Droxidopa is a (-)-threo-3-(3,4-dihydroxyphenyl) derivative of
the natural amino acid, L-serine. In the body, droxidopa is
metabolized by a vitamin B6-dependent enzyme, aromatic amino acid
decarboxylase (DOPA decarboxylase), into the neurotransmitter, norepinephrine
[4-(2-amino-1-hydroxyethyl)-1,2-benzenediol], by removal of the single
carboxylic acid group of L-serine.