Hengstmann J H, Goronzy J
Arzneimittelforschung. 1980;30(12):2164-7.
Four volunteers received orally an aqueous solution of 4.5 mg of 14C norfenefrine. Urine was collected for the following 24 h and assayed for unchanged drug and metabolites. Blood was drawn for the determination of free norfenefrine at frequent intervals over an 8-h period. The highest serum levels of free norfenefrine were seen 30-60 min after ingestion with an average of 2 ng/ml. The half-lives ranged from 163-402 min. The cumulative urinary excretion of 14C radioactivity exceeded 90% of the dose, more than 50% being conjugated norfenefrine. As result of the area under the plasma level curve bioavailability has to be set at 20% when compared to other sympathomimetic amines. The result in our patient with porto-caval anastomosis did not differ from normal. Thus, the significance of the gut wall as the site of conjugation during the first-pass is demonstrated.
四名志愿者口服了4.5毫克14C去甲麻黄碱的水溶液。在接下来的24小时内收集尿液，并检测其中未变化的药物和代谢物。在8小时内定期采集血液以测定游离去甲麻黄碱。摄入后30 - 60分钟时观察到游离去甲麻黄碱的血清水平最高，平均为2纳克/毫升。半衰期范围为163 - 402分钟。14C放射性的累积尿排泄量超过剂量的90%，其中超过50%为结合型去甲麻黄碱。与其他拟交感神经胺相比，根据血浆水平曲线下面积，生物利用度设定为20%。我们患有门腔静脉吻合术的患者的结果与正常情况无异。因此，证明了肠壁作为首过效应期间结合部位的重要性。
