in vivo administration of the catechol-protected dopamine coupled with 1,4-dihydrotrigonelline as the carrier resulted in brain-specific , high and sustained concentrations of the 1-methyl-3- [ n- [ beta- ( 3,4-dihydroxyphenyl ) ethyl ] carbamoyl ] pyridinium salt , the direct dopamine precursor , locked in the brain for many hours , while systemic concentration decreased fast , with a t 1/2 of less than 30 min .
C0006104
brain
C0086045
concentration