Yaoguo Shi

Safety and clinical pharmacokinetics of nemonoxacin, a novel non-fluorinated quinolone, in healthy Chinese volunteers following single and multiple oral doses.

AbstractBackground: Nemonoxacin, a novel C-8-methoxy non-fluorinated quinolone, is currently being developed in oral and intravenous formulations. It exhibits potent antibacterial activities against Gram-positive, Gram-negative and atypical pathogens, especially methicillin-resistant Staphylococcus aureus. The first-in-human study of a nemonoxacin capsule was conducted in a Western population. This current study was the first investigation on the clinical pharmacokinetics (PK) of nemonoxacin in a Chinese population, and was designed to determine PK data in a Chinese population and investigate the dose regimen for future clinical use. Objective: The objective of this study was to evaluate the PK profile of nemonoxacin as well as its safety and tolerability in healthy Chinese volunteers following single and multiple oral doses. Methods: The first part of the study was a double-blind, placebo-controlled, sequential ascending single-dose safety and tolerability study. In each cohort, two subjects received a placebo and six received single oral doses of nemonoxacin 125, 250, 500, 750 or 1000 mg. In the second part, the single-dose PK study, three dose levels (250, 500 and 750 mg) of nemonoxacin were administered orally to 12 healthy Chinese volunteers (male: female = 1:1) under fasting conditions in a crossover manner. The same volunteers received orally an additional dose of 500 mg under fed conditions after a 7-day washout. In the third part, the multiple-dose PK study, 24 subjects received 500 or 750 mg of nemonoxacin orally once daily for 10 consecutive days. Within each cohort, 12 subjects (male: female = 1:1) received the same dose level of nemonoxacin under fasting conditions. The PK profiles, safety and tolerability, and food and sex effects were evaluated. Results: No severe or serious adverse events (AEs) occurred in this study, and no clinically significant abnormalities were noted in the vital signs or on physical examination. Notable AEs, mainly nausea and rash with or without pruritus, were mild and resolved spontaneously. Most laboratory AEs were mild and transient and the subjects recovered without treatment. Nemonoxacin was found to be rapidly absorbed, with peak plasma concentrations (Cmax) attained 1–2 hours after administration. The Cmax and area under the concentration-time curve from time zero to infinity (AUC∞) were dose-proportional after single oral doses. The elimination half-life was 10–12 hours. Nemonoxacin was excreted primarily in urine, with a recovery of intact nemonoxacin of 60–70% of the dose over 72 hours. Food had a significant effect on the rate and extent of absorption (p<0.001), increasing the time to reach Cmax from 1.14 to 3.64 hours and reducing Cmax by 34% and AUC∞ by 18%, while a sex effect was not found. Cmax and AUC∞ were similar between the single-dose and multiple-dose PK studies. The multiple-dose PK data suggested no drug accumulation in healthy subjects. Conclusion: Nemonoxacin exhibited a linear PK profile in the 250–750 mg dose range with moderate food effects. There was no accumulation following consecutive administration for 10 days. The PK and safety profiles of nemonoxacin in Chinese subjects support evaluation of once-daily dosing in the future development of this agent.

Pathogenic Implication of a Fibrinogen-Binding Protein of Staphylococcus epidermidis in a Rat Model of Intravascular-Catheter-Associated Infection

ABSTRACT The involvement of Fbe, a fibrinogen-binding protein of Staphylococcus epidermidis, in the pathogenesis of catheter-associated infection was investigated. An fbe (gene encoding Fbe protein) mutant was constructed by allelic replacement, wherein an erythromycin resistance gene replaced a portion of the A region of fbe. Meanwhile, a rat central venous catheter (CVC) infection model was established to assess the importance of Fbe in the pathogenesis of CVC-associated infection due to S. epidermidis. Fbe-positive S. epidermidis strain HB was significantly more likely to cause a CVC-associated infection resulting in bacteremia and metastatic disease than its isogenic Fbe-deficient mutant (100% versus 20%, P < 0.01). These results confirm the importance of adherence associated with Fbe in the pathogenesis of CVC-associated infection caused by S. epidermidis.

