Concentrations Of Gatifloxacin Research Articles

Comparative Study of Ocular Pharmacokinetics of Topical 0.3% Gatifloxacin Eye Gel and Solution in Rabbits.

Few articles have reported drug concentrations of different ophthalmic dosage forms in the ocular tissues. This study aimed to determine the ocular pharmacokinetics of gatifloxacin 0.3% eye gel (GTX-Gel) and gatifloxacin 0.3% eye solution (GTX-Sol) at different time intervals after topical instillation in rabbits. A total of 126 healthy New Zealand rabbits were included, of which six rabbits did not receive antibiotics (control group). The remaining rabbits were randomly divided into four groups. GTX-Gel and GTX-Sol (50 μL) were topically instilled every hour in groups A1 and B1, respectively, and every two hours in groups A2 and B2, respectively, for 12 h. Ocular tissues were collected 2, 4, 8, 12, and 24 h after administration. Gatifloxacin concentration was measured using high-performance liquid chromatography coupled with tandem mass spectrometry. The drug reached peak concentrations (Cmax) in all tissues at 8–12 h. With the same administration frequency, the Cmax was higher with GTX-Gel than with GTX-Sol (p < 0.05). Except for the iris-ciliary body, other ocular tissues did not show significant difference (p > 0.05) in gatifloxacin concentration between either pair of groups. Gatifloxacin ophthalmic gel was found to attain significantly higher concentrations than the ophthalmic solution in ocular tissues.

Antimicrobial Effects of Gatifloxacin on Canine Periodontopathic Bacteria &amp;lt;i&amp;gt;In Vitro&amp;lt;/i&amp;gt;

The aim of this study was to identify the potential antibacterial effects of gatifloxacin on one of canine periodontal pathogens, Porphyromonas gulae. The minimum inhibitory concentrations (MIC) of gatifloxacin and its bactericidal effects were investigated. Gatifloxacin inhibited the growth of the canine periodontopathic bacteria tested in broth. An MIC of 50 nM was found to be effective in inhibiting P. gulae. On performing adenosine triphosphate bioluminescence assay, gatifloxacin was found to exhibit bactericidal effects on the tested bacteria in a concentration-dependent manner. The safety of gatifloxacin in mammalian cells was evaluated by assessing the viability of rat bone marrow mesenchymal stem (BMMS) cells treated with gatifloxacin. Almost over 80% of BMMS cells survived after a 3-day culture when treated with 100 nM of gatifloxacin. These results indicate that locally administered gatifloxacin has the potential for being used to prevent canine periodontal infection.

Swelling Behaviour and Water Vapour Transmission Rates of Gellan Gum/Collagen Film Containing Gatifloxacin as Dressing Materials

In an effort to produce ideal wound dressing, gellan gum/collagen hydrogel films containing different concentrations of gatifloxacin were prepared via evaporative casting method. The films were examined in terms of physical appearances, water uptake and water vapour transmission rate (WVTR). All the films showed good physical appearances. Swelling percentages of the films were decreased, whereas WVTR values were increased as the addition of gatifloxacin was increased. Swelling percentage of gellan gum/collagen film with the lowest percentage of gatifloxacin (GG/C-GAT01) has the highest swelling ratio (2057%). Meanwhile, the WVTR value of GG/C-GAT1 has the highest WVTR value among all films which is 1245 g m-2 day-1. The formulation of GG/C films with the addition of gatifloxacin with good water absorbance and acceptable WVTRs value offered promising materials to be applied as wound dressing materials.

