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Information |
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Drug Groups
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experimental |
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Description
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5-Hydroxytryptophan (5-HTP), also known as oxitriptan (INN), is a naturally occurring amino acid and chemical precursor as well as a metabolic intermediate in the biosynthesis of the neurotransmitters serotonin and melatonin from tryptophan. 5-HTP is sold over-the-counter in the United Kingdom, United States and Canada as a dietary supplement for use as an antidepressant, appetite suppressant, and sleep aid, and is also marketed in many European countries for the indication of major depression under trade names like Cincofarm, Levothym, Levotonine, Oxyfan, Telesol, Tript-OH, and Triptum. Several double-blind placebo-controlled clinical trials have demonstrated the effectiveness of 5-HTP in the treatment of depression, though a lack of high quality studies has been noted. More and larger studies are needed to determine if 5-HTP is truly effective in treating depression. |
| Indication |
For use as an antidepressant, appetite suppressant, and sleep aid. |
| Pharmacology |
The psychoactive action of 5-HTP is derived from its effect on the production of serotonin in central nervous system tissue. More specifically, 5-HTP increases the production of serotonin. |
| Affected Organisms |
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Humans and other mammals |
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| Biotransformation |
5-Hydroxytryptophan is decarboxylated to serotonin (5-hydroxytryptamine or 5-HT) by the enzyme aromatic-L-amino-acid decarboxylase with the help of vitamin B6. This reaction occurs both in nervous tissue and in the liver. |
| References |
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Turner EH, Blackwell AD: 5-Hydroxytryptophan plus SSRIs for interferon-induced depression: synergistic mechanisms for normalizing synaptic serotonin. Med Hypotheses. 2005;65(1):138-44.
[Pubmed]
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Shaw K, Turner J, Del Mar C: Tryptophan and 5-hydroxytryptophan for depression. Cochrane Database Syst Rev. 2002;(1):CD003198.
[Pubmed]
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Rahman MK, Nagatsu T, Sakurai T, Hori S, Abe M, Matsuda M: Effect of pyridoxal phosphate deficiency on aromatic L-amino acid decarboxylase activity with L-DOPA and L-5-hydroxytryptophan as substrates in rats. Jpn J Pharmacol. 1982 Oct;32(5):803-11.
[Pubmed]
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Nakatani Y, Sato-Suzuki I, Tsujino N, Nakasato A, Seki Y, Fumoto M, Arita H: Augmented brain 5-HT crosses the blood-brain barrier through the 5-HT transporter in rat. Eur J Neurosci. 2008 May;27(9):2466-72.
[Pubmed]
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Bouchard S, Roberge AG: Biochemical properties and kinetic parameters of dihydroxyphenylalanine--5-hydroxytryptophan decarboxylase in brain, liver, and adrenals of cat. Can J Biochem. 1979 Jul;57(7):1014-8.
[Pubmed]
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Amamoto T, Sarai K: On the tryptophan-serotonin metabolism in manic-depressive disorders. Changes in plasma 5-HT and 5-HIAA levels and urinary 5-HIAA excretion following oral loading of L-5HTP in patients with depression. Hiroshima J Med Sci. 1976 Sep;25(2-3):135-40.
[Pubmed]
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Magnussen I, Jensen TS, Rand JH, Van Woert MH: Plasma accumulation of metabolism of orally administered single dose L-5-hydroxytryptophan in man. Acta Pharmacol Toxicol (Copenh). 1981 Sep;49(3):184-9.
[Pubmed]
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Birdsall TC: 5-Hydroxytryptophan: a clinically-effective serotonin precursor. Altern Med Rev. 1998 Aug;3(4):271-80.
[Pubmed]
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Sternberg EM, Van Woert MH, Young SN, Magnussen I, Baker H, Gauthier S, Osterland CK: Development of a scleroderma-like illness during therapy with L-5-hydroxytryptophan and carbidopa. N Engl J Med. 1980 Oct 2;303(14):782-7.
[Pubmed]
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Caruso I, Sarzi Puttini P, Cazzola M, Azzolini V: Double-blind study of 5-hydroxytryptophan versus placebo in the treatment of primary fibromyalgia syndrome. J Int Med Res. 1990 May-Jun;18(3):201-9.
[Pubmed]
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Trouillas P, Serratrice G, Laplane D, Rascol A, Augustin P, Barroche G, Clanet M, Degos CF, Desnuelle C, Dumas R, et al.: Levorotatory form of 5-hydroxytryptophan in Friedreich's ataxia. Results of a double-blind drug-placebo cooperative study. Arch Neurol. 1995 May;52(5):456-60.
[Pubmed]
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Birdsall TC: 5-Hydroxytryptophan: a clinically-effective serotonin precursor. Altern Med Rev. 1998 Aug;3(4):271-80.
[Pubmed]
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De Benedittis G, Massei R: Serotonin precursors in chronic primary headache. A double-blind cross-over study with L-5-hydroxytryptophan vs. placebo. J Neurosurg Sci. 1985 Jul-Sep;29(3):239-48.
[Pubmed]
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