Ln-MOF-Based Hydrogel Films with Tunable Luminescence and Afterglow Behavior for Visual Detection of Ofloxacin and Anti-Counterfeiting Applications.

Highly selective and sensitive quantitative detection of ofloxacin (OFX) at ultralow concentrations in aqueous media and development of new afterglow materials remains a challenge. Herein, a new 2D water-stable lanthanide metal-organic framework (NIIC-2-Tb) is proposed, which exhibits high selectivity towards OFX through the luminescence quenching with the lowest detection limit (1.1 × 10-9 M) reported to date and a fast response within 6 s. In addition, the luminescent detection of OFX by NIIC-2-Tb is not affected by typical components of blood plasma and urine. The excellent sensing effect of NIIC-2-Tb is further utilized to prepare a composite functional sensing carrageenan hydrogel material for the rapid detection of OFX in meat in real time and the first discovery of impressive afterglow in MOF-based hydrogels. This study not only presents novel Ln-MOF materials and Ln-MOF-based hydrogel films for luminescent sensing of OFX, but also demonstrates color-tunable luminescent films with afterglow, which expands the application of composite luminescent materials for detection and anti-counterfeiting.

Antibiotic burden of school children from Tibetan, Hui, and Han groups in the Qinghai-Tibetan Plateau.

BACKGROUND: Given their geographical proximity but differences in cultural and religious dietary customs, we hypothesize that children from the three main ethnic populations (Han, Hui, and Tibetan) residing in the Qinghai-Tibetan Plateau region differs in their non-iatrogenic antibiotic loads. METHODS: To determine the antibiotic burden of the school children unrelated to medical treatment, we quantified the antibiotic residues in morning urine samples from 92 Han, 72 Tibetan, and 85 Muslim Hui primary school children aged 8 to 12 years using high-performance liquid chromatography-tandem mass spectrometry, and performed correlation analysis between these data and concurrent dietary nutrition assessments. RESULTS: Sixteen of the 18 targeted antibiotics (4 macrolides, 3 ß-lactams, 2 tetracyclines, 4 quinolones, 3 sulfonamides, and 2 aminoanols) were identified in the urine samples with an overall detection frequency of 58.63%. The detection frequency of the six antibiotic classes ranged from 1.61% to 32.53% with ofloxacin showing the single highest frequency (18.47%). Paired comparison analysis revealed significant differences in antibiotic distribution frequency among groups, with Tibetans having higher enrofloxacin (P = 0.015) and oxytetracycline (P = 0.021) than Han children. Norfloxacin (a human/veterinary antibiotic) was significantly higher in the Hui children than in the Han children (P = 0.024). Dietary nutrient intake assessments were comparable among participants, showing adequate levels of essential vitamins and minerals across all three ethnic groups. However, significant differences in specific foods were observed among groups, notably in lower fat consumption in the Hui group. CONCLUSIONS: The introduction and accumulation of antibiotic residues in school children through non-iatrogenic routes (food or environmental sources) poses a serious potential health risk and merits closer scrutiny to determine the sources. While the exact sources of misused or overused antibiotics remains unclear, further study can potentially correlate ethnicity-specific dietary practices with the sources of contamination.

Simultaneous voltammetric sensing of levodopa, piroxicam, ofloxacin and methocarbamol using a carbon paste electrode modified with graphite oxide and ß-cyclodextrin.

A carbon paste electrode (CPE) was modified with graphite oxide (GrO) and ß-cyclodextrin (CD) to obtain a sensor for simultaneous voltammetric determination of levodopa (LD), piroxicam (PRX), ofloxacin (OFX) and methocarbamol (MCB). The morphology, structure and electrochemical properties of the functionalized GrO were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, contact angle measurements and cyclic voltammetry. Under the optimal experimental conditions, the sensor is capable of detecting LD, PRX, OFX and MCB by square wave voltammetry (SWV) at working potentials of +0.40, +0.60, +1.03 and + 1.27 V (versus Ag/AgCl), respectively. Response is linear from 1.0 to 20 µM for LD, from 1.0 to 15 µM for PRX, from 1.0 to 20 µM for OFX, and from 1.0 to 50 µM for MCB. The respective limits of detection are 65, 105, 89 and 400 nM. The method was successfully applied to the simultaneous determination of LD, PRX, OFX and MCB in (spiked) real river water and synthetic urine samples, and the results were in agreement with those obtained using a spectrophotometric method, with recoveries close to 100%. Graphical abstract Schematic presentation of a novel electroanalytical method employing a carbon paste electrode modified with graphite oxide and ß-cyclodextrin for the simultaneous determination of levodopa, piroxicam, ofloxacin and methocarbamol in urine and river water samples by square wave voltammetry.

