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(1/2alpha)) and elimination half-life (t(1/2beta)) were 0.36 +/- 0.07 h and 7.42 +/- 3.55 h, respectively. The volume of distribution of NFLXGA at steady state (Vd(ss)) was 4.66 +/- 1.39 l/kg. After p.o. administration of NFLXGA, the maximal absorption concentration (C(max)) was 0.43 +/- 0.06 microg/ ml at 1.36 +/- 0.39 h (T(max)). The mean absorption (t(1/2ka)) and elimination half-life (t(1/2beta)) of NFLXGA were 0.78 +/- 0.27 h and 7.13 +/- 1.41 h, respectively. The mean systemic bioavailability (F) after p.o. administration was 31.10 +/- 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.