Possible Interaction: Dopamine and Vitamin B 6

“The blocking of the systemic uptake of dopamine has eliminated the previous complications of nausea, vomiting, and cardiac and respiratory arrhythmias; pyridoxine need not now be avoided.”

“Analysis of the 330-nm absorbing species on HPLC and spectrophotometry showed that it is a 1:1 adduct of PLP and dopamine , probably the Pictet-Spengler type adduct formed from the PLP-dopamine Schiff base.”

“Administration of each component at doses equimolar to 1 mg metadoxine showed that pyridoxine produced only a mild increase in striatal dopamine compared with controls.”

“ Dopamine administration led to an average fall of 20% (p = 0.04) in plasma pyridoxal 5'-phosphate (PLP) levels, which declined 42% by day 5.”

“ Dopamine with pyridoxine caused a PLP rise of 65% (p = 0.007), but the post-study level was 28% lower than baseline (p = 0.04).”

“We interpret our data to mean that dopamine reduced PLP levels during and 3 days after the study, and that dopamine appeared to increase the requirements for B6.”

“Administration of either Levodopa (l‐DOPA) or pyridoxine increased the concentration of dopamine in the basal ganglia of rats.”

“However, nonenzymatio studies under conditions similar to those of the … reveal that most of the inhibition by dopa, dopamine and norepinephrine is due to … of these compounds with pyridoxal phosphate while reaction between pyridoxal phosphate and the tryptophan derivatives, 5-… and serotonin, does not occur under the conditions employed.”