Pharmacokinetics and protein binding of morphine in horses.
Morphine could be detected in horses dosed with 0.1 mg of drug/kg of body weight for up to 48 hours in blood and 144 hours in urine. This dose of morphine elicited no observable effects and is a suggested analgesic dose. Computer analysis revealed that a 3-compartment open system was the best fitting model with a serum half life (t1/2(beta)) of 87.9 minutes and a urine t1/2(beta) of 101.1 minutes. Binding to equine serum proteins was linear over a drug concentration range of 3.88 X 10(-5)M to 3.50 X 10(-8)M and averaged 31.6%. In RBC-partitioning experiments, 78.1% of the drug was found in the plasma fraction. The data indicated that a horse should not be given morphine closer than 1 week before a race.
D000818:Animals; D001800:Blood Specimen Collection / Q000662:veterinary; D003201:Computers; D003956:Dialysis / Q000662:veterinary; D004912:Erythrocytes / Q000378:metabolism; D005260:Female; D006207:Half-Life; D006736:Horses / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008954:Models, Biological; D009020:Morphine / Q000008:administration & dosage / Q000032:analysis / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D012709:Serum Albumin / Q000494:pharmacology; D013997:Time Factors
D012709:Serum Albumin; D009020:Morphine