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Pharmacokinetics and bioavailability of doxycycline in fasted and nonfasted broiler chickens

Laczay, P., Semjén, G., Lehel, J., Nagy, G.
Acta veterinaria Hungarica 2001 v.49 no.1 pp. 31-37
absorption, bioavailability, body weight, broiler chickens, doxycycline, drug excretion, drugs, half life, intestines, intravenous injection, oral administration, pharmacokinetics
The pharmacokinetics and the influence of food on the kinetic profile and bioavailability of doxycycline was studied after a single intravenous (i.v.) and oral dose of 10.0 mg/kg body weight in 7-week-old broiler chickens. Following i.v. administration the drug was rapidly distributed in the body with a distribution half-life of 0.21 ± 0.01 h. The elimination half-life of 6.78 ± 0.06 h was relatively long and resulted from both a low total body clearance of 0.139 ± 0.007 L/h·kg and a large volume of distribution of 1.36 ± 0.06 L/kg. After oral administration to fasted chickens, the absorption of doxycycline was quite fast and substantial as shown by the absorption half-life of 0.39 ± 0.03 h, the maximal plasma concentration of 4.47 ± 0.16 —g/mL and the time to reach the C ₘₐₓ of 1.73 ± 0.06 h. The distribution and the final elimination of the drug were slower than after i.v. administration. The absolute bioavailability was 73.4 ± 2.5%. The presence of food in the intestinal tract reduced and extended the absorption (t ₁/₂ₐ = 1.23 ± 0.21 h; C ₘₐₓ = 3.07 ± 0.23 µg/mL; t ₘₐₓ = 3.34 ± 0.21 h). The absolute bioavailability was reduced to 61.1% ± 4.4%.