Quantitative determination of oseltamivir and oseltamivir carboxylate in human fluoride EDTA plasma including the ex vivo stability using high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry

• Published in: Journal of chromatography. B, Analytical technologies in the biomedical and life sciences Analytical technologies in the biomedical and life sciences, 2012-04, Vol.891-892, p.57-63
• Main Authors: Kromdijk, W., Rosing, H., van den Broek, M.P.H., Beijnen, J.H., Huitema, A.D.R.
• Format: Article
• Language: English
• Subjects: Antiviral Agents - blood; Bioanalysis; blood; Carboxylates; Chromatography, High Pressure Liquid - methods; drugs; Edetic Acid - chemistry; EDTA; EDTA (chelating agent); electrospray ionization mass spectrometry; Fluorides; formic acid; high performance liquid chromatography; HPLC–MS/MS; Humans; Inhibitors; Ionization; Limit of Detection; Liquid chromatography; methanol; Orthomyxoviridae; Oseltamivir; Oseltamivir - blood; Oseltamivir carboxylate; Particle Size; Patients; Plasma; Quality Control; quantitative analysis; Reference Standards; Reproducibility of Results; spectrometers; Spectrometry, Mass, Electrospray Ionization - methods; Stability; tandem mass spectrometry; Tandem Mass Spectrometry - methods; trichloroacetic acid
• ISSN: 1570-0232; 1873-376X
• DOI: 10.1016/j.jchromb.2012.02.026

► Development of a HPLC–MS/MS assay for the determination of oseltamivir and oseltamivir carboxylate in plasma. ► Assessment of the ex vivo stability of oseltamivir in whole blood and plasma. ► Validation of the assay according to FDA guidelines. Oseltamivir, the ethyl ester prodrug of the neuramidase inhibitor oseltamivir carboxylate, is licensed for the treatment of patients with influenza virus infection. Here we describe the development and validation of an assay for the simultaneous quantification of oseltamivir and oseltamivir carboxylate in human fluoride EDTA plasma including the ex vivo stability using liquid chromatography coupled to tandem mass spectrometry. Sample pretreatment consisted of protein precipitation with 8% (v/v) trichloroacetic acid in water using only 50μL plasma. Chromatographic separation was performed on a reversed phase C18 column (150mm×2.0mm ID, particle size 4μm) with a stepwise gradient using 0.1% formic acid and methanol at a flow rate of 250μL/min. A triple quadrupole mass spectrometer operating in the positive ionization mode was used for detection and drug quantification. The method was validated over a range of 3–300ng/mL for oseltamivir and 10–10,000ng/mL for oseltamivir carboxylate. Deuterated oseltamivir and oseltamivir carboxylate were used as internal standards. The intra-assay accuracies and precisions for oseltamivir were between −8.8 and 16.3% at the LLOQ level, whereas for all other concentration levels this was −8.6 and 14.5%. For oseltamivir carboxylate the intra-assay accuracies and precisions were between −10.9 and 10.7% at all levels. Furthermore, oseltamivir was stable in plasma and whole blood ex vivo in commercially available fluoride EDTA tubes for at least 24h at 2–8°C. This method is now applied for the determination of both compounds in specific patient populations to evaluate current dosing guidelines.