Physico-Chemical Characterization of Drugs and Drug Forms in the Solid State

This review addresses the general problem of the physico-chemical characterization of drugs and drug products. The characterization may be performed with a range of methods that appears to be mostly limited by imagination, and aims to fulfill one or more of the following goals: gather data relevant in predicting / optimizing performances of a drug, selecting its delivery system, planning a scaled-up production and associated quality controls, complying with regulations. In keeping with the general focus of the Journal, most examples presented will deal with antinfective agents, although the physico-chemical characterization is largely independent of the therapeutic goal. We begin by reviewing the substantial and recent advances in new classes of materials for drug delivery and in techniques for experimental and theoretical studies of physico-chemical properties of pharmaceutical compounds. We then introduce through examples the complex phenomenology of these properties, which may be investigated also with standard and inexpensive experimental techniques. The last part of the review addresses the problem of defining a fast and reliable protocol for investigating drug-excipient compatibility problems.