Human Pharmacokinetics and Safety Profile of Finafloxacin, a New Fluoroquinolone Antibiotic, in Healthy Volunteers†

Finafloxacin is a new fluoroquinolone antibiotic with the unique property of increasing antibacterial activity at pH values lower than neutral. Whereas its antibacterial activity at neutral pH matches that of other quinolones in clinical use, it is expected to surpass this activity in tissues and body fluids acidified by the infection or inflammation processes. Pharmacokinetic parameters of oral single and multiple doses of up to 800 mg of finafloxacin and safety/tolerability observations were assessed in a phase I study including 95 healthy volunteers. Finafloxacin is well absorbed after oral administration, generating maximum concentrations (Cmaxs) in plasma at least comparable to those of other fluoroquinolones, with a half-life of around 10 h. About one-third of the dose is excreted unchanged in the urine. Renal elimination appears to be a saturable process leading to slight increases of the area under the concentration-time curve extrapolated to infinity and dose normalized (AUC,norm) at dosages of 400 mg and above. Safety and tolerability data characterize finafloxacin as a drug with a favorable safety profile. In particular, adverse reactions regarded as class-typical of fluoro-quinolones, such as, e.g., electrocardiogram (ECG) changes, neurotoxic effects, or hypoglycemia, were not observed in the study population. Fluoroquinolones in clinical use constitute a class of antibi-otics that are both effective and, in general, rather well toler