Difloxacin hydrochloride CAS No. 91296-86-5 Formula C21H19F2N3O3 · HCl Molecular weight of 435.85 Characters : odorless, bitter taste. Use : difloxacin is quinolone antibiotic commonly used veterinary drugs. This is a potential treatment for Chlamydia trachomatis infection and human chronic Q fever. It has been used to study the supplement (magnesium) horse and dog models how to reduce the damage caused by quinolones.