title: Warfarin pharmacokinetics in the horse.
abstract: The pharmacokinetics of racemic warfarin were studied in 6 adult horses. After IV administration, the plasma concentration of warfarin showed a biphasic decline in time. Analysis of the data, according to 2-compartment kinetics, revealed the following constants: biological half-life was 13.3 hours, apparent volume of distribution was 0.46 L X kg-1, body clearance was 25.3 ml X hour-1 X kg-1. Warfarin was bound (91.5%) to plasma proteins. Unchanged warfarin was not detected in the urine. Absorption from the gastrointestinal tract was almost complete. Concentrations of warfarin in tissue were examined in 4 foals that were given 1 g of warfarin orally 14 hours before they were euthanatized. The concentrations in the kidney were higher than those in plasma (about 2 fold). The hypothrombogenic effect of the acute IV and oral administration of warfarin (0.75 mg/kg of body weight) was noticeable only after 60 hours and lasted for about 30 hours. The effect was weak; the maximum effect was a prolongation of 2.3 s (from 11.5 s to 13.8 s) in thromboplastin time.
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001682:Biological Availability; D005260:Female; D006207:Half-Life; D006736:Horses / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D014018:Tissue Distribution; D014859:Warfarin / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*
chemical_list: D014859:Warfarin