Efficacy and Safety of Antofloxacin-Based Triple Therapy for Helicobacter pylori Eradication Failure in China.

AIMS: Quinolone-containing triple therapy has been considered as the second-line therapy for eradication of Helicobacter pylori (H. pylori). At present, there are no data to show the efficacy and safety of antofloxacin-based rescue therapy for the eradication of H. pylori, and this pilot clinical trial was designed. METHODS: A total of 196 patients who failed H. pylori eradication using the clarithromycin-based or metronidazole-based triple or bismuth quadruple therapy were randomly allocated to one of the following rescue eradication therapy groups: AEA group (antofloxacin 200 mg once daily, esomeprazole 20 mg + amoxicillin 1000 mg twice daily) for 14 days, or LEA group (levofloxacin 500 mg once daily, esomeprazole 20 mg + amoxicillin 1000 mg twice daily) for 14 days. The minimal inhibitory concentrations were tested by the E-test method. The gyrA mutation was analyzed by sequencing. Follow-up 13/14C-urea breath test was examined at 1 month after discontinuation. RESULTS: A total of 178 eligible patients were included in this study. The eradication rate was significantly higher in AEA group than in LEA group according to both ITT (87.6% vs. 68.5%; P = 0.002) and PP analyses (90.7% vs. 70.1%; P = 0.001). ITT analyses indicated that the eradication rate was significantly higher in AEA group than in LEA group with Asn87 mutation (78.9% vs. 31.3%; P = 0.005) and levofloxacin-resistant strains (76.9% vs. 44.2%; P = 0.003). Two groups exhibited similar adverse event rates (AEA 14.6% vs. LEA 20.2%, P = 0.323). CONCLUSIONS: The findings showed that antofloxacin may be a promising candidate in rescue therapy for H. pylori eradication failure in China.

Antofloxacin-based bismuth quadruple therapy is safe and effective in Helicobacter pylori eradication: A prospective, open-label, randomized trial.

BACKGROUND AND STUDY AIMS: The present study was designed to evaluate the safety, efficacy, and tolerability of antofloxacin-based bismuth quadruple therapy in Chinese patients with Helicobacter pylori infection. PATIENTS AND METHODS: Total 290 patients with H. pylori infection were randomly and equally divided into two groups as per different bismuth quadruple therapies for 14 d: colloidal bismuth pectin 200 mg thrice a day, lansoprazole 30 mg twice a day, amoxicillin 1 g twice a day, and antofloxacin 200 mg once a day (ACLA group) or levofloxacin 500 mg once a day (LCLA group). Eradication was assessed with 13C-urea breath test 6 wk after treatment completion; the primary endpoint was the eradication rate by intention-to-treat (ITT) and per-protocol (PP) analyses. The minimum inhibitory concentration was measured with the PDM epsilometer test to assess the susceptibility of H. pylori strains on gastric biopsy specimens to antofloxacin and levofloxacin. RESULTS: The eradication rates of H. pylori in the ACLA group were 93.8% and 97.8% for the ITT and PP analysis, respectively; these rates were significantly higher than those in the LCLA group, at 86.2% and 92.6%, respectively (p = 0.031 and 0.041, respectively). The total incidence of adverse events during the eradication therapy did not significantly differ between the ACLA and LCLA groups (31.7% vs. 37.9%%, p = 0.267), and the two groups displayed similar severity of adverse events (p = 0.156) and compliance rate (100% by ACLA vs. 97.8% by LCLA, p = 0.080). The eradication rate with the antofloxacin susceptible strains in the ACLA group was significantly higher than that with the resistant strains (99.2% vs. 66.7%, p = 0.045). Moreover, the eradication rate with the levofloxacin susceptible strains in the LCLA group was significantly higher than that with the resistant strains (95.3% vs. 80.0%, p = 0.013). CONCLUSION: Antofloxacin is safe and effective for H. pylori eradication. Antofloxacin-based bismuth quadruple therapy could be an alternative treatment for H. pylori eradication.

In Vivo Pharmacodynamic Target Assessment of Antofloxacin against Streptococcus pneumoniae and Staphylococcus aureus in a Neutropenic Murine Pneumonia Model.

