title: The controversy concerning plasma homocysteine in Parkinson disease patients treated with levodopa alone or with entacapone: effects of vitamin status.
abstract: Levodopa treatment of Parkinson disease results in hyperhomocysteinemia (HHcy) as a consequence of levodopa methylation by catechol-O-methyltransferase (COMT). Although inhibition of COMT should theoretically prevent or reduce levodopa-induced HHcy, results from several prospective studies are conflicting. Our review of these studies suggests that the ability of COMT inhibition to reduce or prevent levodopa-induced HHcy in Parkinson disease patients may be attributed to differences in the vitamin status of the study participants. In patients with low or low-normal folate levels, levodopa administration is associated with a greater increase in homocysteine and concomitant entacapone administration is associated with a greater reduction in homocysteine.
authors.affiliation: Parkinson's Disease and Movement Disorders Center, University of South Florida, Tampa, 33612, USA. tzesiewi@hsc.usf.edu
authors.forename: Theresa A
authors.initials: TA
authors.lastname: Zesiewicz
authors.forename: Lynn
authors.initials: L
authors.lastname: Wecker
authors.forename: Kelly L
authors.initials: KL
authors.lastname: Sullivan
authors.forename: Lisa R
authors.initials: LR
authors.lastname: Merlin
authors.forename: Robert A
authors.initials: RA
authors.lastname: Hauser
mesh_terms: D002394:Catechol O-Methyltransferase / Q000097:blood; D065098:Catechol O-Methyltransferase Inhibitors; D002396:Catechols / Q000627:therapeutic use*; D004359:Drug Therapy, Combination; D005492:Folic Acid / Q000097:blood; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D007980:Levodopa / Q000009:adverse effects / Q000627:therapeutic use*; D009570:Nitriles; D010300:Parkinson Disease / Q000097:blood* / Q000188:drug therapy; D016032:Randomized Controlled Trials as Topic; D014805:Vitamin B 12 / Q000097:blood; D014815:Vitamins / Q000097:blood*
chemical_list: D065098:Catechol O-Methyltransferase Inhibitors; D002396:Catechols; D009570:Nitriles; D014815:Vitamins; D006710:Homocysteine; D007980:Levodopa; C071192:entacapone; D005492:Folic Acid; D002394:Catechol O-Methyltransferase; D014805:Vitamin B 12