Shibata K
Department of Food Science and Nutrition, Teikoku Women's University, Osaka, Japan.
J Nutr. 1989 Jun;119(6):892-5. doi: 10.1093/jn/119.6.892.
Rats administered excess nicotinamide and nicotinic acid were studied to determine the metabolic fate of pharmacological levels of these compounds. When a large amount of nicotinamide (500 mg/kg body wt) was intraperitoneally injected into rats, 32% of the dose was excreted as nicotinamide, 11% as N1-methylnicotinamide (MNA), 10% as nicotinuric acid, 5% as nicotinic acid, 3% as N1-methyl-4-pyridone-3-carboxamide (4-pyr) and 2% as N1-methyl-2-pyridone-5-carboxamide (2-pyr) during d 1 after the injection. Urinary excretion of these compounds gradually decreased with time and returned to normal by d 3. Urinary excretion of nicotinic acid and nicotinuric acid was observed only on d 1. When a large amount of nicotinic acid (500 mg/kg body wt) was intraperitoneally injected into rats, 55% of the dose was excreted as nicotinic acid and 15% as nicotinuric acid during d 1, and no excretion of these compounds was observed thereafter. The increase in excretion of nicotinamide, MNA, 2-pyr and 4-pyr was slight even on d 1. Excretion of nicotinic acid, nicotinuric acid, nicotinamide, MNA, 2-pyr and 4-pyr returned to normal levels on d 2. From these results, the different fates of excess nicotinamide and nicotinic acid are discussed.
对给予过量烟酰胺和烟酸的大鼠进行了研究，以确定这些化合物药理水平的代谢归宿。当向大鼠腹腔注射大量烟酰胺（500毫克/千克体重）时，注射后第1天，32%的剂量以烟酰胺形式排泄，11%以N1-甲基烟酰胺（MNA）形式排泄，10%以烟尿酸形式排泄，5%以烟酸形式排泄，3%以N1-甲基-4-吡啶酮-3-甲酰胺（4-吡啶）形式排泄，2%以N1-甲基-2-吡啶酮-5-甲酰胺（2-吡啶）形式排泄。这些化合物的尿排泄量随时间逐渐减少，到第3天恢复正常。仅在第1天观察到烟酸和烟尿酸的尿排泄。当向大鼠腹腔注射大量烟酸（500毫克/千克体重）时，第1天55%的剂量以烟酸形式排泄，15%以烟尿酸形式排泄，此后未观察到这些化合物的排泄。即使在第1天，烟酰胺、MNA、2-吡啶和4-吡啶的排泄增加也很轻微。烟酸、烟尿酸、烟酰胺、MNA、2-吡啶和4-吡啶的排泄在第2天恢复到正常水平。根据这些结果，讨论了过量烟酰胺和烟酸的不同归宿。
