 Initially, Promin appeared to be safer than dapsone, so it was further investigated at the Mayo Clinic as a treatment for tuberculosis in a guinea pig model.Because it was already known that leprosy and tuberculosis were both caused by mycobacteria ("Mycobacterium leprae" and "Mycobacterium tuberculosis", respectively), Guy Henry Faget of the National Leprosarium in Carville, Louisiana, requested information about the drug from Parke-Davis.They, in turn, informed him of the work being done on leprosy in rats by Edmund Cowdry at the Washington University School of Medicine.