Antimicrobial safety and tolerability: differences and dilemmas.

The adverse drug reactions associated with antimicrobials have become a topic of major importance and concern in the last few years. Antimicrobial toxicity may take many forms, varying from mild, transient phenomena to dramatic, life-threatening events such as seizures or cardiac arrhythmias. We review the toxicity of antimicrobials in general and of the fluoroquinolones in particular and attempt to explain the adverse events by use of structure-adverse event relationships where possible. There are currently 5 main mechanisms that can be invoked to explain antimicrobial toxicity: direct effects, hypersensitivity, changes in microbial flora, drug interactions, and microbial lysis. The adverse drug reactions seen with fluoroquinolones are explained on the basis of these 5 mechanisms. The various organ systems affected by the fluoroquinolones are considered; then individual members of the fluoroquinolone class are reviewed. The unexpected and dramatic problems encountered with temafloxacin and trovafloxacin are discussed as well.