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1-Methylnicotinamide (MNA), a primary metabolite of nicotinamide, exerts anti-thrombotic activity mediated by a cyclooxygenase-2/prostacyclin pathway.

Chlopicki S, Swies J, Mogielnicki A, Buczko W, Bartus M, Lomnicka M, Adamus J, Gebicki J

1Department of Experimental Pharmacology, Chair of Pharmacology, Jagiellonian University Medical College, Krakow, Poland.

Background and purpose:1-methylnicotinamide (MNA) has been considered to be an inactive metabolite of nicotinamide. Here we assessed the anti-thrombotic activity of MNA in vivo.Experimental approach:Antithrombotic action of MNA was studied in normotensive rats with extracorporeal thrombus formation (thrombolysis), in renovascular hypertensive rats with intraarterial thrombus formation (arterial thrombosis) and in a venous thrombosis model in rats (venous thrombosis).Key results:MNA (3-100 mg kg(-1)) induced a dose-dependent and sustained thrombolytic response, associated with a rise in 6-keto-PGF(1alpha) in blood. Various compounds structurally related to MNA were either inactive or weaker thrombolytics. Rofecoxib (0.01-1 mg kg(-1)), dose-dependently inhibited the thrombolytic response of MNA, indomethacin (5 mg kg(-1)) abolished it, while L-NAME (5 mg kg(-1)) were without effect. MNA (3-30 mg kg(-1)) also reduced arterial thrombosis and this effect was abrogated by indomethacin (2.5 mg kg(-1)) as well as by rofecoxib (1 mg kg(-1)). MNA, however, did not affect venous thrombosis. In vitro MNA did not modify platelet aggregation nor induce vasodilation.Conclusions and implications:MNA displayed a profile of anti-thrombotic activity in vivo that surpasses that of closely related compounds. MNA inhibited platelet-dependent thrombosis by a mechanism involving cyclooxygenase-2 and prostacyclin. Our findings suggest that endogenous MNA, produced in the liver by nicotinamide N-methyltransferase, could be an endogenous activator of prostacyclin production and thus may regulate thrombotic as well as inflammatory processes in the cardiovascular system.British Journal of Pharmacology (2007) 152, 230-239; doi:10.1038/sj.bjp.0707383; published online 16 July 2007.

Published 10 September 2007 in Br J Pharmacol, 152(2): 230-9.
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