Fluoroquinolone safety and tolerability

Fluoroquinolones in general have an excellent safety record. Adverse drug reactions primarily affect the gastrointestinal system, skin and CNS, occur at a frequency of around 5% or less and are almost invariably mild in severity. Most are considered class effects. Severe reactions, e.g. phototoxicity, renal syndromes and tendinitis, are rare. Certain fluoroquinolones (FQ) may cause structure-related effects associated with particular side chains, e.g, 8-halogenation and severe phototoxicity, whilst others may produce idiosyncratic reactions which appear to be agent specific. The latter would include the haemolytic-uraemic syndrome associated with temafloxacin and, more recently, the severe and probably immunologically-mediated hepatic reactions observed with trovafloxacin. FQ dec-eloped in the 1990s have conformed to the usual class related effects, although certain agents, e.g. grepafloxacin (GI effects), trovafloxacin (CNS) and the 8-chloro derivatives, clinafloxacin and sitafloxacin (phototoxicity), have higher specific incidences. New phenomena, probably previously unrecognised as class effects, e.g. QTc prolongation and potential for pre-arrhythmic cardiac conduction anomalies, continue to appear. Moxifloxacin has been investigated in almost 5000 patients and, in this population, has been shown to have a low frequency of class-related ADRs and no novel phenomena.