Quantification of phenytoin and its metabolites in equine plasma and urine using high-performance liquid chromatography.
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.
Guan
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F
University of Pennsylvania School of Veterinary Medicine Department of Clinical Studies, Kennett Square 19348, USA.
Uboh
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CE
Soma
L R
LR
Birks
E K
EK
Teleis
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Rudy
J A
JA
Watson
A O
AO
Tsang
D S
DS
D000818:Animals; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006736:Horses; D010672:Phenytoin / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D010672:Phenytoin