1 Testing a New Drug for Leprosy: Clofazimine and its Precursors in Ireland and Nigeria, 1944-1966 1 John Manton -- University of Oxford In the increasingly laboratory-centred context of mid-twentieth century pharmaceutical research, the persistent difficulties in subjecting leprosy to laboratory investigation presented a paradox, thrusting conceptions of the field, field ethos, and field research conditions centre-stage in assessing the efficacy of chemotherapy in leprosy. Until 1948, with the ratification of Dapsone at the International Leprosy Congress in Havana, there was no universally-recognised effective drug therapy for leprosy, and continued problems in supervising the administration of Dapsone in the following years ran alongside an increasingly active search for alternative drugs. One group of compounds with evident potential for the treatment of leprosy was developed at the laboratories of the Medical Research Council of Ireland (MRCI) on the grounds of Trinity College, Dublin (TCD), through the 1940s and 1950s, leading to the synthesis of B.663, the compound later known as clofazimine. 2 This compound, subject to clinical trials in Nigeria in the early 1960s, is still an effective component of the multi-drug regimen used to treat leprosy today. The development of clofazimine, and the demonstration of its efficacy in treating leprosy, brought together chemists, biologists, clinicians, and medical researchers from locations and institutions in Africa, North America, and Europe over a period of over ten years, building on a complementary set of earlier networks in Irish science and medicine, and articulating a new ethos of field practice and international collaboration