03.01.5.1 Introduction

Another target at which drugs can bind as the first step in pharmacodynamics is carriers, such as transporters and pumps. A transporter is like a bus, the endogenous compound hops on at one site (A) and is transported across a membrane to another site (B), where it hops off (Figure 3.13). Transporters are involved in both pharmacokinetics and pharmacodynamics. Thus, in drug absorption, transporters are used to transport certain drugs across the membrane. Thus, if Drug C has a similar structure to the endogenous compound, it may be transported across the membrane. With pharmacodynamics, we often use drugs to inhibit the transport of endogenous compound. Thus, Drug D binds to the transporter, but is not transported. However, by binding to the transporter, Drug D prevents the endogenous compound from being transported.

Figure 3.13 Drugs and transporters (Copyright QUT University, Sheila Doggrell)