The pharmacokinetic of norfloxacin (10 mg kg-1) following single
intravenous (IV) and oral administration (PO) in healthy goldfish were
investigated. Also, repeated (PO) administration of norfloxacin in
healthy and experimentally Aeromonas hydrophilia infected goldfish
was studied. Following IV administration, norfloxacin obeyed a two
compartments open model, distribution half-life (t1/2(α)) equal to 0.12
h, volume of distribution (Vdss) was 1.01 L kg-1, elimination halflife
(t1/2(β)) was 4.30 h and total body clearance (CLtot) was 0.17 L
kg-1h-1. Following PO administration, norfloxacin was rapidly and
efficiently absorbed through gastrointestinal tract as the absorption
half-life (t1/2(ab)) was 0.84 h. Maximum serum concentration (Cmax)
4.10 μg ml-1, was achieved its maximum time (tmax) at about 2 h
post administration and the elimination half-life (t1/2(el)) was 3.91 h.
Oral bioavailability was 57.63% indicating moderate absorption
of norfloxacin from oral site. Serum concentrations of norfloxacin
following repeated PO administration of 10 mg kg-1 BW once daily
for 5 consecutive days, were significantly lower in experimentally
Aeromonas hydrophilia infected goldfish than in healthy ones. Based
on these pharmacokinetics parameters determined, a dosage of 10
mg kg-1 BW given orally every 24 h in goldfish can maintain effective
plasma concentrations with Aeromonas hydrophilia infection with
(minimum inhibitory concentration) MIC90 ≤ 0.25 μg ml-1. Therefore,
norfloxacin may be an effective therapy for goldfish diseases.