Comparison of fluoroquinolone pharmacokinetic parameters after treatment with marbofloxacin, enrofloxacin, and difloxacin in dogs

Plasma, urine, and skin drug concentrations were determined for dogs (n = 12) given five daily oral doses of marbofloxacin (MAR) (2.75 mg/kg), enrofloxacin (ENR) (5.0 mg/kg) or difloxacin (DIF) (5.0 mg/kg), Concentrations of the active metabolite of ENR, ciprofloxacin (CIP), were also determined. The three-period, three-treatment crossover experimental design included a 21-day washout period between treatments. Area under the plasma drug concentration vs, time curve (AUC(O-last), mug/mL x h of MAR was greater than for ENR, CIP, ENR/CIP combined, and DIP, Maximum concentration (C-max) of MAR was greater than ENR, CIP, and DIF. Time of maximum plasma concentration (T-max) was similar for MAR and DIF; T-max occurred earlier for ENR and later for CIP. Plasma half-life (t(1/2)) of MAR was longer than for ENR, CIP, and DIF. Urine concentrations of DIF were less than MAR or ENR/CIP combined, but urine concentrations of MAR and ENR/CIP combined did not differ. DIF skin concentrations were less than the concentrations of MAR or ENR/CIP combined 2 h after dosing, but skin concentrations of MAR and ENR/CIP combined did not differ.