We determined in vivo efficacy and target PK/PD exposures of antofloxacin against Streptococcus pneumoniae and Staphylococcus aureus in the murine pneumonia model. The mean plasma free drug area under the concentration-time curve/MIC (fAUC/MIC) targets associated with stasis and 1-log10 and 2-log10 kill effects were 8.93, 19.2, and 48.1, respectively, for S. pneumoniae, whereas they were 30.5, 55.4, and 115.8, respectively, for S. aureus The fAUC/MIC targets in murine lung epithelial lining fluids (ELF) for the same endpoints were nearly 2-fold higher than those in plasma.

Relationship between antofloxacin concentration and QT prolongation and estimation of the possible false-positive rate.

PURPOSE: To elucidate the relationship between antofloxacin (AT) plasma concentration and QT interval prolongation, compare the effects of different correction and analytical methods on conclusions, and estimate the possible false-positive rate in thorough QT (TQT) studies. METHODS: Twenty-four healthy Chinese volunteers from a four-period crossover TQT study orally received 200 mg/d AT, 400 mg/d AT, 400 mg/d moxifloxacin, and a placebo in a random order for 5 d for each. QT interval samples were collected on d 1 and d 5. Population models were established describing the relationship between QT and AT concentration. The yardstick from ICH E14 guidelines was used to measure the effect of drugs on QT prolongation both in biostatistical and modeling analyses. A possible false-positive rate was estimated by constructing a 1000-time bootstrap to obtain the rate-of-difference values between d 1 and d 5 over 5 ms in the placebo period. RESULTS: In the modeling analysis, the QT prolongation estimate at the mean maximal concentration of AT (4.51 µg/mL) was 3.84 ms, and its upper bound of the one-sided 95 % CI was 7.04 ms, which showed a negative effect on QT interval prolongation. The estimation for the false-positive rate was 31 % in this study. CONCLUSION: The effect of AT on QT interval prolongation may not have been significant at the dosage of 400 mg. Baseline and placebo adjustments were necessary in TQT studies. Population modeling has demonstrated clear superiority in making full use of data to accurately analyze the relationship between drugs and QT intervals.

In Vivo Bioluminescent Monitoring of Therapeutic Efficacy and Pharmacodynamic Target Assessment of Antofloxacin against Escherichia coli in a Neutropenic Murine Thigh Infection Model.

Antimicrobial resistance among uropathogens has increased the rates of infection-related morbidity and mortality. Antofloxacin is a novel fluoroquinolone with broad-spectrum antibacterial activity against urinary Gram-negative bacilli, such as Escherichia coli This study monitored the in vivo efficacy of antofloxacin using bioluminescent imaging and determined pharmacokinetic (PK)/pharmacodynamic (PD) targets against E. coli isolates in a neutropenic murine thigh infection model. The PK properties were determined after subcutaneous administration of antofloxacin at 2.5, 10, 40, and 160 mg/kg of body weight. Following thigh infection, the mice were treated with 2-fold-increasing doses of antofloxacin from 2.5 to 80 mg/kg administered every 12 h. Efficacy was assessed by quantitative determination of the bacterial burdens in thigh homogenates and was compared with the bioluminescent density. Antofloxacin demonstrated both static and killing endpoints in relation to the initial burden against all study strains. The PK/PD index area under the concentration-time curve (AUC)/MIC correlated well with efficacy (R2 = 0.92), and the dose-response relationship was relatively steep, as observed with escalating doses of antofloxacin. The mean free drug AUC/MIC targets necessary to produce net bacterial stasis and 1-log10 and 2-log10 kill for each isolate were 38.7, 66.1, and 147.0 h, respectively. In vivo bioluminescent imaging showed a rapid decrease in the bioluminescent density at free drug AUC/MIC exposures that exceeded the stasis targets. The integration of these PD targets combined with the results of PK studies with humans will be useful in setting optimal dosing regimens for the treatment of urinary tract infections due to E. coli.

In Vivo Pharmacokinetic and Pharmacodynamic Profiles of Antofloxacin against Klebsiella pneumoniae in a Neutropenic Murine Lung Infection Model.

