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Quantification of phenytoin and its metabolites in equine plasma and urine using high-performance liquid chromatography

2000; Elsevier BV; Volume: 746; Issue: 2 Linguagem: Inglês

10.1016/s0378-4347(00)00330-3

1872-812X

Fuyu Guan, Cornelius E. Uboh, Lawrence R. Soma, Eric K. Birks, D. Teleis, Jeffrey A. Rudy, Anthony O. Watson, Deborah S. Tsang,

Drug Transport and Resistance Mechanisms

A reliable and sensitive method for the extraction and quantification of phenytoin (5,5′-diphenylhydantoin), its major metabolite, 5-(p-hydroxyphenyl)-5-phenylhydantoin (p-HPPH) and minor metabolite, 5-(m-hydroxyphenyl)-5-phenylhydantoin (m-HPPH) in horse urine and plasma is described. The method involves the use of solid-phase extraction (SPE), liquid–liquid extraction (LLE), enzyme hydrolysis (EH) and high-performance liquid chromatography (HPLC). The minor metabolite, 5-(m-hydroxyphenyl)-5-phenylhydantoin (m-HPPH) was not present in a reliably quantifiable concentration in all samples. The new method described was successfully applied in the pharmacokinetic studies and elimination profile of phenytoin and p-HPPH following oral or intravenous administration in the horse.