Monoamine precursor

Monoamine precursors are precursors of monoamines and monoamine neurotransmitters in the body.^[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).^[1][2]

L-Tryptophan, a precursor of serotonin and melatonin and an example of a monoamine precursor.

Administration of monoamine precursors can increase the levels of monoamine neurotransmitters in the body and brain.^[2] 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.^[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.^[7]

See also

• Neurotransmitter prodrug