a 77-year-old man with parkinson 's disease of long standing , under treatment with l-dopa and benserazide , was administered dl-threo-3 , 4-dihydroxyphenylserine ( dl-threo-dops ) , a precursor of norepinephrine , for 10 days .
C0030567
parkinson 's disease
C0023570
l-dopa