Identification and Prevention of Microbial Contamination in Tissue Culture of Catharanthus roseus - An Important Medicinal Herb

The explants of two varities rosea and alba of Catharanthus roseus used for in vitro propagation and found to be more than 50% of the cultures became contaminated. The most common bacterial contaminants were Bacillus licheniformis, Micrococcus, Panibacillus and fungal contaminants were Fusarium, Alternaria, Cladosporium and Aspergillus. Combinations of different antibiotics (Penicillin, norfloxacin, tobramycin, gatifloxacin, ofloxacin) and fungicides (Bavastin, captan, fluconazole and trichoderma) were used to control the growth of the contaminants. Gatifloxacin and ofloxacin inhibited 100% growth of bacteria whereas, bavastin and captan appeared to be the most effective fungicides. Combination of gatifloxacin, ofloxacin with bavastin and captan inhibited the growth of contaminants at their minimum phytotoxic concentration (MIC). The observed minimum phytotoxic concentration (MPC) of ofloxacin, gatifloxacin, bavastin and captan was 15, 9, 6 and 5% at their respective MIC. More than 90% of the cultures responded for callus formation in the combination of gatifloxacin (4%) + bavastin (1%). While the combination of gatifloxacin and captan was highly toxic that reduces the growth of the culture.&#x0D; Plant Tissue Cult. &amp; Biotech. 30(2): 297-305, 2020 (December)

The impacts of Cu(II) complexation on gatifloxacin adsorption onto goethite and hematite.

Gatifloxacin (GAT) is a new generation fluoroquinolone antibiotic and its adsorption onto iron minerals influenced by coexisting trace elements [e.g., Cu(II)] has not been well investigated. To evaluate the adsorption behavior of GAT and Cu(II) onto goethite and hematite, the complexation constants of GAT with Cu(II) were determined using potentiometric titration, and the effects of Cu(II) concentration and solution pH on GAT adsorption were investigated using batch experiments. It was observed that GAT adsorption was negatively correlated with molar concentration ratio of Cu(II) to GAT. In our experimental pH range (i.e., 3.0-10.8), the calculated main species involved in GAT adsorption were Cu(GAT± )2+ and Cu(GAT± )2 2+ under acidic to neutral conditions, and formation of Cu(GAT- )2 (s) facilitated the removal of GAT from solution under alkaline condition. The adsorption data were well fitted by the Freundlich model and showed high nonlinearity. In adsorption onto goethite, the primary interactions shifted from electrostatic repulsion to formation of goethite-Cu(II)-GAT ternary surface complexes with increase of GAT concentration. For hematite, electrostatic repulsion was the main inhibiting mechanism and became stronger with increase of Cu(II) concentration. Our findings suggest that it is necessary to consider the complexation between GAT and coexisting metal cations in evaluating its transport in soils rich in different iron minerals.

Comparison of the permeability between the rabbit cornea and sclera ex vivo

Objective: Comparison of the permeability between the rabbit cornea and sclera ex vivo by determining the concentration of gatifloxacin using LC-MS/MS method, which may provide the basis for a new route of drug administration. Methods: Experimental study. The permeability of the cornea and sclera in healthy male New Zealand rabbits was evaluated by using Franz diffusion pool. We chose both gatifloxacin ophthalmic solution and gel as the test drugs, and calculated the cumulative permeation amounts (Qn), apparent permeability coefficient(P(app)). Results: The linear range of gatifloxacin was 5-1 000 ng/ml. The intra-day and inter-day precision was 1.7% -2.8% and 1.0% - 2.3%. Q(n) and P(app) of gatifloxacin ophthalmic solution in cornea and sclera ex vivo were 177.57, 517.52 μg/cm(2) and 4.34, 12.51 cm/s respectively, whereas that of gatifloxacin ophthalmic gel were 151.87, 411.05 μg/cm(2) and 3.66, 9.21 cm/s. Conclusion: This validated method could be applied to determine the gatifloxacin. The cumulative permeation amounts and apparent permeability coefficient of sclera are significantly higher than that of cornea for both ophthalmic solution and gel, suggesting that the development of a new route of drug administration based on sclera may have potential advantage. (Chin J Ophthalmol, 2019, 55: 928-932).

