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  • Author or Editor: Libin Wang x
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A simple, sensitive, and rapid liquid chromatography–tandem mass spectrometry (LC–MS/MS) method has been developed and validated for determination of phloretin in dog plasma using darunavir as internal standard. The phloretin was separated by the Inertsil® ODS3 C18 column (150 mm × 4.6 mm, 5 μm) and determined by LC–MS/MS. The electrospray ionization (ESI) source was operated in negative ionization mode for phloretin and positive ionization mode for darunavir (internal standard, IS). The multiple reaction monitoring (MRM) transitions were chosen to be m/z 273.0 → m/z 148.9 for phloretin, m/z 443.2 → m/z 401.0 for 2′,4′,6′,4-tetra-acetylphloretin and m/z 548.1 → m/z 69.1 for IS. The method was validated for accuracy, precision, linearity, range, selectivity, lower limit of quantification (LLOQ), recovery, and matrix effect. All validation parameters met the acceptance criteria according to regulatory guidelines. 2′,4′,6′,4-Tetra-acetylphloretin, as a prodrug of phloretin, is more stable than phloretin (PH) in vitro, protecting phenolic hydroxy from being oxygenated. The method had been successfully applied to a pharmacokinetic study of administration of phloretin and 2′,4′,6′,4-tetra-acetylphloretin in beagle dogs. Significant differences of t max, C max, and area under the plasma concentration curve (AUC) were observed between phloretin and 2′,4′,6′,4-tetra-acetylphloretin.

Open access

2′,4′,6′,4-Tetra-O-acetylphloretin (TAPHL) is a prodrug of phloretin (PHL) in which the OH groups are protected by acetylation. A validated liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for the determination of PHL in rat biological matrices was developed and applied to investigate and compare the pharmacokinetics, tissue distribution, and excretion of PHL and TAPHL in rats following a single oral administration. The method was validated for accuracy, precision, linearity, range, selectivity, lower limit of quantification (LLOQ), recovery, and matrix effect. All validation parameters met the acceptance criteria according to regulatory guidelines. The mean pharmacokinetic parameters of t max, C max, AUC(0 − t), CL/F, and t 1/2 were observed after oral administration in rats. The data showed that PHL was absorbed and eliminated rapidly from plasma after oral administration. The pharmacokinetic properties are improved, such as the t max has been prolonged and the area under the curve (AUC) has been enhanced after oral administration of TAPHL to rats. Tissue distribution results indicated that PHL could be rapidly and widely distributed into tissues but could not effectively cross the blood–brain barrier in rats. After oral administration of TAPHL to rats, its tissue distribution to rats was similar as that after oral administration of equimolar PHL. In addition, higher recoveries of PHL following administration of TAPHL indicated that TAPHL might reduce the excretion of PHL from the body by reducing the first pass effect.

Open access

A simple, rapid, and sensitive liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and validated for the simultaneous quantitation of PA-824 and moxifloxacin in rat plasma using carbamazepine as an internal standard (IS). The sample preparation involved a one-step protein precipitation method with methanol. The separation was performed on Inertsil® ODS3 C18 column (150 mm × 4.6 mm, 5 μm) and maintained at 30 °C. The mobile phase consisted of 0.1% formic acid in acetonitrile–water (90:10 v/v) with fast isocratic elution at a flow rate of 0.6 mL/min and a run time of 10 min. A mass spectrometer was run in the positive ion electrospray ionization (ESI) mode using multiple reaction monitoring (MRM) to monitor the mass transitions. The MRM transitions were chosen to be m/z 360.1 → m/z 175.0 for PA-824, m/z 402.0 → m/z 383.9 for moxifloxacin, and m/z 237.1 → m/z 194.0 for IS. The method was fully validated in terms of selectivity, linearity, accuracy, precision, matrix effect, recovery, and stability, respectively. The method was successfully applied to drug–drug interaction (DDI) study of PA-824 and moxifloxacin in rats. The results show that the main pharmacokinetic parameters of PA-824, namely, T max, t 1/2, and AUC(0–t), increased more in the PA-824 and moxifloxacin group than in the PA-824 group. However, there were little changes in the main pharmacokinetic parameters of moxifloxacin from single and combined groups.

Open access