代谢
一项由6名健康男性志愿者参与的质量平衡临床试验显示,服用西替利嗪后,70%的放射性剂量在尿液中测量到,10%在粪便中测量到。大约50%的放射性剂量以未改变的西替利嗪形式在尿液中测量到。血浆中放射性峰值快速增加的大部分与母药有关,这意味着首次通过肝脏的代谢水平较低。这阻止了西替利嗪与与肝细胞色素酶相互作用的药物发生潜在的相互作用。西替利嗪部分通过氧化O-脱烷基化代谢为一种不具有显著抗组胺活性的代谢物。负责西替利嗪这一代谢步骤的酶或酶尚未被鉴定。
A mass balance clinical trial comprised of 6 healthy male study volunteers showed that 70% of the administered radioactivity was measured in the urine and 10% in the feces after cetirizine administration. About 50% of the radioactivity was measured in the urine as unchanged cetirizine. Most of the rapid increase in peak plasma radioactivity was related to the parent drug, implying a low level of first pass metabolism. This prevents potential interactions of cetirizine with drugs interacting with hepatic cytochrome enzymes. Cetirizine is metabolized partially by oxidative O-dealkylation to a metabolite with insignificant antihistaminic activity. The enzyme or enzymes responsible for this step in cetirizine metabolism have not yet been identified.
来源:DrugBank