Liquid chromatography/tandem mass spectrometry assay for the simultaneous determination of cefoperazone and sulbactam in plasma and its application to a pharmacokinetic study

A rapid and highly sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for simultaneous determination of cefoperazone sodium and sulbactam sodium in human plasma was developed. The analytes and internal standard (IS), cefuroxime sodium, were extracted from human plasma via liquid-liquid extraction with ethyl acetate and separated on a Waters Xterra C18 column within 3.5 min. Quantitation was performed on a triple quadrupole mass spectrometer employing electrospray ionization technique, operating in selected reaction monitoring (SRM) and negative ion mode. The precursor to product ion transitions monitored for cefoperazone, sulbactam and IS were m/z 644.1→528.0, 232.1→140.0, and 423.0→362.0, respectively. The assay was validated in the linear range of 0.1-20 μg/mL for cefoperazone and 0.02-4 μg/mL for sulbactam. The intra- and inter-day precisions (CV%) were within 8.39% for each analyte. The recoveries were greater than 87.3% for cefoperazone and 87.2% for sulbactam. Each analyte was found to be stable during all sample storage, preparation and analytical procedures. The method was successfully applied in a pharmacokinetic study of Sulperazon injection in six hospital-acquired pneumonia (HAP) patients.

A liquid chromatography–tandem mass spectrometry assay for the determination of nemonoxacin (TG-873870), a novel nonfluorinated quinolone, in human plasma and urine and its application to a single-dose pharmacokinetic study in healthy Chinese volunteers

Nemonoxacin (TG-873870) is a novel C-8-methoxy nonfluorinated quinolone with higher activity than ciprofloxacin, levofloxacin and moxifloxacin against Gram-positive pathogens including methicillin-susceptible or methicillin-resistant Staphylococcus aureus and Streptococcus pneumoniae with various resistant phenotypes. A rapid, sensitive and selective liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed and validated to determine the concentration of nemonoxacin in human plasma and urine. Protein precipitation and liquid-liquid extraction were employed for plasma and urine sample preparations, respectively, and extract was then injected into the system. Separation was performed on a C(18) reversed-phase column using acetonitrile-0.1% formic acid as a mobile phase. Both analyte and internal standard (gatifloxacin) were determined using electrospray ionization and the MS data acquisition via the selected reaction monitoring in positive-ion mode. The lower limit of quantification was 5 ng/mL and the calibration curves were linear in the concentration range of 5-1000 ng/mL. The accuracy, precision, selectivity, linearity, recovery, matrix effect and stability were validated for TG-873870 in human plasma and urine. The method was successfully applied to a pharmacokinetic study enrolling 12 healthy Chinese volunteers administered nemonoxacin malate capsules.

Population pharmacokinetics of oral levofloxacin 500 mg once-daily dosage in community-acquired lower respiratory tract infections: results of a prospective multicenter study in China

This study aimed to explore the pharmacokinetic features of levofloxacin (LVFX) in Chinese patients with infections and to confirm oral LVFX 500 mg once daily as an optimal treatment regimen based on pharmacokinetic-pharmacodynamic (PK-PD) analysis. A total of 1052 plasma samples from 164 Chinese adult patients with communityacquired lower respiratory tract infections (CALRTIs) and 18 healthy volunteers were used for population PK analysis. LVFX 500-mg tablets were given once daily. A nonlinear mixed effects model (NONMEM) program was used for population PK model-building and a two-compartment model with first-order absorption process was established. Creatinine clearance (CLcr) and body weight were identified as intrinsic factors which significantly affected oral clearance (CLt/F) and the apparent volume of distribution of the central compartment (V1/F), respectively. The final model is described as follows: CLt/F (l/h) = (8.97 + 0.917 × (CLcr (ml/min) − 100.92) × 60/1000) × exp (ηCLt/F). V1/F (l) = (85.3 + 1.22 × (weight (kg) − 60.75)) × exp (ηV1/F). Q/F (l/h) = 0.351. V2/F (l) = 6.81. ka (h−1) = 1.44 × exp(ηka). Based on the population PK model, mean Cmax and AUC0–24h in CALRTI patients were estimated as 5.13 µg/ml and 58.98 µg·h/ml, respectively. A subgroup analysis showed that patients with mild renal dysfunction (50 ml/min ≤ CLcr < 80 ml/min) had 34% higher AUC0–24h values compared to patients with normal renal function (CLcr ≥ 80 ml/min). Postmodeling simulation using final population PK estimates also showed that Cmax and AUC0–24h increased markedly in patients with severe renal dysfunction. The results indicate that LVFX dosage adjustment should be individualized on the basis of the CLcr, especially in those with CLcr less than 50 ml/min. None of the PK parameters had any correlation with the occurrence of adverse events. PK-PD analysis indicated that, in patients treated with LVFX 500 mg once daily, the AUC0–24h/MIC ratio exceeded the target for those major CALRTI pathogens isolated. In addition, the Cmax/MIC ratio reached 5 for Streptococcus pneumoniae, indicating that the emergence of LVFX-resistant S. pneumoniae could be prevented during the therapy with this dosage regimen. These results demonstrate that oral LVFX 500 mg once daily has favorable PK parameters and PK-PD features in patients with CALRTIs, and the results strongly support this dosage regimen for the treatment of CALRTI.

