Tegnér K, Nilsson H T, Persson C G, Persson K, Ryrfeldt A
Eur J Respir Dis Suppl. 1984;134:93-100.
The main elimination pathways of tritium-labelled terbutaline have been investigated in the rat, the dog, and man. In the rat, 25% of an intravenous dose is excreted unchanged in the urine. Terbutaline is extensively metabolized to the glucuronic acid conjugate which is eliminated via bile (40% of the dose) and urine (25% of the dose). After oral administration, a high first-pass metabolism (70%) was found. In contrast, in the dog, more than 90% of a parenteral dose is excreted renally, largely as unchanged terbutaline together with a small amount of the sulphate conjugate. Only 1.7% of the dose is excreted via bile. The first-pass metabolism amounted to 13%. The elimination of terbutaline in man exhibits a pattern intermediate between rat and dog. Thus, more than 90% of a parenteral dose is eliminated in the urine, of which about 2/3 is unchanged drug. The main metabolite is the sulphate conjugate which is excreted renally. Less than 1% of the dose is excreted in the bile. A large first-pass metabolism (69%) was confirmed in man.
已在大鼠、犬和人体中研究了氚标记特布他林的主要消除途径。在大鼠中，静脉注射剂量的25%以原形经尿液排泄。特布他林广泛代谢为葡萄糖醛酸结合物，经胆汁（剂量的40%）和尿液（剂量的25%）消除。口服给药后，发现首过代谢率较高（70%）。相比之下，在犬中，超过90%的胃肠外给药剂量经肾脏排泄，主要是原形特布他林以及少量硫酸盐结合物。仅1.7%的剂量经胆汁排泄。首过代谢率为13%。人体中特布他林的消除模式介于大鼠和犬之间。因此，超过90%的胃肠外给药剂量经尿液消除，其中约2/3为原形药物。主要代谢物是经肾脏排泄的硫酸盐结合物。剂量的不到1%经胆汁排泄。人体中证实存在较高的首过代谢率（69%）。
