Monoamine precursor

[1][2] 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).

[3] Carbidopa/levodopa and levodopa/benserazide are used to increase brain dopamine levels in the treatment of Parkinson's disease.

[3] Carbidopa/oxitriptan (EVX-101), which increases brain serotonin levels, is under development as an antidepressant for possible use in the treatment of depression.

[4][5] Droxidopa (L-DOPS) is a synthetic precursor or prodrug of norepinephrine used orally in the treatment of certain types of hypotension and other conditions.

[6][7] Dipivefrine is a synthetic precursor or prodrug of epinephrine used as an ophthalmic medication.