Determination of phenytoin in human plasma by a validated HPLC method: application to therapeutic drug monitoring study

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Dural E. , Bolayır A. , Çiğdem B.

Acta Pharmaceutica Sciencia, vol.59, no.1, pp.683-704, 2021 (Refereed Journals of Other Institutions)

  • Publication Type: Article / Article
  • Volume: 59 Issue: 1
  • Publication Date: 2021
  • Title of Journal : Acta Pharmaceutica Sciencia
  • Page Numbers: pp.683-704


The aim of this study was to develop a simple and reliable HPLC method for the determination of phenytoin (PHT) in human plasma. Accuracy (RE%) were determined between (-0.93%) to 2.49% and precision (RSD%) values was ≤7.94. The quantitation limit was 3.54 µg/mL and recovery was found between 82.15% and 101.06%. The method was applied to real plasma samples (n = 7). Plasma-PHT levels were found between 1.12 and 18.76 µg/mL (9.52 ± 7.78, mean±SD). Both the plasma and dose-rated plasma results of PHT showed so high RSD% which were between 81.74% and 89.61%. In addition plasma-PHT levels were outside the recommended treatment range in 4 of the 7 patients (57.14%) examined, and also surprisingly PHT could not be detected in a patient’s plasma. This procedure is relatively simple, precise, and applicable for routine therapeutic drug monitorization of PHT in neurology clinics or toxicological analyses in reference laboratories.

Keywords: Phenytoin, Human plasma, Therapeutic drug monitoring, Method validation, HPLC-UV.