylase inhibitor accelerates the extracerebral decarboxylation to such an extent that it cancels out the effects of levodopa administration, a circumstance which historically caused great confusion. Levodopa, co-administered with a peripheral DOPA decarboxylase inhibitor, has been tested as a possible treatment for restless leg syndrome RLS.1 Adverse effects Possible adverse drug reactions include: Hypotension, especially if the dosage is too high Arrhythmias, although these are uncommon Nausea, which is often helped by taking the drug with food, although protein interferes with drug absorption Gastrointestinal bleeding Disturbed respiration, which is not always harmful, and can actually benefit patients with upper airway obstruction Hair loss Confusion Extreme emotional states, particularly anxiety, but also excessive libido Vivid dreams and/or fragmented sleep Visual and possibly auditory hallucinations Effects on learning; there is some evidence that it improves working memory, while impairing other complex functions Sleepiness and sleep attacks A condition similar to amphetamine psychosis. Although there are many adverse effects associated with levodopa, particularly psychiatric ones, it has fewer than other anti-Parkinson's drugs, including anticholinergics, amantadine, and dopamine agonists. More serious are the effects of chronic levodopa administration, which include: End-of-dose deterioration of function On/off oscillations Freezing during movement Dose failure drug resistance Dyskinesia at peak dose. Clinicians will try to avoid these by limiting levodopa dosages as far as possible until absolutely necessary. Toxicity Some studies suggest a cytotoxic role in the promotion and occurrence of adverse effects associated with levodopa treatment.2 Though the drug is generally safe in humans, some researchers have reported an increase in cytotoxicity markers in rat pheochromocytoma PC12 cell lines treated with levodopa.3 Other authors have attributed the observed toxic effects of levodopa in neural dopamine cell lines to enhanced formation of quinones through increased auto-oxidation and subsequent cell death in mesencephalic cell cultures.45 Though levodopa is generally considered safe, some controversy surrounds use of the drug in Parkinson's Disease given some data indicating a deleterious effect on intracellular and neuronal tissue involved in the pathogenesis of the disease.6 Biosynthesis Biosynthesis of Dopamine Biosynthesis of Dopamine L-DOPA is produced from the amino acid tyrosine by the enzyme tyrosine hydroxylase. It is also the precursor molecule for the catecholamine neurotransmitters dopamine and norepinephrine noradrenaline, and the hormone epinephrine adrenaline. Dopamine is formed by the decarboxylation of L-DOPA. L-DOPA can be directly metabolized by catechol-O-methyl transferase COMT to 3-O-methyldopa 3-OMD and then further to vanillactic acid VLA. This metabolic pathway is non-existent in the healthy body but becomes important after peripheral L-DOPA administration in patients with Parkinson's Disease or in the rare cases of patients with aromatic L-amino acid decarboxylase AADC enzyme deficiency. 7 The prefix L- references its property of levorotation compared with dextrorotation or D-DOPA. History In work that earned him a Nobel Prize in 2000, Swedish scientist Arvid Carlsson first showed in the 1950s that administering levodopa to animals with Parkinsonian symptoms would cause a reduction of the symptoms. The neurologist Oliver Sacks describes this treatment in human patients with encephalitis lethargica in his book Awakenings, upon which the movie of the same name is based. The 2001 Nobel Prize in Chemistry was also related to L-DOPA: the Nobel Committee awarded one-fourth of the prize to William S. Knowles for his work on chirally-catalysed hydrogenation reactions, the most noted example of which was used for the synthesis of L-DOPA. Supplements containing L-DOPA Herbal supplements containing standardized dosages of L-DOPA are available without a prescription. These supplements have recently increased in both availability and popularity in the United States and on the internet. The most common plant source of L-DOPA marketed in this manner is a tropical legume, Mucuna pruriens, also known as Velvet Bean and by a number of other common names. L-DOPA at 500-1,000 mg will effectively raise HGH levels.citation needed Adhesion DOPA is a key molecule in the formation of marine adhesive proteins, such as those found in mussels. It is believed to be responsible for the water-resistance and rapid curing abilities of these proteins. DOPA may also be used to prevent surfaces from fouling by bonding antifouling polymers to a susceptible substrate. Melanin