Disposition of metronidazole in hens<i>(Gallus gallus)</i>and quails<i>(Coturnix coturnix japonica)</i>: pharmacokinetics and whole‐body autoradiography

Abstract

Hens were given single intravenous or oral doses (30 mg/kg body weight) of metronidazole and the plasma concentrations of the drug were determined by high-performance liquid chromatography (HPLC) at intervals from 10 min to 24 h after drug administration. Pharmacokinetic variables were calculated by the Lagrange algorithm technique. The elimination half-life (t1/2 beta) after the intravenous injection was 4.2 +/- 0.5 h, the volume of distribution (Vd(ss) 1.1 +/- 0.2 L/kg and the total body clearance (ClB) 131.2 +/- 20 mL/h.kg. Oral bioavailability of the metronidazole was 78 +/- 16%. The plasma maximum concentration (Cmax) 31.9 +/- 2.3 micrograms/mL was reached 2 h after the oral administration and the oral elimination half-life (t1/2 beta) was 4.7 +/- 0.2 h. The binding of metronidazole to proteins in hen plasma was very low (less than 3%). Whole body autoradiography of [3H] metronidazole in hens and quails showed an even distribution of labelled material in various tissues at short survival intervals (1-4 h) after oral or intravenous administration. A high labelling was seen in the contents of the small and large intestines. In the laying quails a labelling was also seen in the albumen and in a ring in the periphery of the yolk at long survival intervals. Our results show that a concentration twofold above the MIC is maintained in the plasma of hens for at least 12 h at an oral dose of 30 mg/kg metronidazole.