Fleroxacin (Ro 23-6240, AM 833) is different from fluoroquinolones such as ciprofloxacin or ofloxacin, since it is a trifluorinated quinolone, having three fluorine atoms rather than one attached to the quinolone ring system. It is a 6,8-difluoro-1-(2-fluorethyl)-1,4-dihydro-7- (4-methyl-1-piperazinyl)-4-oxo-3-quinolonine carboxylic acid. A major advantage of fleroxacin is its long half-life, allowing once-daily dosing. However, the extra fluorine atoms have led to a higher rate of dose-related adverse side-effects than other fluoroquinolones, leading to the withdrawal of the drug in some countries.

Uses

Fleroxacin has been used in a variety of clinical conditions, but there have been few studies in recent years owing to the availability of other fluoroquinolones with improved toxicity profiles. Nevertheless, for regions where fleroxacin remains available and adverse reactions can be readily monitored, fleroxacin has activity in a number of conditions.

Bioavailability 

Oral absorption is 95–100% in healthy volunteers, substantially better than that of many other early fluoroquinolones. Owing to this excellent bioavailability, serum fleroxacin concentrations are nearly identical for oral and i.v. doses. Fleroxacin is 32% protein bound. The oral bioavailability of fleroxacin is not substantially affected by the intake of a light meal, or a fat- or calcium-rich breakfast. Although co-administration of calcium-containing antacids does not alter fleroxacin bioavailability, aluminum- and magnesium-containing antacids and sucralfate result in approximately a 25% reduction in maximum serum fleroxacin concentrations and AUC – less than for other fluoroquinolones.

Toxicity   

Fleroxacin was withdrawn from the market in Europe by Roche in the late 1990s due to two significant dose-related adverse events: phototoxicity and central nervous system toxicity. These adverse events were noted in premarketing trials, but increasing reports in the postmarketing period led to withdrawal of the drug in Europe.