title: Effects of tolcapone, a catechol-O-methyltransferase inhibitor, on motor symptoms and pharmacokinetics of levodopa in patients with Parkinson's disease.
abstract: The effects of tolcapone, a catechol-O-methyltransferase inhibitor, on the bioavailability and efficacy of levodopa were evaluated in 12 patients with Parkinson's disease (PD), 8 of whom showed signs of daily motor fluctuations (wearing-off phenomenon). Motor disabilities were assessed in 12 patients at 7 time points before and after the chronic administration of tolcapone using the Unified Parkinson's Disease Rating Scale (UPDRS). The UPDRS score was improved at all points of determination. Eight patients with wearing-off phenomenon on levodopa showed symptomatic improvement on the combination. The area under the curve (AUC) for levodopa increased by 34% (p = 0.0059) after the administration of tolcapone. The elimination half-life (T1/2) of levodopa was significantly prolonged by 81% (p = 0.0001) after the treatment. The AUC of 3-O-methyldopa, a metabolite of levodopa, was decreased by 79% (p = 0.0001) and the Cmax (maximum concentration) was also decreased by 80%d after the administration (p = 0.0001) of tolcapone. The combination of tolcapone and levodopa was well tolerated. Our findings suggest that tolcapone improves the pharmacokinetics of levodopa in plasma and motor symptoms of fluctuating PD patients. It is suggested that tolcapone may be useful drug adjunct to levodopa in treating patients with PD with wearing-off phenomena.
authors.affiliation: Department of Neurology, Kagawa Prefectural Central Hospital, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yamamoto
authors.forename: M
authors.initials: M
authors.lastname: Yokochi
authors.forename: S
authors.initials: S
authors.lastname: Kuno
authors.forename: Y
authors.initials: Y
authors.lastname: Hattori
authors.forename: Y
authors.initials: Y
authors.lastname: Tsukamoto
authors.forename: H
authors.initials: H
authors.lastname: Narabayashi
authors.forename: H
authors.initials: H
authors.lastname: Tohgi
authors.forename: Y
authors.initials: Y
authors.lastname: Mizuno
authors.forename: H
authors.initials: H
authors.lastname: Kowa
authors.forename: N
authors.initials: N
authors.lastname: Yanagisawa
authors.forename: I
authors.initials: I
authors.lastname: Kanazawa
mesh_terms: D000368:Aged; D000978:Antiparkinson Agents / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D019540:Area Under Curve; D001577:Benzophenones / Q000627:therapeutic use*; D065098:Catechol O-Methyltransferase Inhibitors; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D005260:Female; D006207:Half-Life; D006801:Humans; D007980:Levodopa / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009596:Nitrophenols; D010300:Parkinson Disease / Q000188:drug therapy* / Q000378:metabolism* / Q000503:physiopathology; D000077867:Tolcapone; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D000978:Antiparkinson Agents; D001577:Benzophenones; D065098:Catechol O-Methyltransferase Inhibitors; D004791:Enzyme Inhibitors; D009596:Nitrophenols; D014443:Tyrosine; D007980:Levodopa; D000077867:Tolcapone; C008404:3-methoxytyrosine