Pharmacokinetics II: Multiple Intravenous Injections

Abstract

If a drug that is eliminated exponentially from the plasma is administered intravenously in repeated doses of amount I, at time intervals equal to t′ the plasma concentration-time relation will be as shown in Figure 27.1. We have denoted by V the apparent volume of distribution and by C the plasma concentration of the drug. After time t′, but before the second dose I is given, the concentration falls to some fraction f of the original concentration. (It is assumed that the drug distributes rapidly.) The fraction f is related to the elimination rate constant k_e according to

$$f = {e^{ - {k_e}t'}}.$$

((27.1))