actoxumab actoxumab actoxumab is a human monoclonal antibody designed for the prevention of recurrence of clostridium difficile infection. actoxumabmonoclonal antibodytypewhole antibodysourcehumantargetclostridium difficile toxin aclinical dataatc codenoneidentifierscas number1245634-25-6chemspidernoneuniig3lu5lc5sxkeggd10360chemical and physical dataformulac6476h10000n1740o2010s45molar mass145836.11 g·mol−1 this drug, along with bezlotoxumab, was developed through phase ii efficacy trials by a partnership between medarex inc and massbiologics of the university of massachusetts medical school. the project was then licensed to merck & co., inc. for further development and commercialization. a study compared it with bezlotoxumab (that targets cd toxin-b) and found actoxumab less effective.