Introduction: Evaluating and Standardizing Therapeutic Agents, 1890–1950

It seems evident today that vaccines and other medicines, whether they are intended to be injected, swallowed, or even applied topically, should meet stringent criteria of quality. Indeed, such pharmaceutical products are embedded in specific regulations that have been successively put into place since WWII. The general regulatory consensus is that they should not be unnecessarily harmful,1 and they should contain specified amounts of the active ingredients that a qualified physician has prescribed, combined with only those excipients necessary to facilitate administration and that have also been shown to be innocuous. Furthermore, and this takes us to the heart of the present volume, the dose of the active principle in each unit of consumption — be it pill, phial or suppository — should be fixed and known. The idea behind this requirement is that the effectiveness of the medicine, something one cannot see just by looking at a liquid or a pill, or establish by any simple test, should be precisely known and guaranteed. This, of course, implies that the ‘activity’ of the active principle can be precisely measured in appropriate, well-defined units. Indeed, the pharmaceutical ideal is that the precise physiological effect of the administered product should be predictable and under complete control, an ideal that is, of course, impossible to realize given the variety that exists among human beings (and other living organisms) and their divergent individual responses to both disease and medical treatment.2