Fig. 1. Potential sources of chiral contributions to anesthetic drug actions in vivo . Differences caused by pharmacokinetic as well as pharmacodynamic interactions may influence the disposition of drugs throughout the body and their actions at their target tissues or receptors. Absent from this diagram is that the main action of a drug may influence its own disposition; for example, an agent that acts peripherally on the sympathetic nervous system may alter local blood flow and thus modify its own vascular removal.