Permeability and Concentration of Levofloxacin in Epithelial Lining Fluid in Patients With Lower Respiratory Tract Infections

The purpose of the study was to assess the bactericidal effects of a single oral dose of levofloxacin (LVFX) by examining the concentration of LVFX in alveolar epithelial lining fluid (ELF) from patients with lower respiratory tract infections (LRTI). Forty patients with LRTI took 500 mg of LVFX and then received a fiberoptic bronchoscopic procedure randomly 1, 4, 8, 12, or 24 hours following dosing. Bronchoalveolar lavage fluid and blood were collected at the time of the bronchopulmonary procedure, and the LVFX concentration was determined. The mean peak concentrations of LVFX in plasma and ELF were achieved at 1.5 hours (4.07 mg/L) and 1 hour (3.44 mg/L), respectively. The AUC24h samples were 50.12 mg · h/L and 34.51 mg · h/L, respectively. The permeability of LVFX, which was estimated based on the ratio of LVFX concentration in tissue fluids to that in plasma, was 0.78 on average across all time points. After a single dose of LVFX in patients with LRTI, the drug rapidly distributed into bronchopulmonary tissue, thereby suggesting this dose is capable of achieving the concentration in target organs required for bactericidal efficacy.

Quantification of levornidazole and its metabolites in human plasma and urine by ultra-performance liquid chromatography–mass spectrometry

We developed and validated an ultra-performance liquid chromatographic (UPLC) method coupled with atmospheric pressure chemical ionization (APCI) mass spectrometry for simultaneous determination of levornidazole and its first-pass metabolites, l-chloro-3-(2-hydroxymethyl-5-nitro-l-imidazolyl)-2-propanol (Ml), 2-methyl-5-nitroimidazole (M2) and 3-(2-methyl-5-nitro-1-imidazolyl)-1,2-propanediol (M4), in human plasma and urine. The biological samples were pretreated by protein precipitation and liquid-liquid extraction and analyzed using an ACQUITY UPLC CSH C18 column (2.1×50 mm, 1.7 μm) and a QTRAP mass spectrometer in multiple reaction monitoring mode via APCI. Acetonitrile and 0.1% formic acid in water was used as the mobile phase in gradient elution at a flow rate of 0.6 mL/min. The lower limit of quantification of this method was 0.0100, 0.00500, 0.0200 and 0.00250 μg/mL for levornidazole, M1, M2 and M4, respectively. The linear calibration curves were obtained for levornidazole, M1, M2, and M4 over the range of 0.0100-5.00, 0.00500-2.50, 0.0200-10.0 and 0.00250-1.25 μg/mL, respectively. The intra- and inter-batch precision was less than 12.2% in plasma and less than 10.8% in urine. The intra- and inter-batch accuracy was 87.8-105.7% in plasma and 92.8-109.2% in urine. The mean recovery of levornidazole, M1, M2 and M4 was 91.1-105.1%, 95.8-103.8%, 87.8-96.8%, 96.8-100.6% from plasma and 96.0-100.9%, 96.9-107.9%, 95.1-102.7%, 103.7-105.9% from urine respectively. This method was validated under various conditions, including room temperature, freeze-thaw cycles, long-term storage at -40 ± 5°C, after pretreatment in the autosampler (at 10°C), and 10- and 100-fold dilution. This newly established analytical method was successfully applied in a pharmacokinetic study following single intravenous infusion of levornidazole in 24 healthy Chinese subjects.

Establishment of norvancomycin fluorescence polarization immunoassay for therapeutic drug monitoring.

