The pharmacokinetics and dosage regimen of norfloxacin- glycine acetate (NFLXGA) was investigated in pigs after a single intravenous (i.v.) or oral (p.o.) administration at a dosage of 7.2 mg/kg body weight. After both i.v. and p.o. administration, plasma drug concentrations were best fitted to an open two-compartment model with a rapid distribution phase. After i.v. administration of NFLXGA, the distribution (t_1/2¥á) and elimination half-life (t_1/2¥â) were 0.36 ¡¾ 0.07 h and 7.42 ¡¾ 3.55 h, respectively. The volume of distribution of NFLXGA at steady state (Vd_ss) was 4.66 ¡¾ 1.39 l/kg. After p.o. administration of NFLXGA, the maximal absorption concentration (C_max) was 0.43 ¡¾ 0.06 ¥ìg/ ml at 1.36 ¡¾ 0.39 h (Tmax). The mean absorption (t_1/2ka) and elimination half-life (t_1/2¥â) of NFLXGA were 0.78 ¡¾ 0.27 h and 7.13 ¡¾ 1.41 h, respectively. The mean systemic bioavailability (F) after p.o. administration was 31.10 ¡¾ 15.16%. We suggest that the optimal dosage calculated from the pharmacokinetic parameters is 5.01 mg/kg per day i.v. or 16.12 mg/kg per day p.o.