Development of a useful single-reference HPLC method for therapeutic drug monitoring of phenytoin and carbamazepine in human plasma

• Published in: Analytical sciences 2023-04, Vol.39 (4), p.447-454
• Main Authors: Sakaguchi, Yuko, Arima, Ryo, Maeda, Runa, Obayashi, Takuji, Masuda, Akihide, Funakoshi, Mari, Tsuchiya, Yumi, Ichikawa, Nobuhiro, Inoue, Koichi
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Carbamazepine; Chemistry; Chemistry and Materials Science; Chromatography, High Pressure Liquid - methods; Drug Monitoring; Humans; Phenytoin; Special Issue: Original Paper
• ISSN: 0910-6340; 1348-2246
• DOI: 10.1007/s44211-023-00266-z

A single reference high-performance liquid chromatographic (SR-HPLC) method was developed and validated for the therapeutic drug monitoring (TDM) of phenytoin (PHT) and carbamazepine (CBZ) in plasma from patients. The analytical parameters evaluated were linearity, limit of quantification (LOQ), selectivity, accuracy, and stability according to the US Food and Drug Administration (FDA) guideline. The developed method shows good linearity (r2 > 0.999; LOQ—50 µg/mL), and LOQ values were 1.56 µg/mL for PHT and 0.40 µg/mL for CBZ at 254 nm. For the development of SR-HPLC method, we evaluated to improve the detection wavelength, stirred retention time, and stability for SR, and selected 5-(p-methylphenyl)-5-phenylhydantoin for PHT (relative molar sensitivity, RMS = 0.848) and 10-methoxyiminostilbene for CBZ (RMS = 0.263). The established differential definite quantities of PHT and CBZ in plasma samples were similar using the RMS and absolute calibration methods based on RSD