monoamine precursor

File:L-Tryptophan - L-Tryptophan.svg, a precursor of serotonin and melatonin and an example of a monoamine precursor.]]

Monoamine precursors are precursors of monoamines and monoamine neurotransmitters in the body.{{Cite book|url=https://books.google.com/books?id=KDxUfc-rEs8C&pg=PA472|title = Food and Nutrients in Disease Management|isbn = 9781420067637|last1 = Kohlstadt|first1 = Ingrid|date = 19 April 2016| publisher=CRC Press }}{{Cite book|url=https://books.google.com/books?id=-chW0k3aFXMC&pg=PA364|title = Inborn Metabolic Diseases: Diagnosis and Treatment|isbn = 9783540287858|last1 = Fernandes|first1 = John|last2 = Saudubray|first2 = Jean-Marie|last3 = Berghe|first3 = Georges van den|last4 = Walter|first4 = John H.|date = 22 November 2006| publisher=Springer }} The amino acids L-tryptophan and L-5-hydroxytryptophan (5-HTP; oxitriptan) are precursors of serotonin and melatonin, while the amino acids L-phenylalanine, L-tyrosine, and L-DOPA (levodopa) are precursors of dopamine, epinephrine (adrenaline), and norepinephrine (noradrenaline).

Administration of monoamine precursors can increase the levels of monoamine neurotransmitters in the body and brain. Monoamine precursors may be used in combination with peripherally selective aromatic L-amino acid decarboxylase inhibitors (AAAD inhibitors; also known as DOPA decarboxylase (DDC) inhibitors) such as carbidopa and benserazide to restrict metabolism and activation in the periphery.{{cite journal | vauthors = Salat D, Tolosa E | title = Levodopa in the treatment of Parkinson's disease: current status and new developments | journal = J Parkinsons Dis | volume = 3 | issue = 3 | pages = 255–69 | date = January 2013 | pmid = 23948989 | doi = 10.3233/JPD-130186 | url = | doi-access = free }} Carbidopa/levodopa and levodopa/benserazide are used to increase brain dopamine levels in the treatment of Parkinson's disease. Carbidopa/oxitriptan (EVX-101), which increases brain serotonin levels, is under development as an antidepressant for possible use in the treatment of depression.{{cite journal | vauthors = Turner EH, Loftis JM, Blackwell AD | title = Serotonin a la carte: supplementation with the serotonin precursor 5-hydroxytryptophan | journal = Pharmacol Ther | volume = 109 | issue = 3 | pages = 325–338 | date = March 2006 | pmid = 16023217 | doi = 10.1016/j.pharmthera.2005.06.004 | url = https://escholarship.org/uc/item/58h866d5}}{{Cite web|url=https://adisinsight.springer.com/drugs/800052771|title=Carbidopa/Oxytriptan - Evecxia - AdisInsight}}

Droxidopa (L-DOPS) is a synthetic precursor or prodrug of norepinephrine used orally in the treatment of certain types of hypotension and other conditions.{{cite journal | vauthors = Goldstein DS | title = L-Dihydroxyphenylserine (L-DOPS): a norepinephrine prodrug | journal = Cardiovasc Drug Rev | volume = 24 | issue = 3–4 | pages = 189–203 | date = 2006 | pmid = 17214596 | doi = 10.1111/j.1527-3466.2006.00189.x | url = }} Dipivefrine is a synthetic precursor or prodrug of epinephrine used as an ophthalmic medication.{{cite journal | vauthors = Scott KA, Cox PB, Njardarson JT | title = Phenols in Pharmaceuticals: Analysis of a Recurring Motif | journal = J Med Chem | volume = 65 | issue = 10 | pages = 7044–7072 | date = May 2022 | pmid = 35533692 | doi = 10.1021/acs.jmedchem.2c00223 | url = https://par.nsf.gov/servlets/purl/10332412}}