vivo, drug-drug, drug­ food and drug-herbals interactions and those that cause drugs to interfere with diagnostic laboratory tests. We believe that an explanation of the mechanisms of such interactions will enable practitioners to understand more fully the nature of the interactions and thus enable them to manage better their clinical outcome. If mechanisms of interactions are better understood, then it may be pos­ sible for the researcher to develop meaningful animal/biochemical/tissue cul­ ture or physicochemical models to which new molecules could be exposed during their development stages. The present position, which largely relies on patients experiencing adverse interactions before they can be established or documented, can hardly be regarded as satisfactory. This present volume is classified into two major parts; firstly, pharmacoki­ netic drug interactions and, secondly, pharmacodynamic drug interactions.