Antofloxacin is a novel broad-spectrum fluoroquinolone under development for the treatment of infections caused by a diverse group of bacterial species. We explored the pharmacodynamic (PD) profile and targets of antofloxacin against seven Klebsiella pneumoniae isolates by using a neutropenic murine lung infection model. Plasma and bronchopulmonary pharmacokinetic (PK) studies were conducted at single subcutaneous doses of 2.5, 10, 40, and 160 mg/kg of body weight. Mice were infected intratracheally with K. pneumoniae and treated using 2-fold-increasing total doses of antofloxacin ranging from 2.5 to 160 mg/kg/24 h administered in 1, 2, 3, or 4 doses. The Emax Hill equation was used to model the dose-response data. Antofloxacin could penetrate the lung epithelial lining fluid (ELF) with pharmacokinetics similar to those in plasma with linear elimination half-lives over the dose range. All study strains showed a 3-log10 or greater reduction in bacterial burden and prolonged postantibiotic effects (PAEs) ranging from 3.2 to 5.3 h. Dose fractionation response curves were steep, and the free-drug area under the concentration-time curve over 24 h (AUC0-24)/MIC ratio was the PD index most closely linked to efficacy (R2 = 0.96). The mean free-drug AUC0-24/MIC ratios required to achieve net bacterial stasis, a 1-log10 kill, and a 2-log10 kill for each isolate were 52.6, 89.9, and 164.9, respectively. When integrated with human PK data, these PD targets could provide a framework for further optimization of dosing regimens. This could make antofloxacin an attractive option for the treatment of respiratory tract infections involving K. pneumoniae.

Simultaneous quantification of antofloxacin and its major metabolite in human urine by HPLC-MS/MS, and its application to a pharmacokinetic study.

This study presents a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for the simultaneous determination of antofloxacinin and its main metabolite - N-demethylated metabolite (N-DM) - in human urine. Ornidazole was used as the internal standard. This was a clinical urine recovery study, in which 10 healthy Chinese volunteers were intravenously administered a single 200 mg dose of antofloxacin hydrochloride. Compounds were extracted by albumen precipitation, after which samples were isocratically eluted using a Poroshell 120 SB-C18 column, and were analysed using HPLC-MS/MS under electronic spray ionization positive ion mode. The method was successfully applied in a urine pharmacokinetic study of antofloxacinin, with a detection range of 0.02/0.01 to 200/100 µg/mL (for antofioxacin/N-DM).The average percentages of antofioxacin/N-DM measured in urinary excretion frp, 10 volunteers were 54.9 ± 5.7/8.2 ± 2.5% in 120 h duration.

Wild-Type and Non-Wild-Type Mycobacterium tuberculosis MIC Distributions for the Novel Fluoroquinolone Antofloxacin Compared with Those for Ofloxacin, Levofloxacin, and Moxifloxacin.

Antofloxacin (AFX) is a novel fluoroquinolone that has been approved in China for the treatment of infections caused by a variety of bacterial species. We investigated whether it could be repurposed for the treatment of tuberculosis by studying its in vitro activity. We determined the wild-type and non-wild-type MIC ranges for AFX as well as ofloxacin (OFX), levofloxacin (LFX), and moxifloxacin (MFX), using the microplate alamarBlue assay, of 126 clinical Mycobacterium tuberculosis strains from Beijing, China, of which 48 were OFX resistant on the basis of drug susceptibility testing on Löwenstein-Jensen medium. The MIC distributions were correlated with mutations in the quinolone resistance-determining regions of gyrA (Rv0006) and gyrB (Rv0005). Pharmacokinetic/pharmacodynamic (PK/PD) data for AFX were retrieved from the literature. AFX showed lower MIC levels than OFX but higher MIC levels than LFX and MFX on the basis of the tentative epidemiological cutoff values (ECOFFs) determined in this study. All strains with non-wild-type MICs for AFX harbored known resistance mutations that also resulted in non-wild-type MICs for LFX and MFX. Moreover, our data suggested that the current critical concentration of OFX for Löwenstein-Jensen medium that was recently revised by the World Health Organization might be too high, resulting in the misclassification of phenotypically non-wild-type strains with known resistance mutations as wild type. On the basis of our exploratory PK/PD calculations, the current dose of AFX is unlikely to be optimal for the treatment of tuberculosis, but higher doses could be effective.

Preparation of a novel chitosan-microcapsules/starch blend film and the study of its drug-release mechanism.

