entacapone and nebicapone

To determine the efficacy, safety and tolerability of nebicapone, a new catechol-O-methyltransferase inhibitor for the treatment of motor fluctuations in Parkinson's disease (PD), we conducted a multicenter, randomized, 8-week double-blind, placebo- and active-controlled, parallel-group study comparing nebicapone 50 mg, 100 mg, or 150 mg, entacapone 200 mg (active control) or placebo administered concomitantly with levodopa/carbidopa or levodopa/benserazide. Two hundred and fifty-two PD patients with motor fluctuations treated with levodopa/carbidopa or levodopa/benserazide (4-8 daily doses) were enrolled and 250 patients were eligible for intention-to-treat (ITT) analysis on the basis of having at least one efficacy assessment. The primary endpoint was 8-week change from baseline in absolute "Off" time duration noted in self-scoring diaries. At 8 weeks of treatment the mean daily "Off" time decreased significantly compared to placebo for nebicapone 150 mg (-106 min; 95%CI: -192; -21) and entacapone 200 mg (-81 min; 95%CI: -142; -19). The decrease in "Off" time with nebicapone 50 mg or 100 mg did not reach statistical significance. Treatment-emergent adverse events were reported by 32% to 49% of patients in any treatment group, with no observed dose relationship in the nebicapone groups. Clinically relevant elevations in aspartate transaminase (AST) and/or alanine transaminase (ALT) were observed in 4 of 46 patients with the nebicapone 150 mg dose. The results of this study show that nebicapone 150 mg is efficacious for the treatment of motor fluctuations in PD patients. However, the risk of increasing liver transaminases and its clinically relevance deserves further evaluation.

Topics: Acetophenones; Adult; Aged; Aged, 80 and over; Antiparkinson Agents; Benserazide; Carbidopa; Catechol O-Methyltransferase Inhibitors; Catechols; Double-Blind Method; Endpoint Determination; Enzyme Inhibitors; Female; Humans; Levodopa; Male; Middle Aged; Nitriles; Parkinson Disease; Treatment Outcome

Catechol O-methyltransferase (COMT) is the enzyme responsible for the O-methylation of endogenous neurotransmitters and of xenobiotic substances and hormones incorporating catecholic structures. COMT is a druggable biological target for the treatment of various central and peripheral nervous system disorders, including Parkinson's disease, depression, schizophrenia, and other dopamine deficiency-related diseases. The purpose of this perspective is fourfold: (i) to summarize the physiological role of COMT inhibitors in central and peripheral nervous system disorders; (ii) to provide the history and perspective of the medicinal chemistry behind the discovery and development of COMT inhibitors; (iii) to discuss how the physicochemical properties of recognized COMT inhibitors are understood to exert influence over their pharmacological properties; and (iv) to evaluate the clinical benefits of the most relevant COMT inhibitors.

Topics: Acetophenones; Animals; Catalysis; Catechol O-Methyltransferase; Catechol O-Methyltransferase Inhibitors; Catechols; Clinical Trials as Topic; Crystallography, X-Ray; Humans; Inhibitory Concentration 50; Levodopa; Male; Models, Molecular; Nitriles; Oxadiazoles; Parkinson Disease; Prodrugs; Rats

A homologous series of novel nitro-catechol structures (7a-7e) were synthesized and tested as inhibitors of the enzyme catechol-O-methyltransferase (COMT). Increasing chain length was found to have significant impact on both brain penetration and duration of COMT inhibition in the rat. Of this series, compound 7b (1-(3,4-dihydroxy-5-nitrophenyl)-2-phenyl-ethanone) was found to exhibit the most potent and selective inhibition of peripheral COMT, with an inhibition profile more similar to entacapone 2 than tolcapone 1 (an equipotent peripheral and central inhibitor) but with much improved duration of action (7b, 70% inhibition and 2, 25% inhibition at 9 h after administration). The effects of structural modifications to 7b on COMT inhibitory profile were investigated, and it is concluded that the carbonyl group and preferably unsubstituted aromatic ring are essential features to maintain prolonged peripheral COMT inhibition. The introduction of the alpha-methylene group, the major structural difference between 7b and 1, would appear responsible for the observed enhancement in selectivity of peripheral COMT inhibition of 7b, which has more limited access to the brain than 1.

Topics: Acetophenones; Animals; Brain; Catechol O-Methyltransferase; Catechol O-Methyltransferase Inhibitors; Enzyme Inhibitors; Humans; In Vitro Techniques; Liver; Male; Rats; Rats, Wistar; Structure-Activity Relationship; Tumor Cells, Cultured