Pharmacokinetics of norfloxacin after intravenous, intramuscular and subcutaneous administration to rabbits.

The disposition kinetics of norfloxacin, after intravenous, intramuscular and subcutaneous administration was determined in rabbits at a single dose of 10 mg/kg. Six New Zealand white rabbits of both sexes were treated with aqueous solution of norfloxacin (2%). A cross-over design was used in three phases (2 × 2 × 2), with two washout periods of 15 days. Plasma samples were collected up to 72 hr after treatment, snap-frozen at -45°C and analysed for norfloxacin concentrations using high-performance liquid chromatography. The terminal half-life for i.v., i.m. and s.c. routes was 3.18, 4.90 and 4.16 hr, respectively. Clearance value after i.v. dosing was 0.80 L/h·kg. After i.m. administration, the absolute bioavailability was (mean ± SD) 108.25 ± 12.98% and the C _max was 3.68 mg/L. After s.c. administration, the absolute bioavailability was (mean ± SD) 84.08 ± 10.36% and the C _max was 4.28 mg/L. As general adverse reactions were not observed in any rabbit and favourable pharmacokinetics were found, norfloxacin at 10 mg/kg after i.m. and s.c. dose could be effective in rabbits against micro-organisms with MIC ≤0.14 or 0.11 μg/mL, respectively.
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