Sensitive method for the determination of phenytoin in plasma, and phenytoin and 5-(4-hydroxyphenyl)-5-phenylhydantoin in urine by high-performance liquid chromatography

• Published in: Journal of pharmaceutical and biomedical analysis 1992-10, Vol.10 (10), p.1001-1006
• Main Authors: Maya, Manuela T., Farinha, Ascensa˜o R., Lucas, Anto´nio M., Morais, Jose´A.
• Format: Article
• Language: English
• Subjects: 5-(4-hydroxyphenyl)-5-phenylhydantoin; Acetates - chemistry; Analysis; Biological and medical sciences; Chromatography, High Pressure Liquid; Diatomaceous Earth; Furans - chemistry; General pharmacology; High-performance liquid chromatography; Humans; Medical sciences; Methanol - chemistry; Pharmacology. Drug treatments; phenytoin; Phenytoin - analogs & derivatives; Phenytoin - blood; Phenytoin - urine; plasma; Resins, Plant - chemistry; urine; Water - chemistry
• ISSN: 0731-7085; 1873-264X
• DOI: 10.1016/0731-7085(91)80111-L

An isocratic high-performance liquid chromatographic method is described for the quantitative analysis of phenytoin (PHT) in plasma and both phenytoin and its main metabolite, 5-(4-hydroxyphenyl)-5-phenylhydantoin (p-HPPH) in urine. Following ethyl acetate (plasma) and Extrelut-1 (urine) extraction, samples are analysed by means of a reversed-phase column (Nova-Pak C 18), using a mobile phase consisting of methanol—water—tetrahydrofuran (40:60:4, v/v/v) with UV detection at 230 nm. The chromatography is complete in 10 min and the results show good precision (RSD 1.23–4.49%) and sensitivity for a linear range of 0.4–4.0 μg ml −1 for PHT in plasma, 0.1–1.0 μg ml −1 for PHT in urine and 0.1–1.2 μg ml −1 for p-HPPH in urine. The results indicate the method to be suitable for pharmacokinetic studies.