Pharmacokinetics of clarithromycin and concentrations in body fluids and bronchoalveolar cells of foals.
OBJECTIVE
To determine pharmacokinetics of clarithromycin and concentrations in body fluids and bronchoalveolar (BAL) cells of foals.


METHODS
6 healthy 2-to 3-week-old foals.


METHODS
In a crossover design, clarithromycin (7.5 mg/kg) was administered to each foal via IV and intragastric (IG) routes. After the initial IG administration, 5 additional doses were administered IG at 12-hour intervals. Concentrations of clarithromycin and its 14-hydroxy metabolite were measured in serum by use of high-performance liquid chromatography. A microbiologic assay was used to measure clarithromycin activity in serum, urine, peritoneal fluid, synovial fluid, CSF, pulmonary epithelial lining fluid (PELF), and BAL cells.


RESULTS
After IV administration, elimination half-life (5.4 hours) and mean +/- SD body clearance (1.27 +/- 0.25 L/h/kg) and apparent volume of distribution at steady state (10.4 +/- 2.1 L/kg) were determined for clarithromycin. The metabolite was detected in all 6 foals by 1 hour after clarithromycin administration. Oral bioavailability of clarithromycin was 57.3 +/- 12.0%. Maximum serum concentration of clarithromycin after multiple IG administrations was 0.88 +/- 0.19 microg/mL. After IG administration of multiple doses, clarithromycin concentrations in peritoneal fluid, CSF, and synovial fluid were similar to or lower than concentrations in serum, whereas concentrations in urine, PELF, and BAL cells were significantly higher than concentrations in serum.


CONCLUSIONS
Oral administration of clarithromycin at 7.5 mg/kg every 12 hours maintains concentrations in serum, PELF, and BAL cells that are higher than the minimum inhibitory concentration (0.12 microg/mL) for Rhodococcus equiisolates for the entire 12-hour dosing interval.
Womble
Ariel Y
AY
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610-0136, USA.
Giguère
Steeve
S
Lee
Elise A
EA
Vickroy
Thomas W
TW
D000284:Administration, Oral; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D019540:Area Under Curve; D001202:Ascitic Fluid / Q000378:metabolism; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology*; D017291:Clarithromycin / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D018592:Cross-Over Studies; D005260:Female; D006207:Half-Life; D006736:Horses / Q000378:metabolism*; D007275:Injections, Intravenous / Q000662:veterinary; D008297:Male; D013582:Synovial Fluid / Q000378:metabolism; D014018:Tissue Distribution
D000900:Anti-Bacterial Agents; D017291:Clarithromycin