A rotating cotton-based disk packed with a cation-exchange resin: Separation of ofloxacin from biological fluids followed by chemiluminescence determination.

A novel approach for green and simple solid-phase extraction of ionizable analytes using cation-exchange resin particles packed in a rotating cotton-based disk has been developed and utilized for the chemiluminescence determination of ofloxacin in biological fluids (serum and urine). The use of highly-available cation-exchange resin provided effective separation of analyte from complex sample matrixes and its elution by aqueous electrolyte solution without any organic solvents. Ofloxacin ionization in acidic sample solution allowed to provide effective separation of the analyte for subsequent chemiluminescence detection. The cotton-based disk was characterized by effective wettability. This feature promoted high mass transfer of the analyte to the cation-exchange resin surface at separation step and into elution solution at elution step. The sorption time was decreased to 10 min while the elution time was 5 min. Under the optimal conditions, the detector response for ofloxacin was linear in the concentration range from 9 × 10-8 to 3 × 10-5 mol L-1. The limit of detection, calculated from a blank test based on 3σ, was 3 × 10-8 mol L-1.

Enantioseparation and sensitive analysis of ofloxacin by poly(3,4-dihydroxyphenylalanine) functionalized magnetic nanoparticles-based solid phase extraction in combination with on-line concentration capillary electrophoresis.

Chiral separation of low concentrations of pharmaceuticals in biofluids is a challenge task. In this study, a method is developed to enantioseparate trace amount of racemic ofloxacin in urine and bovine blood by combining magnetic solid phase extraction (MSPE) and chiral capillary electrophoresis (CE). Poly(3,4-dihydroxyphenylalanine) modified magnetic nanoparticles (polyDOPA-MNPs) are prepared and used as the adsorbents in MSPE to extract ofloxacin. The polyDOPA-MNPs are spherical, about 130 nm in diameter and the polyDOPA shell is about 3 nm. The extraction process of polyDOPA-MNPs for ofloxacin includes 2 min adsorption and 2 min desorption with the assistance of sonication. Under the optimized MSPE conditions (3 mg polyDOPA-MNPs as adsorbents, sample pH 7.0, 75% (v/v) AcOH in methanol as eluent, adsorption time 2 min, desorption time 2 min), the extraction efficiency of ofloxacin is 95%. In chiral CE, pressure-assisted field-enhanced sample injection (PA-FESI) is developed to improve the detection sensitivity of ofloxacin enantiomers. The MSPE/PA-FESI chiral CE method demonstrates a good linearity in the concentration range of 0.01-0.06 µg/mL, with a detection limit as low as 0.29 ng/mL. The feasibility of the method is verified by the successful determination of trace amounts of ofloxacin enantiomers in spiked urine and bovine blood samples.

The urinary excretion of metformin, ceftizoxime and ofloxacin in high serum creatinine rats: Can creatinine predict renal tubular elimination?

The renal excretion of creatinine and most drugs are the net result of glomerular filtration and tubular secretion, and their tubular secretions are mediated by individual transporters. Thus, we hypothesized that the increase of serum creatinine (SCr) levels attributing to inhibiting tubular transporters but not glomerular filtration rate (GFR) could be used to evaluate the tubular excretion of drugs mediated by identical or partial overlap transporter with creatinine. In this work, we firstly developed the creatinine excretion inhibition model with normal GFR by competitively inhibiting tubular transporters, and investigated the renal excretion of metformin, ceftizoxime and ofloxacin in vivo and in vitro. The results showed that the 24-hour urinary excretion of metformin and ceftizoxime in model rats were decreased by 25% and 17% compared to that in control rats, respectively. The uptake amount and urinary excretion of metformin and ceftizoxime could be inhibited by creatinine in renal cortical slices and isolated kidney perfusion. However, the urinary excretion of ofloxacin was not affected by high SCr. These results showed that the inhibition of tubular creatinine transporters by high SCr resulted to the decrease of urinary excretion of metformin and ceftizoxime, but not ofloxacin, which implied that the increase of SCr could also be used to evaluate the tubular excretion of drugs mediated by identical or partial overlap transporter with creatinine in normal GFR rats.

Fabrication of magnetic Fe3O4@nSiO2@mSiO2-NH2 core-shell mesoporous nanocomposite and its application for highly efficient ultrasound assisted dispersive µSPE-spectrofluorimetric detection of ofloxacin in urine and plasma samples.