A novel drug delivery system, chitosan-microcapsules/starch blend film for antofloxacin controlled release, was prepared, and characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (X-RD), thermogravimetry and derivative thermogravimetry (TG/DTG), and scanning electron microscopy (SEM). Following incorporation of the chitosan-microcapsules in the film matrix, the synergistic interactions between these drug-carriers were significant. The thermostability and mechanical properties of the blend film were greatly improved by the incorporation of the microcapsules. The water resistance of the blend film was enhanced by increasing the content of microcapsules, indicating that the microcapsules acted as moisture barriers. After being incorporated, chitosan-microcapsules/starch blend film shows a sustained drug release. The extent of the film degradation and microcapsules swelling in the release system indicated that the drug released of the blend film was pH-sensitive. The blend film exhibited pharmacodynamic efficacy because of the efficient drug releasing.

Effect of C-5 position on the photochemical properties and phototoxicity of antofloxacin and levofloxacin: A stable and transient study.

The photochemistry of two structure-related fluoroquinolones (FQs), antofloxacin (ANT) and levofloxacin (LEV), was studied in aqueous solution using stable and transient methods. The properties for energy transfer and electron transfer of these two FQs were also studied. The transient absorption spectra of FQs were observed, and transient species were assigned. The LEV triplet state ((3)LEV(⁎)) spectra (λmax = 610 nm) were determined, whereas the transient absorption of ANT could not be observed. The decay rate constant of (3)LEV(⁎) via unimolecular attenuation, self-quenching, and quenching by oxygen was 3.2 × 10(5) s(-1), 6.72 × 10(8) M(-1) s(-1), and 1.01 × 10(9) M(-1) s(-1), respectively. A reasonable diagram showing the decay of (1)FQs* consisting of various substituents at the C-5 position was proposed. The phototoxicity of LEV and ANT was investigated and compared. Insertion of an amino group at the C-5 position made ANT relatively photostable and non-phototoxic compared with LEV.

[Treatment of trophic ulsers of different etiology].

The research included 40 patients with chronic trophic ulcers of lower extremities of different etiology (arterial insufficiency - 14 patients, venous insufficiency - 20 patients, diabetic foot syndrome - 6 people). According to the data of prime bacteriological inoculation, the main pathogens were: gram-positive coccus (Staphylococcus spp., Staphylococcus aureus - 75%, Staphylococcus epidermidis - 7,5%) and yeast-like fungi (Candida albicans - 7,5%). Microbial semination in plentiful quantity (more than 106 KOE) was detected at first inoculation in 85% of the patients. The ointment was applied for the patients. After 20 days, the lack of growth and the decrease of contamination level (lower than critical (less than 102 KOE) were noted. A visual analog scale estimated an intensity of pain in patients and it consisted of 39,8% before the treatment, 27,1% - after 10 days, 14,6% - after 20 days. The "Oflomelid" application allowed the reduction of the terms of wound cleansing from nonviable tissues in majority of patients and gained the fast transition from the granulation to epithelization phase. The principle of wound management with the application of ointment "Oflomelid" should be followed in a moist environment. A modern wound dressing must be used after the ointment. This shortened the terms of separate-phase wound repair and decreased the terms of the whole period of trophic ulcers repair in patients with vascular and endocrine pathology.

Different types of copper complexes with the quinolone antimicrobial drugs ofloxacin and norfloxacin: structure, DNA- and albumin-binding.

Three novel copper(II) complexes with the second-generation quinolone antibacterial agents norfloxacin (nfH) and ofloxacin (ofloH) have been synthesized resulting in the complexes [Cu(nfH)(phen)Cl]Cl·5H(2)O (1·5H(2)O), [Cu(nfH)(2)]Cl(2)·6H(2)O (2·6H(2)O) and [Cu(II)(ofloH)(2)][(Cu(I)Cl(2))(2)] (3), respectively. The crystal structures of the complexes have been determined by X-ray crystallography revealing that the quinolones act as bidentate ligands coordinated to Cu(II) atom through the pyridone oxygen and a carboxylato oxygen. UV study of the interaction of the quinolones and the complexes with calf-thymus DNA (CT DNA) has shown that they can bind to CT DNA with [Cu(II)(ofloxacin)(2)][(Cu(I)Cl(2))(2)] exhibiting the highest binding constant to CT DNA. The cyclic voltammograms of the complexes in the presence of CT DNA solution have shown that the interaction of the complexes with CT DNA is mainly through electrostatic binding. DNA solution viscosity measurements have shown that the interaction of the compounds with CT DNA by classical intercalation may be ruled out. Competitive studies with ethidium bromide (EB) indicate that the complexes can partially displace the DNA-bound EB suggesting low to moderate competition with EB. Norfloxacin, ofloxacin and their copper complexes exhibit good binding propensity to human or bovine serum albumin protein having relatively high binding constant values.

