Antipyrine pharmacokinetics and urinary excretion in female horses.

Abstract

OBJECTIVE: To measure renal clearance of antipyrine and urinary excretion of antipyrine (AP) metabolites in horses by use of validated high-performance liquid chromatography (HPLC) methods. ANIMALS: 8 Standardbred mares. PROCEDURE: HPLC methods for measurement of AP in equine plasma and AP and its metabolites in equine urine were validated. Antipyrine (20 mg/kg of body weight) was administered i.v., and blood samples and urine specimens were collected over 24 hours. RESULTS: Median plasma clearance of AP in horses was 6.2 ml/min/kg, of which < 2% could be attributed to renal clearance. Urinary excretion of AP and its metabolites over 24 hours accounted for < 22% of the AP dose administered. ..