Affordable Access

Pharmacokinetics of oral doxycycline and concentrations in body fluids and bronchoalveolar cells of foals.

Authors
Type
Published Article
Journal
Journal of veterinary pharmacology and therapeutics
Publication Date
Volume
30
Issue
3
Pages
187–193
Identifiers
PMID: 17472649
Source
Medline
License
Unknown

Abstract

The objective of this study was to determine the disposition of orally administered doxycycline in foals. Six healthy 4- to 8-week-old foals were used. Doxycycline was administered to each foal via the intragastric (IG) route at dosages of 10 and 20 mg/kg, in a cross-over design. After the first 10 mg/kg dose, five additional doses were administered at 12-h intervals. A microbiological assay was used to measure doxycycline activity in serum, urine, peritoneal fluid, synovial fluid, cerebrospinal (CSF), pulmonary epithelial lining fluid (PELF), and bronchoalveolar (BAL) cells. Following administration at 10 mg/kg, mean+/-SD time to peak serum doxycycline activity (tmax) was 3.0+/-1.2 h, maximum serum activity (Cmax) was 2.54+/-0.27 microg/mL, and terminal half-life (t1/2) was 8.5+/-2.8 h. Administration at a dose of 20 mg/kg resulted in a significantly longer tmax (5.5+/-1.8 h) as well as a tendency toward higher Cmax (2.89+/-0.33 microg/mL) and longer t1/2 (11.9+/-2.6 h). After multiple IG doses, doxycycline activity in CSF was significantly lower than concurrent serum activity, whereas peritoneal fluid, synovial fluid, and BAL cell doxycycline activity was similar to concurrent serum activity. Doxycycline activity in urine and PELF was significantly higher than that found at other sites. Oral administration at a dosage of 10 mg/kg every 12 h would maintain serum, PELF, and BAL cell activity above the minimum inhibitory concentrations of Rhodococcus equi, beta-hemolytic streptococci, and other susceptible bacterial pathogens for the entire dosing interval.

Statistics

Seen <100 times