Dose findings of antofloxacin hydrochloride for treating bacterial infections in an early clinical trial using PK-PD parameters in healthy volunteers.

AIM: To find an appropriate dose regimen of the novel antibacterial agent antofloxacin for a phase II clinical trial using a population pharmacokinetic (PPK) study in healthy volunteers and the minimum inhibitory concentration (MIC) as pharmacodynamic (PD) parameters. METHODS: Twenty-four healthy volunteers were enrolled in a double-blind crossover study and received antofloxacin (200 or 400 mg/d, po) for consecutive 5 d with 10 d washout between two separate periods. Blood concentrations were analyzed using HPLC with a UV-Vis detector. The values of area under the curve (AUC) with covariates were obtained from a PPK model, and the MICs came from the previous in vitro studies. The dose regimen was determined for the phase II clinical trial according to the ratio (>20) of AUC/MIC, and the efficacy of the dose was evaluated by the trial. RESULTS: A two-compartment model best described the time-concentration data with first-order absorption. The PPK parameter estimates for CL, V(c), Q, V(p) and K(A) are 8.34 L/h, 142 L, 15.9 L/h, 52.2 L and 4.64 1/h, respectively. The covariates sex for K(A), weight for CL, weight for V(c) and interoccasion variability were included in the final model. The AUC/MIC was calculated based on the PPK model and the MIC of antofloxacin for Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus and Staphylococcus epidermidis were determined in previous researches. The 400 mg loading dose with 200 mg/d maintenance dose was recommended and confirmed by the phase II trial. CONCLUSION: The ratio of AUC from the PPK model vs MIC as the PD parameter can be applied in a dose-finding trial of antofloxacin in treatment of bacterial infections. The PPK model suggests that sex and body weight may be considerations in regards to individual therapy, which should be investigated in larger clinical trials and serve as a potential reference for clinical therapies.

Synthesis of lipophilic dimeric C-7/C-7-linked ciprofloxacin and C-6/C-6-linked levofloxacin derivatives. Versatile in vitro biological evaluations of monomeric and dimeric fluoroquinolone derivatives as potential antitumor, antibacterial or antimycobacterial agents.

The synthesis of C-7/C-7-linked ciprofloxacin (CP) and C-6/C-6-linked levofloxacin (LV) derivatives with modulated lipophilicity is described herein. The synthesized compounds, along with the monomeric analogs described previously, were evaluated in vitro for (i) their growth inhibitory effect against five human cancer cell lines, (ii) their antibacterial activity against Gram-positive Staphylococcus aureus and Enterococcus hirae and Gram-negative Escherichia coli and Pseudomonas aeruginosa strains and (iii) their antimycobacterial activity. The most efficient derivatives as antiproliferative agents (C-7/C-7-linked CP 7e and C-6/C-6-linked LV 11f) displayed IC(50) values in the 0.1-8.7 and 0.2-0.7 µM ranges respectively while IC(50) values for parent CP and LV ranged from 89 to 476 µM and from 67 to 622 µM respectively depending on the cell line. A specific antibacterial activity against S. aureus was found for the monomeric and dimeric derivatives of CP. The most efficient derivative against S. aureus (monomeric oxoethyloctanoate CP derivative 3d) displayed MIC <1 nM. Monomeric alkanoyloxymethyl LV esters (9a,c,e,f) and C-6/C-6-linked LV derivatives (11f-h) were the most efficient derivatives as antimycobacterial agents with MIC and IC(50) values in the 2.5-5 µM and 1.3-≤ 2.5 µM ranges respectively while MIC and IC(50) values for parent LV were 2.5 and 0.8 µM, respectively.

Modulation of pharmacokinetics of theophylline by antofloxacin, a novel 8-amino-fluoroquinolone, in humans.

