1引言药物必须通过吸收,利用血循环到达它的作用部位后才有可能结合受体发挥药理作用。常用的给药方法有口服给药和注射给药。消化道有广阔的吸收表面,血流丰富,有利于药物的吸收,但药物进入体循环以前,部分药物经肝脏降解,令到达体循环的药量减少,被称为首过效应。因此,口服药 1 Introduction The drug must be able to bind to the receptor to exert its pharmacological effects after absorption and utilization of the blood circulation to reach its site of action. Commonly used methods of administration are oral administration and injection administration. The digestive tract has a broad absorption surface, rich blood flow, is conducive to the absorption of drugs, but before the drug into the systemic circulation, part of the drug degradation by the liver, so that the dose to reach the systemic circulation, known as the first pass effect. Therefore, oral medication