In this research, a sensitive, simple and rapid ultrasound assisted dispersive micro solid-phase extraction (USAD-µSPE) was developed using a synthesized core-shell magnetic mesoporous nanocomposite (Fe3O4@nSiO2@mSiO2-NH2) as an efficient adsorbent for the preconcentration and spectrofluorometric determination of ofloxacin (OFL) in biological samples. The synthesized adsorbent was characterized using FT-IR spectroscopy, transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), energy dispersive X-ray (EDX) spectroscopy, thermogravimetric analysis (TGA) and Brunauer-Emmett-Teller (BET) analysis. The application of this magnetic nanocomposite as a sensitive solid phase for removal, preconcentration and spectrofluorometric quantification of trace amount of OFL was developed. Influence of various variables including pH, sorbent dosage, desorption solvent properties and sonication time on present method response was studied and optimized. The results showed that using the proposed method OFL can be determined in the linear concentration range of 1.0-500.0µgL-1 with a limit of detection as low as 0.21µgL-1 and relative standard deviation less than 2.5 (%). The results of human urine and blood plasma analysis showed that the method is a good candidate for biological sample analysis purposes.

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.

A fully automated effervescence-assisted switchable solvent-based liquid phase microextraction procedure: Liquid chromatographic determination of ofloxacin in human urine samples.

A novel fully automated effervescence-assisted switchable solvent-based liquid phase microextraction procedure has been suggested. In this extraction method, medium-chain saturated fatty acids were investigated as switchable hydrophilicity solvents. The conversion of fatty acid into hydrophilic form was carried out in the presence of sodium carbonate. The injection of sulfuric acid into the solution decreased the pH value of the solution, thus, microdroplets of the fatty acid were generated. Carbon dioxide bubbles were generated in-situ, and promoted the extraction process and final phase separation. The performance of the suggested approach was demonstrated by the determination of ofloxacin in human urine samples using high-performance liquid chromatography with fluorescence detection. This analytical task was used as a proof-of-concept example. Under the optimal conditions, the detector response of ofloxacin was linear in the concentration ranges of 3·10(-8)-3·10(-6) mol L(-1). The limit of detection, calculated from a blank test based on 3σ, was 1·10(-8) mol L(-1). The results demonstrated that the presented approach is highly cost-effective, simple, rapid and environmentally friendly.

In-tube magnetic solid phase microextraction of some fluoroquinolones based on the use of sodium dodecyl sulfate coated Fe3O4 nanoparticles packed tube.

In-tube magnetic solid phase microextraction (in-tube MSPME) of fluoroquinolones from water and urine samples based on the use of sodium dodecyl sulfate (SDS) coated Fe3O4 nanoparticles packed tube has been reported. After the preparation of Fe3O4 nanoparticles (NPs) by a batch synthesis, these NPs were introduced into a stainless steel tube by a syringe and then a strong magnet was placed around the tube, so that the Fe3O4 NPs were remained in the tube and the tube was used in the in-tube SPME-HPLC/UV for the analysis of fluoroquinolones in water and urine samples. Plackett-Burman design was employed for screening the variables significantly affecting the extraction efficiency. Then, the significant factors were more investigated by Box-Behnken design. Calibration curves were linear (R(2)>0.990) in the range of 0.1-1000µgL(-1) for ciprofloxacin (CIP) and 0.5-500µgL(-1) for enrofloxacin (ENR) and ofloxacin (OFL), respectively. LODs for all studied fluoroquinolones ranged from 0.01 to 0.05µgL(-1). The main advantages of this method were rapid and easy automation and analysis, short extraction time, high sensitivity, possibility of fully sorbent collection after analysis, wide linear range and no need to organic solvents in extraction.

Ofloxacin determination in urine, serum and pharmaceuticals using an automatic flow potentiometric system.

An automatic system was developed to determine ofloxacin in biological fluids and pharmaceutical formulations. Drug detection was carried out by a potentiometric membrane sensor based on [bis(trifluoromethyl)phenyl]borate as molecular-recognition material. The tubular shaped detector system was solidly attached to the manifold, creating a high-throughput stable setup (50 samples per hour) appropriate for routine antibiotic assessment. Under the optimized flow conditions, the sensor displayed a mean detection limit of 1 × 10(-5) M, a linear response over the concentrations of 2 × 10(-5) to 5 × 10(-3) M (slope of 57.4 mV decade(-1)) and a wide working pH range (2.1 - 6.6). The procedure was successfully applied to ofloxacin analysis in pharmaceuticals (relative deviation lower than 6%) and biological fluids at levels usually found after drug administration of clinical doses (recoveries between 91 and 106%). No significant interference from common excipients found in commercial formulations and inorganic ions usually present in biological fluids was noticed.