AIM: To evaluate the pharmacokinetic interactions between theophylline and antofloxacin in vivo and in vitro. METHODS: A randomized, 5-day treatment and 3-way crossover design was documented in 12 healthy subjects. The subjects were orally administered with antofloxacin (400 mg on d 1 and 200 mg on d 2 to 5), theophylline (100 mg twice a day and morning dose 200 mg on d 1 and 5), or theophylline plus antofloxacin. The plasma and urinary pharmacokinetics of antofloxacin and theophylline were characterized after the first and last dose. The effect of antofloxacin on theophylline metabolism was also investigated in pooled human liver microsomes. RESULTS: The 5-day treatment with antofloxacin significantly increased the area of the plasma concentration-time curve and peak plasma concentration of theophylline, accompanied by a decrease in the excretion of theophylline metabolites. On the contrary, theophylline did not affect the pharmacokinetics of antofloxacin. In vitro studies using pooled human hepatic microsomes demonstrated that antofloxacin was a weak reversible and mechanism-based inhibitor of CYP1A2. The clinical interaction between theophylline and antofloxacin was further validated by the in vitro results. CONCLUSION: The results showed that antofloxacin increases the plasma theophylline concentration, partly by acting as a mechanism-based inhibitor of CYP1A2.

[A multi-center, randomized, controlled, double blind and double dummy clinical trial of antofloxacin hydrochloride tablet versus levofloxacin tablet for the treatment of acute bacterial infections].

OBJECTIVE: To evaluate the clinical efficacy and safety of antofloxacin hydrochloride tablet for the treatment of acute bacterial infections. METHODS: A multi-center randomized control, double blind and double dummy clinical trial was conducted; levofloxacin tablet was closed as controlled drug. The duration of treatment was 7-14 days in both groups. RESULTS: A total of 719 patients were enrolled in the study, in which 359 patients treated with antofloxacin and 360 patients treated with levofloxacin were included. Three hundred and thirty and 337 patients completed the study and met with all the criteria for per-protocol analysis, respectively. By the end of chemotherapy, the cured rates in per protocol set (PPS) population were 79.7% and 77.4%, the effective rates were 95.2% and 96.7%, and the bacterial clearance were 96.7% and 97.5% for the treating and control group, respectively. The clinical and bacterial efficacy of antofloxacin and levofloxacin was comparable by the analysis of infectious sites. Three hundred and fifty-seven and 356 patients in antofloxacin and levofloxacin groups were evaluated the safety. The drug adverse events occurred both in 10.1%, and drug adverse reactions occurred in 7.8% and 7.9% patients in the two groups. The most common drug adverse reactions were mild gastroenteric symptoms. No QTc prolongation was detected in all the patients. One patient in each group had mild blood glucose increase at the end of therapy, but the glucose returned to normal level without any intervention. No statistic significant difference between the two groups in clinical efficacy and safety was detected (P > 0.05). CONCLUSIONS: Antofloxacin hydrochloride tablet was effective and safe for the treatment of acute bacterial infections.

A physiologically based pharmacokinetic model characterizing mechanism-based inhibition of CYP1A2 for predicting theophylline/antofloxacin interaction in both rats and humans.

Clinical studies have revealed that some fluoroquinolones may cause severe adverse effects when co-administered with substrates of CYP1A2. Our previous study showed antofloxacin (ATFX) was responsible for mechanism-based inhibition (MBI) of the metabolism of phenacetin in rats. In the clinical setting, ATFX is likely to be administrated with theophylline (TP), which is mainly metabolized by CYP1A2. The aim of the present study was to investigate the possible mechanism of TP/ATFX interaction. In vitro studies showed that the inhibitory effect of ATFX on the formation of three TP metabolites depended on NADPH, the pre-inhibition time, and ATFX concentration, i.e., factors which characterize MBI. In vivo studies demonstrated that single-dose ATFX (20 mg/kg) did not affect the pharmacokinetic behavior of TP, but multidose ATFX (20 mg/kg b.i.d. for 7.5 days) significantly increased the AUC of TP, decreased the amount of three TP metabolites in urine, and suppressed hepatic microsomal activity. A physiologically based pharmacokinetic (PBPK) model characterizing MBI of the three TP metabolites was developed for predicting TP/ATFX interaction in rats; this model was further extrapolated to humans. The predicted results were in good agreement with observed data. All the results indicated that ATFX was responsible for MBI of the metabolism of TP, and the PBPK model characterizing MBI may give good prediction of TP/ATFX interaction.

Pharmacokinetic study of single and multiple oral dose administration of antofloxacin hydrochloride in healthy male volunteers.

