Compositions and methods for administering a therapeutic agent to a mammal are disclosed. The compositions comprise either (i) vesicles comprising an amphiphilic substituted fullerene, wherein the therapeutic agent is present in the vesicle interior or between layers of the vesicle wall, (ii) a substituted fullerene, comprising a fullerene core and a functional moiety, wherein the therapeutic agent is associated with the substituted fullerene, or (iii) carbon nanotubes, wherein the therapeutic agent is covalently bonded to the carbon nanotubes.