生物半衰期是指药物在体内消除一半所需要的时间,常以血浆中药物浓度下降一半所需要的时间来表示,故亦称血浆半衰期,它反映了药物在体内的消除速度。每个药物都有各自的半衰期,因此按常规每日三次的给药方案并不适合所有的药物,更不适合每个病人。合理用药在临床治疗中是非常重要的,目前制订合理的给药方案时常采用两种方法:一种是直接通过测定病人的血药浓度,求得病人的药代动力学参数,然后计算制订给药方案。此方案正确可靠,符合病人的具体要求,但需要有测定血药浓度的条件,目 Half-life refers to the half-life of drugs in the body to eliminate half of the time required, often in plasma concentrations of drugs half the time required to represent, it is also known as plasma half-life, which reflects the drug elimination rate in the body. Each drug has its own half-life, so routine dosing schedules three times a day are not suitable for all drugs, but not for each patient. Rational drug use is very important in clinical treatment. At present, two methods are often used to formulate a rational drug delivery plan: one is to determine the patient’s pharmacokinetic parameters directly by measuring the patient’s plasma concentration, and then calculate the formula Drug program. This program is correct and reliable, in line with the specific requirements of patients, but the need for determination of plasma concentrations of conditions, head