Systemic and brain bioavailabilities of d-Phenylglycine-l-Dopa, a sustained dopamine-releasing prodrug

d -Phenylglycine- l -Dopa ( d -PhG- l -Dopa), designed as a dipeptide mimetic prodrug of dopamine, has been proven to have 31-fold higher oral bioavailability than l -Dopa in rats. To further investigate if this dipeptide enters the brain, a single-dose pharmacokinetic study by i.v. administration, in comparison with l -Dopa, was conducted to monitor brain availability. The dopamine level in the brain was also determined. The results indicated...