左卡尼汀的动力学、药物动力学和监管,乙醯左旋肉碱新陈代谢。

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Rebouche CJ

左卡尼汀的动力学、药物动力学和监管,乙醯左旋肉碱新陈代谢。

安N Y科学。2004年11月,1033:30-41。

PubMed ID

15591001 (在PubMed

]

文摘

在哺乳动物中,肉碱池由nonesterified左卡尼汀和许多acylcarnitine酯。这些酯,乙醯左旋肉碱是定量和功能最重要。肉碱体内平衡是由吸收从饮食,适度的合成、高效的肾脏重吸收。饮食吸收了左卡尼汀主动和被动跨膜肠上皮细胞转移。生物利用度的膳食左卡尼汀54 - 87%,依赖于左卡尼汀在这顿饭的数量。左卡尼汀的吸收膳食补充剂(0.5 6克)主要是被动的;生物利用度是14 - 18%的剂量。未被吸收的左卡尼汀在大肠基本上由微生物降解。循环左卡尼汀分发给两个隔间活动定义:一个大的和slow-turnover肌肉(大概),和另一个相对较小的迅速更新(大概是肝、肾等组织)。在正常饮食左卡尼汀的摄入量,全身周转时间在人类是38 - 119 h。体外实验表明乙醯左旋肉碱部分水解在肠上皮细胞吸收。 In vivo, circulating acetyl-L-carnitine concentration was increased 43% after oral acetyl-L-carnitine supplements of 2 g/day, indicating that acetyl-L-carnitine is absorbed at least partially without hydrolysis. After single-dose intravenous administration (0.5 g), acetyl-L-carnitine is rapidly, but not completely hydrolyzed, and acetyl-L-carnitine and L-carnitine concentrations return to baseline within 12 h. At normal circulating l-carnitine concentrations, renal l-carnitine reabsorption is highly efficient (90-99% of filtered load; clearance, 1-3 mL/min), but displays saturation kinetics. Thus, as circulating L-carnitine concentration increases (as after high-dose intravenous or oral administration of L-carnitine), efficiency of reabsorption decreases and clearance increases, resulting in rapid decline of circulating L-carnitine concentration to baseline. Elimination kinetics for acetyl-L-carnitine are similar to those for L-carnitine. There is evidence for renal tubular secretion of both L-carnitine and acetyl-L-carnitine. Future research should address the correlation of supplement dosage, changes and maintenance of tissue L-carnitine and acetyl-L-carnitine concentrations, and metabolic and functional changes and outcomes.

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药物

Acetylcarnitine