Development of a spectrofluorimetric method for the determination of ofloxacin in urine.

A simple, accurate, rapid, and sensitive spectrofluorimetric method for the determination of ofloxacin in urine was developed by means of first derivative matrix isopotential synchronous fluorescence spectrometry (MISF). The calibration curve was found to be linear in the concentration range 40-320 ng/mL. The method allows the determination of compound in samples with unknown background fluorescence without the need for tedious pre-separation. Synchronous scans are performed along a trajectory that connects points of identical intensity in a three-dimensional fluorescence spectrum. The unknown analytical signal of the urine is suppressed from the MISF spectrum by calculating its first derivative at λex = 319.2 and λem = 465 nm. In order to ensure maximum sensitivity and adequate selectivity, the experimental variables affecting fluorescence intensity were studied in the ofloxacin band centered at λex = 333 and λem = 460 nm. As result, the determination was performed in a water medium at pH 7.2, adjusted by using sodium dihydrogen phosphate as a buffer solution. Calibration graphs were subjected to a comprehensive statistical analysis. The detection limit according to Long and Winefordner was 8.4 ng/mL, and the detection limit proposed by Clayton was 13.9 ng/mL.

Pharmacokinetics, urinary excretion and plasma protein binding of ofloxacin in water buffalo calves (Bubalus bubalis).

Pharmacokinetics and urinary excretion of an intravenous dose of 5 mg.kg-1 ofloxacin were investigated in water buffalo calves. Plasma concentrations of ofloxacin were determined by high-performance liquid chromatography. Ofloxacin was rapidly distributed from the central to the peripheral compartment as evidenced by a short distribution half-life (0.09 h ± 0.003 h) and high K12 (4.7 h(-1) ± 0.1 h(-1)), and was detected in plasma for 8 h. The large volume of distribution (2.48 L.kg(-1) ± 0.18 L.kg(-1)) obtained in this study indicated high distribution of ofloxacin in water buffalo calves. The elimination half-life, the area under the plasma drug concentration-time curve and total body clearance were 2.11 h ± 0.13 h, 6.20 µg.mL(-1) ± 0.23 µg.mL(-1).h and 0.81 mL.kg(-1).h(-1) ± 0.03 mL.kg(-1).h(-1), respectively. About 18.7% of administered drug was bound to plasma proteins and approximately 32.5% of the administered dose was recovered in urine within 48 h. The results of the study indicated a favourable pharmacokinetic profile of ofloxacin in water buffalo calves, which suggests that ofloxacin may be effective against urinary pathogens in this species.

Simultaneous determination of the combined drugs of ceftriaxone sodium, metronidazole, and levofloxacin in human urine by high-performance liquid chromatography.

AIM: To develop a new high-performance liquid chromatography (HPLC) method for simultaneous determination of the combined drugs (ceftriaxone sodium, metronidazole, and levofloxacin) in human urine. METHODS: Ceftriaxone sodium, metronidazole, and levofloxacin were separated on a Kromasil 100-5 C18 (250 mm × 4.6 mm, 5 µm, AKZO NOBEL, Bohus, Sweden) analytical column, using the mobile phase consisted of 1.5 mM KH(2) PO(4) (pH 4.5) with 0.0125% triethylamine-methnol (70:30, v/v). Ceftriaxone sodium, metronidazole, and levofloxacin were detected by a photodiode-array detector at 247, 320, 292 nm, respectively. RESULTS: Under optimal conditions, the effective separation of ceftriaxone sodium, metronidazole, and levofloxacin was achieved. A good linearity with the correlation coefficients more than 0.999 was demonstrated. The detection limits of ceftriaxone sodium, metronidazole, and levofloxacin were 0.05, 0.01, and 0.25 µg/ml, respectively, and the average recoveries in human urine were in the range from 97.73 to 100.7% with the average relative standard deviation (RSD) in the range of 2.5% and 3.0%. CONCLUSION: The proposed method was sensitive, accurate, and rapid. This work may provide a reference for clinical rational drug use and methodology for the pharmacokinetics study of the combined drugs.

Application of non-linear angle synchronous spectrofluorimetry to the determination of complex mixtures of drugs in urine: a comparative study.

