Tang-Liu D D, Riegelman S
Res Commun Chem Pathol Pharmacol. 1981 Dec;34(3):371-80.
Caffeine and its major metabolite, paraxanthine, were observed in plasma following oral administration of theophylline in a multiple dose study. At steady state, plasma caffeine concentrations varied from 0.21 to 0.75 mg/L at plasma theophylline concentrations of 8.1 to 21.5 mg/L in four healthy subjects. About 6% of the theophylline dose was converted to caffeine, which is further metabolized to a series of degradation products, which can be measured after caffeine administration, accounted for the incomplete urinary recovery usually observed after theophylline administration.
在一项多剂量研究中，口服茶碱后在血浆中观察到了咖啡因及其主要代谢物对黄嘌呤。在稳态时，四名健康受试者血浆中茶碱浓度为8.1至21.5mg/L时，血浆咖啡因浓度在0.21至0.75mg/L之间变化。约6%的茶碱剂量转化为咖啡因，咖啡因进一步代谢为一系列降解产物，在给予咖啡因后可进行测量，这解释了通常在给予茶碱后观察到的尿回收率不完全的现象。