To establish a rapid and simple fluorescence polarization immunoassay method for determination of norvancomycin serum concentration, we collected 300 serum samples from the patients receiving norvancomycin in the hospitals localized in Shanghai, China. The drug concentrations were measured by the established HPLC method and FPIA with vancomycin kit. A FPIA algorithm for the determination of norvancomycin concentration was established according to the correlation between the FPIA and HPLC results. The methods and algorithm were validated in another 70 clinical samples. HPLC determination showed a good linear correlation within the range of 0.5–100 mg l−1 of norvancomycin concentrations. The method was validated via extraction recovery, intra- and inter-day methodological recovery and stability of norvancomycin in serum. Correlation analysis between the measurements of HPLC and FPIA in 300 serum samples gave the linear regression equation: (concentration by HPLC)=0.760 × (concentration by FPIA)–0.577 (P<0.001, R2=0.982). An algorithm was derived from this correlation for measuring the serum norvancomycin concentrations with FPIA. When it was validated in additional 70 serum samples from patients, ‘FPIA algorithm’ showed good accuracy versus HPLC: ‘FPIA algorithm’=0.93 (HPLC)+0.63, R2=0.962, and 94.3% of the results from FPIA algorithm fell within the range of −20%/+20% of HPLC. This algorithm developed in this study can be easily used for determination of norvancomycin using TDx analyzer with vancomycin kit indirectly. It may also be useful for norvancomycin therapeutic drug monitoring.

Improved pharmacokinetic profile of levornidazole following intravenous infusion of 750 mg every 24 h compared with 500 mg every 12 h in healthy Chinese volunteers

Levornidazole is the levo-isomer of ornidazole with similar anti-anaerobic activity and lower central neurotoxicity compared with ornidazole. This open-label, parallel, randomised, multidose trial was conducted to compare the pharmacokinetics and safety of levornidazole following intravenous (i.v.) infusion 750mg every 24h (q24h) (test group, 12 subjects) versus 500mg every 12h (q12h) (reference group, 12 subjects) for 7 days in healthy Chinese volunteers. Following i.v. infusion for 7 days, the test group showed a 33.8% lower accumulation ratio (AR) and a 45.0% higher volume of distribution of levornidazole than the reference group. The cumulative urinary excretion rate of levornidazole during the 0-72h period (Ae0-72) was 16.6±20.9% in the test group and 24.2±5.7% in the reference group. The metabolite M1/parent and M4/parent ratios were, respectively, 2.18±0.77% and 2.94±0.37% in test group and 3.15±1.09% and 3.18±0.34% in the reference group. The Ae0-72 of M1, M2 and M4 were all <10% in both groups. Both regimens were well tolerated. Drug-related adverse events were generally transient and were mild or moderate in severity. These findings support the recommendation of i.v. infusion of levornidazole 750mg q24h in clinical practice, which shows a lower AR and similar safety compared with the conventional 500mg q12h regimen. [Chinese Clinical Trial Registry identifier: ChiCTR-IPR-14005574.].

Safety, Tolerability, and Pharmacokinetics of Intravenous Nemonoxacin in Healthy Chinese Volunteers

ABSTRACT Nemonoxacin (TG-873870) is a novel nonfluorinated quinolone with potent broad-spectrum activity against Gram-positive, Gram-negative, and atypical pathogens, including vancomycin-nonsusceptible methicillin-resistant Staphylococcus aureus (MRSA), quinolone-resistant MRSA, quinolone-resistant Streptococcus pneumoniae, penicillin-resistant S. pneumoniae, and erythromycin-resistant S. pneumoniae. This first-in-human study was aimed at assessing the safety, tolerability, and pharmacokinetic properties of intravenous nemonoxacin in healthy Chinese volunteers. The study comprised a randomized, double-blind, placebo-controlled, dose escalating safety and tolerability study in 92 subjects and a randomized, single-dose, open-label, 3-period Latin-square crossover pharmacokinetic study in 12 subjects. The study revealed that nemonoxacin infusion was well tolerated up to the maximum dose of 1,250 mg, and the acceptable infusion rates ranged from 0.42 to 5.56 mg/min. Drug-related adverse events (AEs) were mild, transient, and confined to local irritation at the injection site. The pharmacokinetic study revealed that after the administration of 250, 500, and 750 mg of intravenous nemonoxacin, the maximum plasma drug concentration (Cmax) values were 4.826 μg/ml, 7.152 μg/ml, and 11.029 μg/ml, respectively. The corresponding values for the area under the concentration-time curve from 0 to 72 hours (AUC0–72 h) were 17.05 μg · h/ml, 39.30 μg · h/ml, and 61.98 μg · h/ml. The mean elimination half-life (t1/2) was 11 h, and the mean cumulative drug excretion rate within 72 h ranged from 64.93% to 77.17%. Volunteers treated with 250 to 750 mg nemonoxacin exhibited a linear dose-response relationship between the AUC0–72 h and AUC0–∞. These findings provide further support for the safety, tolerability, and pharmacokinetic properties of intravenous nemonoxacin. (This study has been registered at ClinicalTrials.gov under registration no. NCT01944774.)