Dialyzability and pharmacokinetics of sitafloxacin following multiple oral dosing in infected hemodialysis patients

Effects of ABCB1, UGT1A1, and UGT1A9 Genetic Polymorphisms on the Pharmacokinetics of Sitafloxacin Granules in Healthy Subjects

Sitafloxacin, a new fluoroquinolone, has strong antibacterial activity. We evaluated the effects of sitafloxacin granules in single‐dose and multidose cohorts and the effects of ABCB1, UGT1A1, and UGT1A9 genetic polymorphisms on the pharmacokinetics (PK) of sitafloxacin in healthy subjects. The single‐dose study included 3 fasted cohorts receiving 50, 100, and 200 mg of sitafloxacin granules and 1 cohort receiving 50 mg of sitafloxacin granules with a high‐fat meal. The multidose study included 1 cohort receiving 100 mg of sitafloxacin granules once daily for 5 days. PK parameters were calculated using noncompartmental parameters based on concentration‐time data. The genotypes for ABCB1, UGT1A1, and UGT1A9 single‐nucleotide polymorphisms were determined using Sanger sequencing. Subsequently, the association between sitafloxacin PK parameters and target single‐nucleotide polymorphisms was analyzed. Sitafloxacin granules were well tolerated up to 200 and 100 mg in the single‐dose and multidose studies, respectively. Sitafloxacin AUC and C_max increased linearly within the detection range, and a steady state was reached within 3 days after the administration of multiple oral doses. Our findings showed that C_max was lower in the ABCB1 (rs1045642) mutation group, whereas t_1/2 was longer in the UGT1A1 (rs2741049) and UGT1A9 (rs3832043) mutation groups. In conclusion, sitafloxacin granules were safe at single doses and multiple doses up to 200 and 100 mg/day, respectively, with a linear plasma PK profile. However, ABCB1 (rs1045642), UGT1A1 (rs2741049), and UGT1A9 (rs3832043) genetic polymorphisms are likely to influence the C_max or t_1/2 and thereby merit further clinical evaluation.

Dialyzability of Faropenem in Infected Patients on Chronic Hemodialysis

The aim of this study was to evaluate the profile of dialyzability of an oral penem antibiotic, faropenem (FRPM), in hemodialysis (HD) patients with infections. Eight patients took one tablet of FRPM (200 mg) every 12 h during an inter-dialysis period, and another tablet at 1-5 h before the beginning of the HD session. Blood samples were obtained during the HD session (3-4 h). Plasma FRPM concentrations in the arterial side were 4.8 ± 2.5 and 2.8 ± 1.0 µg/mL before and at the end of HD session, respectively, which are above the 50% minimal inhibitory concentrations of FRPM against the major pathogen (0.015-2 µg/mL). Dialyzer clearance and elimination fraction of FRPM were 14.9 ± 6.8 mL/min per m² and 20.4 ± 9.9%, respectively. About 2% of FRPM was removed from the body during a single HD session. The infection-related symptoms, the white blood cell count and the level of C-reactive protein were improved by FRPM without any adverse effects. These data suggest that the dialyzability of FRPM is relatively low, and the amount of the drug removed by a single HD session is small. FRPM 200 mg twice daily might provide an effective and safe dosage regimen without additional dosing at the end of the HD session.

A simple LC-MS/MS method for determination of sitafloxacin in human urine

Sitafloxacin is a new fluoroquinolone antimicrobial agent with high activity. In this article, we reported a simple, rapid and specific LC-MS/MS method for accurate determination of sitafloxacin concentrations in human urine from healthy volunteers in detail. A two-step dilution method for the analysis of sitafloxacin in human urine using LC coupled to positive MS/MS has been developed and validated according to US FDA guidelines and Chinese State Food and Drug Administration (CFDA) guidelines for the validation of bioanalytical methods. The method uses 50 μL of urine and covers a working range from 0.025 to 20 μg/mL with a LLOQ of 0.025 μg/mL. This new LC-MS/MS assay is sensitive and specific.

Determination of sitafloxacin in human plasma by liquid chromatography-tandem mass spectrometry method: application to a pharmacokinetic study

A high-performance liquid chromatographic-tandem mass spectrometric (HPLC-MS/MS) method was developed and validated to determine sitafloxacin in human plasma with dextrorphan as internal standard. Chromatographic separation was performed on a ZORBAX SB-C18 column (3.5μm, 2.1mm×100mm) with the mobile phase of methanol/water (containing 0.1% formic acid) (46:54, v/v) at a flow rate of 0.2mL/min. Quantification was performed using multiple-reaction monitoring of the transitions at m/z 410.2 → 392.2 for sitafloxacin and m/z 258.1 → 157.1 for dextrorphan, respectively. The calibration curve was linear over the range of 5-2500ng/mL with the lower limit of quantification of 5ng/mL for sitafloxacin. The intra- and inter-day precisions were less than 8.3% and the deviations of assay accuracies were within ±4.1%. Sitafloxacin was sufficiently stable under all relevant analytical conditions. This method was successfully applied to the pharmacokinetic study of sitafloxacin in healthy Chinese volunteers.