Synchronous fluorescence spectroscopy (SFS) is a rapid, sensitive and non-destructive method suitable for the analysis of multifluorophoric mixtures. In this study non linear variable angle synchronous spectrofluorimetry was applied to the determination of three fluoroquinololes in urine. Although this technique provides very good results, total resolution of multicomponent mixtures is not always achieved when the spectral profiles strongly overlap. Partial least-squares regression (PLS-1) was utilized to a develop calibration model that related synchronous fluorescence spectra to the analytical concentration of fluoroquinolones in the presence of urine. The same multicomponent mixture was determined using excitation emission matrix fluorescence (EEMF) along with N-way partial least squares regression (N-PLS and U-PLS). The determination was carried out in micellar medium 0.01 M with a pH of 4.8 provided by 0.2 M sodium acetate/acetic acid buffer. A central composite design was selected to obtain a calibration matrix of 25 standards plus a blank sample. The proposed methods were validated by application to a test set of synthetic samples. The results show that SFS with PLS-1 is a better method compared to EEMF with N-PLS or U-PLS because of the low RMSEP values of the former.

Pharmacokinetic variation of ofloxacin based on gender-related difference in the expression of multidrug resistance-associated protein (Abcc2/Mrp2) in rat kidney.

The present study aimed to investigate the pharmacokinetic variation of ofloxacin based on gender-related difference in the expression of multidrug resistance-associated protein (Abcc2/Mrp2) in rat kidney. The concentrations of ofloxacin in rat plasma and urine were determined after tail vein administration (30 mg x kg(-1)) by high-performance liquid chromatography (HPLC) method. Expression of Mrp2 in kidney of male and female rats was qualitatively and quantitatively detected by immunohistochemistry and flow cytometry, separately. The results showed that AUC value of ofloxacin was lower in male rats than that in female rats and the total amount of ofloxacin excreted in the urine was higher in male rats than that in female rats. And the expression of Mrp2 in male rat kidney was higher than that in female rats. All results suggested that gender-related differences in pharmacokinetics of ofloxacin may be attributed to the differences in the expression of Mrp2 in kidney of male and female rats.

Method validation and determinations of levofloxacin, metronidazole and sulfamethoxazole in an aqueous pharmaceutical, urine and blood plasma samples using quantitative nuclear magnetic resonance spectrometry.

Selective, rapid and accurate quantitative proton nuclear magnetic resonance (qHNMR) method for the determination of levofloxacin, metronidazole benzoate and sulfamethoxazole in aqueous solutions was developed and validated. The method was successfully applied to the determinations of the drugs and their admixtures in pharmaceutical, urine and plasma samples. Maleic acid and sodium malate were used as internal standards. Effect of temperature on spectral measurements was evaluated. Linear dynamic ranges of 0.50-68.00, 0.13-11.30 and 0.24-21.00 mg per 0.60 mL solution were obtained for levofloxacin, metronidazole benzoate and sulfamethoxazole, respectively. Average recovery % in the range of 96.00-104.20 ± (0.17-2.91) was obtained for drugs in pure, pharmaceutical, plasma and urine samples. Inter and intra-day analyses gave average recoveries % in the ranges 96.10-98.40 ± (1.68-2.81) and 96.00-104.20 ± (0.17-2.91), respectively. Instrumental detection limits ≤0.03 mg per 0.6 mL were obtained for the three drugs. Developed method has demonstrated high performance characteristics for analyzing investigated drugs and their admixtures. Student t-test at 95% confidence level revealed insignificant bias between the real and measured contents of investigated drugs in pure, pharmaceutical, urine and plasma samples and its admixtures. Application of the statistical F-test revealed insignificant differences in precisions between the developed method and arbitrary selected reference methods.

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.

Chemiluminescence determination of fluoroquinolones using Fenton system in the presence of terbium(iii) ions.

A simple new chemiluminescent, CL, method is described for the determination of fluoroquinolones such as: ciprofloxacin (CF), norfloxacin (NF), and ofloxacin (OF). This method is based on the measurement of terbium(iii) emission. This emission follows an energy transfer to the uncomplexed terbium(iii) ions from the excited products of fluoroquinolone oxidations. Under optimum conditions, calibration graphs were obtained for 2 × 10(-8)-2 × 10(-6) mol L(-1) of NF; 3 × 10(-8)-2 × 10(-6) mol L(-1) of CF and 4 × 10(-7)-5 × 10(-5) mol L(-1) of OF. The detection limits are 7 × 10(-9) mol L(-1) norfloxacin, 1 × 10(-8) mol L(-1) ciprofloxacin and 1.5 × 10(-7) mol L(-1) ofloxacin. The method was successfully applied to the determination of these drugs in pharmaceutical formulations.

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.