Gillespie W R
Pharmaceutics Division, College of Pharmacy, University of Texas, Austin 78712.
Pharm Res. 1991 Feb;8(2):254-8. doi: 10.1023/a:1015860608173.
The following equations are derived for amount of drug in the body (xbss), volume of distribution (vss), and mean residence time in the body (tb) at steady state during a continuous constant rate infusion of drug. (formula; see text) where c(t) identical to drug concentration in the systemic circulation at time t following the start of a constant-rate infusion, css identical to steady-state systemic drug concentration, and R identical to infusion rate. The equations are based on the assumption that the rate of drug elimination is proportional to the systemic drug concentration. The equations provide the basis for simple methods that are presented for estimating xbss, vss, and tb directly from experimental data. More general relationships are also derived for cases where the continuous infusion is preceded by other modes of administration, e.g., a bolus loading dose followed by a constant-rate infusion.
以下公式是在药物持续恒速输注达到稳态时，针对体内药物量（xbss）、分布容积（vss）和体内平均驻留时间（tb）推导得出的。（公式；见正文）其中c(t)为恒速输注开始后时间t时体循环中的药物浓度，css为稳态体循环药物浓度，R为输注速率。这些公式基于药物消除速率与体循环药物浓度成正比的假设。这些公式为直接从实验数据估算xbss、vss和tb的简单方法提供了基础。对于在持续输注之前还有其他给药方式的情况，例如先给予负荷剂量推注然后进行恒速输注，也推导了更通用的关系。