Liquid chromatography–tandem mass spectrometry for rapid and selective simultaneous determination of fluoroquinolones level in human aqueous humor

Endophthalmitis, an intraocular infection, may lead to irreversible loss of vision. Antimicrobial chemotherapy is prescribed prior to ocular surgical procedures to avoid endophthalmitis. Fluoroquinolones are the most commonly prescribed and used antibiotics during such procedures. However, the selection of a single entity and proper regimen is not specified in medical guidelines. The objective of this study is to develop a rapid and selective simultaneous high-performance liquid chromatography-tandem mass spectroscopic method to explore the bioavailability of 4 fluoroquinolones, including 0.5% moxifloxacin hydrochloride, 0.3% gatifloxacin, 0.3% ciprofloxacin hydrochloride, and 0.3% ofloxacin, in human aqueous humor after antibiotic topical administration using gemifloxacin as Internal Standard according to the European Medicines Agency (EMA) and US Food and Drug Administration (FDA) guidelines. The newly validated method was capable of accurately and precisely quantifying each antibiotic at the lowest reported lower limit of quantification of 10 ng/mL and operating on a very low pipetting volume of 15 μL, indicating a reliable quantitation of all analytes simultaneously using a very small quantity of aqueous humor with total chromatographic run time of 2.5 min. Sixty-seven patients were divided into 4 groups for each antibiotic. Before the cataract surgery, each group received 4 drops of one of the antibiotics over 1 h, separated by 15 min time interval. After 15–20 min from the last drop, approximately 50–100 μL of aqueous humor was collected during surgery for analysis. The average concentrations of moxifloxacin, gatifloxacin, ofloxacin and ciprofloxacin in aqueous humor samples were 891.8, 271.7, 191.4 and 69.5 ng/mL, respectively. Only moxifloxacin average concentration was higher than the minimum inhibitory concentration for the common endophthalmitis pathogens.

First derivative synchronous fluorescence spectroscopy for the determination of Gatifloxacin in presence of its oxidative degradation product: Application to pharmaceutical preparation

A highly accurate and precise spectrofluorimetric method was established for quantitation of Gatifloxacin in pure material, pharmaceutical formulations and in the existence of its oxidative degradation product. The emission was recorded at 487 nm after the excitation at 290 nm. Using micelle, sodium dodecyl sulphate (SDS), enhanced fluorescence intensity of Gatifloxacin-SDS complex. The optimization of numerous experimental conditions was carried out. The improved emission showed a suitable linear correlation between derivative synchronous fluorescence power and concentration of Gatifloxacin over the range of 10 to 100 ng/mL with a determination coefficient equals 0.9996. Studying cytotoxicity and antimicrobial susceptibility for oxidative degradation product of Gatifloxacin was carried out using Gatifloxacin as a control. In comparison, the proposed method presented a superior sensitivity and enhanced stability over the reported method.

Conjunctival Bacteria Flora of Glaucoma Patients During Long-Term Administration of Prostaglandin Analog Drops

To investigate the effects of the long-term use of prostaglandin analogs for glaucoma treatment on the indigenous flora of the conjunctiva. Bacterial isolates were collected from the conjunctival sacs of 68 patients at Miyata Eye Hospital from February to September 2014, who had been receiving continuous monotherapy with prostaglandin analogs for glaucoma for at least 1 year. Minimum inhibitory concentrations of levofloxacin, gatifloxacin, moxifloxacin, cefmenoxime, tobramycin, chloramphenicol, and erythromycin against the isolates were measured to determine susceptibility. The positive culture rate in all cases was 90.5% (57/63 eyes), and a total of 79 bacterial strains were isolated. The isolated bacteria included aerobic gram-positive cocci (8% Staphylococcus aureus and 41% Staphylococcus epidermidis), coagulase-negative staphylococci (5%), Streptococcus spp. (1%), Corynebacterium spp. (4%), gram-negative bacteria (4%), and the facultative anaerobe Propionibacterium acnes (33%). The positive culture rates for patients using 0.005% latanoprost (Xa group) and 0.004% travoprost (Tz group) were 88.9% and 92.6%, respectively, with no statistically significant difference in the composition of isolated bacteria between groups. Methicillin-resistant S. epidermidis (MRSE) was significantly more frequently isolated in the Xa group. The antimicrobial susceptibility rates of S. epidermidis were significantly lower in the Xa group for levofloxacin, gatifloxacin, moxifloxacin, and tobramycin. The indigenous flora may be affected by the long-term use of prostaglandin analogs. The higher incidence of MRSE in the Xa group should be considered during the long-term, continuous administration of eye drops, such as in glaucoma treatment.

