Abstract
While historians have dealt with the origins of the concept of drug receptors in the work of Paul Ehrlich and John N. Langley as well as with some of its applications in modern pharmaceutical research, the history of the receptor theory as such has been neglected. Discussing major developments and conceptual changes in receptor theory between about 1910 and 1960 , this paper attempts to fill this gap in historiography. It provides a case study of the unfolding of research under a new paradigm, but it considers also contemporary criticism and scepticism. By the early 1960s, quantitative investigations of drug action and interpretations of the experimental findings in terms of the receptor concept had become constitutive of the emerging field of ‘molecular pharmacology’. Even then, however, receptors were still hypothetical entities