Plasma concentration of local anaesthetic agents in regard to absorption, distribution and elimination, with special reference to bupivacaine.

Absorption from the injection site, tissue distribution, metabolism and urinary excretion are the factors determining the plasma concentration of local anaesthetic agents. Other factors such as physico-chemical properties of these drugs may have important influences on these processes. An example of this is the difference in tissue distribution and plasma/erythrocyte ratio as well as an increase in plasma concentration of bupivacaine seen in acidosis. The importance for the plasma concentration, of protein binding, vasoactivity and the effect of depressed circulation are discussed.