Antimicrobial activity against Gram-positive and Gram-negative bacteria during gatifloxacin degradation by hydroxyl radicals

Gatifloxacin, an antimicrobial drug belonging to the fluoroquinolone family, is active against Gram-positive and Gram-negative bacteria and is extensively used for the control of infections in humans. The presence of the drug in environmental matrices has already been reported. This study investigated the degradation of gatifloxacin in water by hydroxyl radicals generated by the UV254nm/H2O2 process ([Formula: see text] 0.4-2.4mmol L-1) and evaluated the capacity of the radicals to reduce the antimicrobial activity against Gram-positive and Gram-negative bacteria. Acute toxicity assays were performed with Vibrio fischeri, and the degradation products were proposed. The hydroxyl radicals formed in the processes were able to degrade the fluoroquinolone and remove the antimicrobial activity from the aqueous solution. Approximately 97% gatifloxacin degradation was observed after applying 2.4mmolL-1 of initial H2O2 concentration and 20min of UVC254nm irradiation (130Js-1). The acute toxicity assays showed that the toxicity of the treated solution for V. fischeri increased as the gatifloxacin concentration in the solution decreased.

Electrochemical sensor based on electro-polymerization of β-cyclodextrin and reduced-graphene oxide on glassy carbon electrode for determination of gatifloxacin

A novel electrochemical sensor for gatifloxacin based on one-pot electro-polymerization of β-cyclodextrin (β-CD) and reduced-graphene oxide (rGO) modified glassy carbon electrode (GCE) (β-CD/rGO/GCE) was built for the first time. Scanning electron microscope (SEM) image and Infrared spectroscopy (IR) show that polymer of β-cyclodextrin and reduced graphene oxide (rGO) has been successfully modified on electrode. The electrochemical properties of this polymer were characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The optimization of the electro-polymerized cycle, the pH of supporting electrolyte and the accumulation potential and time were discussed in details. Under optimum conditions, the differential pulse voltammogram (DPV) exhibited the oxidation peak currents were linearly proportional to gatifloxacin concentrations in the range from 0.05μM to 150μM with a sensitivity of 0.33μAμM−1. This electrochemical sensor had a low detection limit of 0.02μM (S/N=3). Moreover, this proposed sensor exhibited good reproducibility, long-term stability and fast current response. To further study the practical applicability of the proposed sensor, the modified electrode was successfully applied to detect gatifloxacin in tablets and human urine samples.

Potential Antimicrobial Effects of Gatifloxacin on Periodontopathic Bacteria &amp;lt;i&amp;gt;in Vitro&amp;lt;/i&amp;gt;

The aim of this study was to identify the potential antibacterial effects of gatifloxacin on periodontal pathogens including Aggregatibacter actinomycetemcomitans, Porphyromonas gingi-valis, and Prevotella intermedia. The minimum inhibitory concentrations (MIC) of gatifloxacin and its bactericidal effects were investigated. Gatifloxacin inhibited the growth of all three kinds of periodontopathic bacteria tested in broth. The MIC value of 2.5 nM was found to be the most effective in inhibiting A. actinomycetemcomitans. An adenosine triphosphate biolumi-nescence assay revealed that gatifloxacin exhibited bactericidal effects on the tested bacteria in a time-dependent manner. The safety of gatifloxacin in mammalian cells was evaluated by assessing the viability of normal human dermal fibroblast (NHDF) cells treated with gatifloxacin. Almost all NHDF cells survived after 2-d culture, while 81% of the cells survived after 4-d culture when treated with 1.0 × 103 nM gatifloxacin. These results indicate that gatifloxacin is a possible drug for local administration to prevent periodontal infection.

