Lindén I B, Niemi S
Acta Pharmacol Toxicol (Copenh). 1982 Nov;51(5):434-40. doi: 10.1111/j.1600-0773.1982.tb01049.x.
The effect of 3,4-dihydroxyphenylpyruvic acid (DHPPA) on the hepatic metabolism of L-DOPA was investigated in isolated perfused rat liver. DHPPA decreased the initial hepatic extraction and prolonged the elimination half-life of L-DOPA when they were added simultaneously at the ratio 1:4 (L-DOPA: DHPPA) to the perfusate. At the ratio 1:1 DHPPA had no effect on the elimination half-life, but decreased the initial hepatic extraction of L-DOPA. When L-DOPA was added alone the initial loss of L-DOPA was 30% at 5 min. At that time the perfusion medium had passed the liver 2.5 times. Between 5 to 60 min. about 5% of the dose was extracted in a single pass through the liver. DHPPA added alone or together with L-DOPA was rapidly converted to L-DOPA, only about half of the DHPPA dose remained unmetabolized in the "plasma" at 2.5 min. The main metabolites in bile of all the compounds tested were conjugates of homovanillinic acid and 3,4-dihydroxyphenylacetic acid.
在离体灌注大鼠肝脏中研究了3,4-二羟基苯丙酮酸（DHPPA）对左旋多巴肝脏代谢的影响。当以1:4（左旋多巴：DHPPA）的比例同时添加到灌注液中时，DHPPA降低了肝脏对左旋多巴的初始摄取，并延长了左旋多巴的消除半衰期。在1:1的比例下，DHPPA对消除半衰期没有影响，但降低了肝脏对左旋多巴的初始摄取。当单独添加左旋多巴时，5分钟时左旋多巴的初始损失为30%。此时灌注介质已通过肝脏2.5次。在5至60分钟之间，单次通过肝脏约5%的剂量被摄取。单独添加或与左旋多巴一起添加的DHPPA迅速转化为左旋多巴，在2.5分钟时，“血浆”中只有约一半的DHPPA剂量未被代谢。所有测试化合物在胆汁中的主要代谢产物是高香草酸和3,4-二羟基苯乙酸的缀合物。
