Harper P, Elwin C E, Cederblad G
Department of Clinical Chemistry Danderyd Hospital, Sweden.
Eur J Clin Pharmacol. 1988;35(5):555-62. doi: 10.1007/BF00558253.
The pharmacokinetics of single intravenous and oral doses of L-carnitine 2 g and 6 g has been investigated in 6 healthy subjects on a low carnitine diet. Carnitine was more rapidly eliminated from plasma after the higher dose. Comparing the 2-g and 6-g doses, the t1/2 beta of the elimination phase (beta) was 6.5 h vs 3.9 h, the elimination constant was 0.40 vs 0.50 h-1 and the plasma carnitine clearance was 5.4 vs 6.1 1 x h-1 (p less than 0.025), thus showing dose-related elimination. Saturable kinetics was not found in the range of doses given. The apparent volumes of distribution after the two doses were not significantly different and they were of the same order as the total body water. Urinary recoveries after the 2-g and 6-g doses were 70% and 82% during the first 24 h, respectively. Following the two oral dosing, there was no significant difference in AUCs of plasma carnitine. Urinary recoveries were 8% and 4% for the 2-g and 6-g doses during the first 24 h. The oral bioavailability of the 2-g dose was 16% and of the 6 h dose 5%. The results suggest that the mucosal absorption of carnitine is already saturated at the 2-g dose.
在6名采用低肉碱饮食的健康受试者中，研究了单次静脉注射和口服2克及6克左旋肉碱的药代动力学。较高剂量后，肉碱从血浆中消除得更快。比较2克和6克剂量，消除相（β）的t1/2β为6.5小时对3.9小时，消除常数为0.40对0.50 h-1，血浆肉碱清除率为5.4对6.1 1×h-1（p<0.025）, 从而显示出剂量相关的消除。在所给剂量范围内未发现饱和动力学。两次剂量后的表观分布容积无显著差异，且与总体液处于同一量级。2克和6克剂量后，前24小时的尿回收率分别为70%和82%。两次口服给药后，血浆肉碱的AUCs无显著差异。2克和6克剂量在前24小时的尿回收率分别为8%和4%。2克剂量的口服生物利用度为16%，6克剂量为5%。结果表明，2克剂量时肉碱的粘膜吸收已达到饱和。
