The pharmacokinetics and the influence of food on the kinetic profile and b
ioavailability 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. Fo
llowing i.v. administration the drug was rapidly distributed in the body wi
th a distribution half-life of 0.21 +/- 0.01 h. The elimination half-life o
f 6.78 +/- 0.06 h was relatively long and resulted from both a low total bo
dy clearance of 0.139 +/- 0.007 L/h kg and a large volume of distribution o
f 1.36 +/- 0.06 L/kg. After oral administration to fasted chickens, the abs
orption of doxycycline was quite fast and substantial as shown by the absor
ption half-life of 0.39 +/- 0.03 h, the maximal plasma concentration of 4.4
7 +/- 0.16 mug/mL and the time to reach the C-max of 1.73 +/- 0.06 h. The d
istribution and the final elimination of the drug were slower than after i.
v. administration. The absolute bioavailability was 73.4 +/- 2.5%. The pres
ence 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 mug/mL; t(max) = 3.34 +/- 0
.21 h). The absolute bioavailability was reduced to 61.1% +/- 4.4%.