BACKGROUND: A new fluroquinolone antibacterial agent, antofloxacin hydrochloride, developed in China, is an 8-NH(2) derivant of levofloxacin. The purpose of the study was to evaluate the pharmacokinetic characteristics of single and multiple oral doses of antofloxacin hydrochloride in Chinese healthy male volunteers. METHODS: An open-label, non-randomized, single and multiple dose clinical trial was conducted. In single dose study, 12 subjects took 200 mg antofloxacin hydrochloride. In multiple dose study, 12 subjects took antofloxacin hydrochloride 400 mg once on day 1 and 200 mg once daily from day 2 to day 7. HPLC was used to assay the serum and urinary concentrations of antofloxacin. RESULTS: In single dose study, the maximum concentration of drug in serum (C(max)), the time to reach C(max) (T(max)), and the area under the serum concentration-time curve (AUC (0-∞)) of antofloxacin were (1.89 ± 0.65) mg/L, (1.29 ± 0.26) hours, and (25.24 ± 7.26) mg×h(-1)×L(-1), respectively. Accumulating elimination rate of antoflocaxin from urine within 120 hours was 39.1%. In multiple dose study, blood concentration of antofloxiacin achieved stable state on day 2 after dosing. The minimum concentration drug in serum (C(min)), AUCss, mean concentration of drug in serum (C(av)), and degree of fluctuation (DF) were (0.73 ± 0.18) mg/L, (47.59 ± 7.85) mg×h(-1)×L(-1), (1.98 ± 0.33) mg/L, and 1.74 ± 0.60, respectively. On day 7 after dosing, T(max), C(max), and AUC (0-∞) was (1.14 ± 0.50) hours, (2.52 ± 0.38) mg/L, and (48.77 ± 8.44) mg×h(-1)×L(-1), respectively. Accumulating elimination rate of antofloxaxin from urine within 120 hours after the last dosing was 60.06%. CONCLUSIONS: The regimen of 400 mg loading dose given on the first treatment day and then 200 mg dose once daily results in satisfactory serum drug concentration.

Pharmacokinetics of antofloxacin hydrochloride in healthy male subjects after multiple intravenous dose administration.

The purpose of the study was to evaluate pharmacokinetic characteristics of antofloxacin hydrochloride, a new fluoroquinolone antibiotic, during a multiple, intravenous dosing regimen. Twelve healthy, Chinese male volunteer subjects were each given 300 mg of antofloxacin by intravenous infusion once daily for 7 days. Blood and urine samples were taken at designated time points for analysis of antofloxacin concentration by high-performance liquid chromatography (HPLC). Safety and tolerability were assessed by evaluation of subject complaints, vital signs, electrocardiograms, electroencephalograms, clinical chemistry parameters, haematology and urinalysis and prothrombin time. The serum steady concentration of antofloxacin was obtained in 96 h after the administration of a daily intravenous dose of 300 mg of the drug. In the present study, the following pharmacokinetic parameters after 7 days of treatment with antofloxacin were determined to be: C(max) 3.81 ± 0.66 mg/L, C(min) 0.85 ± 0.19 mg/L, AUC(0-24) 60.51 ± 8.30 mg/L·h, C(av) 2.52 ± 0.35 mg/L, PTF 87.45 ± 3.37%, t(1/2)ß 20.34 ± 1.88 h. The C(max) and AUC(0-24) after 7-day treatment were both higher than after the first dose (by 43% and 110%, respectively). The cumulative urinary elimination of antofloxacin within 96 h after the last dose was about 56%. During the study, there were neither subject complaints nor significant adverse clinical findings. Antofloxacin, administered intravenously as a single, daily 300 mg dose for 7 days, demonstrated favourable pharmacokinetic characteristics and tolerability. The results of this study indicate that antofloxacin hydrochloride is suitable for further clinical study.

Synthesis, characterization and biological activity of a series of carboxamide derivatives of ofloxacin.

The present study was designed to help develop new agents with better antimicrobial profiles. Specifically, we focused on modification of the basic structure of ofloxacin by introducing new functionality at its C3 position. For this purpose, the carboxylic group at the C3 position of ofloxacin was replaced by an amide group through an ester aminolysis reaction. The structure of these derivatives was established by various analytical techniques i.e., IR, (1)H-NMR, (13)C-NMR CHNS elemental analysis and mass spectrometry. The antibacterial activity of ofloxacin and its derivatives against ten different Gram-positive and Gram-negative microorganisms was studied using a disk susceptibility method. These compounds were further tested for their activity against various fungi and compared to ofloxacin. The synthesized compounds showed diverse antimicrobial profiles. Among them, a few compounds possessed a comparable or better activity in comparison to the reference drug.