A method of treating an anthrax infection wherein a compound of formula I [chemical expression included] wherein R1 and R2 represent, independently of one another unsubstituted or specifically substituted C1-4alkoxy; and R3 represents hydrogen; cyano; unsubstituted or specifically substituted C1-6alkyl; C3-6cycloalkyl; C2-6alkenyl; C7-18bicyclyl; aryl, aryl-C1-4alkyl, aryl-Q-C1-4alkyl heteroaryl, heterocyclyl or heterocyclyl-C1-6alkyl, wherein aryl denotes a mono- or poly-nucleous group with 6 to 14 ring carbon atoms; heterocyclyl denotes a 4- to 6-membered non-aromatic heterocyclic group comprising 1 to 3, nitrogen, oxygen and/or sulfur atoms; heteroaryl denotes a mono- or polynuclear heteroaromatic group consisting 5- and/or 6-membered rings and comprising 5 to 13 carbon atoms and 1 to 4, nitrogen, oxygen and/or sulfur atoms; and Q means —SO— or —SO2—; or a pharmaceutically acceptable salt, solvate or hydrate or a prodrug thereof; is administered to said subject in a quantity effective to inhibit, suppress, or expel an anthrax infection in said subject.