formation Both levodopa and its precursor amino acid L-tyrosine are precursors to the biological pigment melanin. The enzyme tyrosinase catalyzes the oxidation of L-dopa to the reactive intermediate dopaquinone, which reacts further, eventually leading to melanin oligomers. References Footnotes ^ http://www.medicine.ox.ac.uk/bandolier/booth/RLS/dopa.html ^ Cheng N, Maeda T, Kume T, Kaneko S, Kochiyama H, Akaike A, Goshima Y, Misu Y. Differential neurotoxicity induced by L-DOPA and dopamine in cultured striatal neurons. Brain Research. December, 1996, Vol. 743, No. 1-2, pp. 278-83. PMID: 9017256. ^ Basma AN, Morris EJ, Nicklas WJ, Geller HM. L-dopa cytotoxicity to PC12 cells in culture is via its autoxidation. Journal of Neurochemisty Blackwell Publications. February, 1995, Vol. 164, No. 2, pp. 825-32. PMID: 7830076. ^ Pardo B, Mena MA, Casarejos MJ, PaÃno CL, De Yébenes JG. Toxic effects of L-DOPA on mesencephalic cell cultures: protection with antioxidants. Brain Research June, 1995, Vol. 682, No. 1-2, pp. 133-43. PMID: 7552304. ^ Mytilineou C, Han SK, Cohen G. Toxic and protective effects of L-dopa on mesencephalic cell cultures. Journal of Neurochemistry 1993 Oct;614:1470-8. PMID: 8376999. ^ Simuni T, Stern MB. Does levodopa accelerate Parkinson's disease? Drugs Aging 1999 Jun;146:399-408. PMID: 10408739. ^ Hyland K, Clayton PT 1992. Aromatic L-amino acid decarboxylase deficiency: diagnostic methodology. Clin Chem. 38 12: 2405-10. PMID 1281049. General references Waite, J. Herbert, et al. 2005. Mussel Adhesion: Finding the Tricks Worth Mimicking. J Adhesion 81: 1-21. doi:10.1080/00218460590944602. Messersmith, Phillip B., et al. 2006. Rapid Gel Formation and Adhesion in Photocurable and Biodegradable Block Copolymers with High DOPA Content. Macromolecules 39: 1740-1748. doi:10.1021/ma0518959. External links ScienceDaily: Study Reveals Details Of Mussels' Tenacious Bonds Northwestern University August 16, 2006 v d e Anti-parkinson drugs: dopaminergic agents N04B Dopa and derivatives Droxidopa Levodopa Melevodopa Etilevodopa Adamantane derivatives Amantadine Dopamine agonists A-412,997 Apomorphine Bromocriptine Cabergoline Dihydrexidine Dihydroergocryptine mesylate Fenoldopam Lisuride Pergolide Piribedil Pramipexole Propylnorapomorphine Quinpirole Ropinirole Rotigotine SKF 38393 SKF 82958 MAOIs B Selegiline Rasagiline COMT inhibitors Entacapone Tolcapone Other Budipine dopa decarboxylase inhibitor Carbidopa v d e Amino acid metabolism metabolic intermediates K→acetyl-CoA lysine→ Saccharopine - Allysine - Alpha-aminoadipate - Alpha-ketoadipic acid - Glutaryl-CoA - Glutaconyl-CoA - Crotonyl-CoA - Beta-hydroxybutyryl-CoA leucine→ Alpha-ketoisocaproic acid - Isovaleryl-CoA - 3-Methylcrotonyl-CoA - 3-Methylglutaconyl-CoA - HMG-CoA tryptophan→alanine→ N'-Formylkynurenine - Kynurenine - Anthranilic acid - 3-hydroxykynurenine - 3-Hydroxyanthranilic acid - 2-Amino-3-carboxymuconic semialdehyde - 2-Aminomuconic semialdehyde - 2-Aminomuconic acid - Glutaryl-CoA G→glutamate histidine→ Urocanic acid - Imidazol-4-one-5-propionic acid - Formiminoglutamic acid - Glutamate-1-semialdehyde proline→ 1-Pyrroline-5-carboxylic acid arginine→ Ornithine - Putrescine - Agmatine G→propionyl-CoA methionine→ S-Adenosyl methionine - S-Adenosyl-L-homocysteine - Homocysteine - Cystathionine - alpha-Ketobutyric acid isoleucine→ 2,3-Dihydroxy-3-methylpentanoic acid - 2-Methylbutyryl-CoA - Tiglyl-CoA - 2-methylacetoacetyl-CoA valine→ Alpha-ketoisovalerate - Isobutyryl-CoA - Methacrylyl-CoA - 3-Hydroxyisobutyryl-CoA - 3-Hydroxyisobutyrate - 2-methyl-3-oxopropanoate threonine→ Alpha-ketobutyric acid propionyl-CoA→ Methylmalonyl-CoA G→fumarate phenylalanine→tyrosine→ 4-Hydroxyphenylpyruvic acid - Homogentisic acid - 4-Maleylacetoacetate Other cysteine+glutamate→glutathione gamma-Glutamylcysteine glycine→creatine Glycocyamine - Phosphocreatine - Creatinine Other Glycerate 3-phosphate serine - Cysteine sulfinic acid see also enzymes, disorders Retrieved from http://en..org/wiki/L-DOPA Categories: Dopamine agonists | Psychoactive drugs | Amino acids | ProdrugsHidden categories: All articles with statements | Articles with statements since August 2008 Views Article Discussion this page History Personal tools Log in / create account Navigation Main page Contents Featured content Current events Random article Search Go Search Interaction Community portal Recent changes Contact Donate to Help Toolbox What links here Related changes Upload file Special pages Printable version Permanent link Cite this page Languages Deutsch Eesti Español Français Italiano Magyar Nederlands 日本語 Polski Português РуÑ?Ñ?кий Suomi Svenska This page was last modified on 19 August 2008, at 20:56
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