Pharmacokinetics of Acyclovir after Single Intravenous and Oral Administration to Adult Horses

Autor: Bradford G. Bentz, Michael S. Davis, Lara K. Maxwell, Ronald S. Erkert, Cyril R. Clarke, Christopher M. Royer, Charles G. MacAllister
Rok vydání: 2006
Předmět:
Zdroj: Journal of Veterinary Internal Medicine. 20:589-594
ISSN: 1939-1676
0891-6640
DOI: 10.1111/j.1939-1676.2006.tb02901.x
Popis: The purpose of the study reported here was to describe the bioavailability and pharmacokinetics of acyclovir after intravenous and oral administration to horses. Six healthy adult horses were used in a randomized cross-over study with a 3×3 Latin square design. Three treatments were administered to each horse: 10 mg of injectable acyclovir/kg of body weight in 1 L of normal saline delivered as an infusion over 15 minutes; 10 mg of acyclovir/kg in tablets by nasogastric intubation; and 20 mg of acyclovir/kg in tablets by nasogastric intubation. A 2-week washout period was provided between each treatment. Serum samples were obtained for acyclovir assay using reversed-phase, high-performance liquid chromatography with fluorescence detection. Deproteinated serum was injected onto a C18 column, and elution occurred under isocratic conditions. The limit of quantification was 0.04 μg/mL. The assay exhibited suitable accuracy, precision, and recovery. The IV data were analyzed by a 3-compartment model, and oral data were analyzed noncompartmentally. Intragastric acyclovir administration at either dose was associated with high variability in serum acyclovir-time profiles, low Cmax, and poor bioavailability. The dosage of 20 mg/kg was associated with mean (± SD) Cmax of 0.19±0.10 μg/mL, and bioavailability was 2.8%. Inhibition of equine herpesvirus has been reported to require significantly higher acyclovir concentrations than those obtained here. The results of this study do not support a therapeutic benefit for the oral administration of acyclovir up to doses of 20 mg/kg.
Databáze: OpenAIRE
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