title: Pharmacokinetics and bioavailability of doxycycline in turkeys.
abstract: The pharmacokinetic parameters of doxycycline (DOX) were determined in 3 day, 3-, 6- and 12-week-old fasted turkeys, after a single intravenous (i.v.) dose of 25 mg doxycycline. HCl/kg body weight. Doxycycline disposition fitted an open two-compartment model. The mean (+/-SD) elimination half-life was 10.6 +/- 0.7, 10.8 +/- 1.5, 7.9 +/- 1.4 and 10.0 +/- 0.9 h in 3 day, 3-, 6- and 12-week-old turkeys, respectively. Mean (+/- SD) total body clearance was 0.19 (+/-0.01), 0.27 (+/-0.03), 0.11 (+/-0.03) and 0.06 (+/-0.01) L/h.kg in 3 day, 3-, 6- and 12-week-old turkeys, respectively. The steady-state volume of distribution was 1.77 (+/-0.2), 2.1 (+/-0.2), 0.7 (+/-0.4) and 0.5 (+/-0.2) L/kg in turkeys of the above mentioned ages, respectively. The AUC value significantly increased with the age of the turkeys. An oral doxycycline solution at a single dose of 25 mg/kg of body weight was administered to 3 day. 3-, 6- and 12-week-old turkeys. The maximal plasma concentrations in fasted turkeys were 3.8, 5.6, 7.4 and 5.7 micrograms/mL. with tmax values of 4.7, 1.5, 2.8 and 5.4 h, for the different ages, respectively. In fed turkeys the Cmax values were 2.5, 6.1, 4.8 and 3.0 micrograms/mL. with tmax values of 4.2, 5.3, 4.5 and 7.5 h, respectively. The absolute bioavailability in fasted turkeys varied between 25.0 +/- 9.0% (for 12-week-old birds) and 63.5 +/- 7.1% (for 3-week-old birds). The relative bioavailability varied between 40.0 +/- 13.0% (for 12-week-old birds) and 83.7 +/- 14.3% (for 3-week-old birds).
authors.affiliation: Laboratory of Pharmaceutical Technology, Faculty of Pharmacy, University of Gent, Belgium.
authors.forename: M D
authors.initials: MD
authors.lastname: Santos
authors.forename: H
authors.initials: H
authors.lastname: Vermeersch
authors.forename: J P
authors.initials: JP
authors.lastname: Remon
authors.forename: M
authors.initials: M
authors.lastname: Schelkens
authors.forename: P
authors.initials: P
authors.lastname: De Backer
authors.forename: H J
authors.initials: HJ
authors.lastname: Van Bree
authors.forename: R
authors.initials: R
authors.lastname: Ducatelle
authors.forename: F
authors.initials: F
authors.lastname: Haesebrouck
mesh_terms: D000284:Administration, Oral; D000327:Adsorption; D000375:Aging / Q000378:metabolism; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology; D001682:Biological Availability; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D004305:Dose-Response Relationship, Drug; D004318:Doxycycline / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology; D005772:Gastrointestinal Transit / Q000187:drug effects; D006207:Half-Life; D007275:Injections, Intravenous / Q000662:veterinary; D011485:Protein Binding; D014422:Turkeys / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D004318:Doxycycline