Nontuberculous mycobacterial ocular infections--comparing the clinical and microbiological characteristics between Mycobacterium abscessus and Mycobacterium massiliense.

PurposeTo analyze the clinical characteristics of nontuberculous mycobacterial (NTM) ocular infections and the species-specific in vitro antimicrobial susceptibility.Material and MethodsIn 2000 to 2011 at the National Taiwan University Hospital, multilocus sequencing of rpoB, hsp65 and secA was used to identify NTM isolates from ocular infections. The clinical presentation and treatment outcomes were retrospectively compared between species. Broth microdilution method was used to determine the minimum inhibitory concentrations of amikacin (AMK), clarithromycin (CLA), ciprofloxacin (CPF), levofloxacin (LVF), moxifloxacin (MXF) and gatifloxacin (GAF) against all strains. The activities of antimicrobial combinations were assessed by the checkerboard titration method.ResultsA total of 24 NTM strains (13 Mycobacterium abscessus and 11 Mycobacterium massiliense) were isolated from 13 keratitis, 10 buckle infections, and 1 canaliculitis cases. Clinically, manifestations and outcomes caused by these two species were similar and surgical intervention was necessary for medically unresponsive NTM infection. Microbiologically, 100% of M. abscessus and 90.9% of M. massiliense ocular isolates were susceptible to amikacin but all were resistant to fluoroquinolones. Inducible clarithromycin resistance existed in 69.3% of M. abscessus but not in M. massiliense isolates. None of the AMK-CLA, AMK-MXF, AMK-GAF, CLA-MXF and CLA-GAF combinations showed synergistic or antagonistic effect against both species in vitro.Conclusions M. abscessus and M. massiliense are the most commonly identified species for NTM ocular infections in Taiwan. Both species were resistant to fluoroquinolones, susceptible to amikacin, and differ in clarithromycin resistance. Combined antimicrobial treatments showed no interaction in vitro but could be considered in combination with surgical interventions for eradication of this devastating ocular infection.

Antifungal effect of Gatifloxacin and copper ions combination.

It is a well-known fact that to bring a new molecule it may take more than a decade. The existing drugs, which are known for their adverse reaction or toxicity, if utilized and allowed in different formulation, the new effective formulation may be discovered and developed. This may help in reducing various side effects, time and costs. In this study, fungal infection was inoculated superficially over the skin of guinea pigs and treated with the broad-spectrum antimicrobial (gatifloxacin) in combination with non-toxic and effective amount of copper ions. MIC of copper (0.20%) was also determined. Concentration of gatifloxacin (100 μg ml(-1)) with the combination of copper ions (MIC) at which it inhibits the visible growth of fungal strains was also evaluated. Hematological parameters, such as total leukocyte count and differential leukocyte count, were evaluated. The results have shown increase in these parameters after fungal infection, which reaches its normal value after treatment with the combination of gatifloxacin and copper ions. Outcomes of the research concluded that gatifloxacin 100 μg ml(-1) can be used by 0.20% of copper ions to prevent growth of some fungal strains (Candida albicans and Aspergillus niger), which causes skin infections with more potency.

Delivery of gatifloxacin using microemulsion as vehicle: formulation, evaluation, transcorneal permeation and aqueous humor drug determination

The successful ophthalmic delivery system is reliant on the diminution in the precorneal loss of drugs by increasing the corneal contact time and increasing the transcorneal permeability, which may enhance the bioavailability of drug to the eyes. The objective of this investigation was to develop and evaluate the potential of microemulsions of gatifloxacin with respect to the conventional eye drops of gatifloxacin. Oil-in-water microemulsions were prepared with different concentrations of oil, surfactant and co-surfactant using aqueous titration method. All formulations showed circular shape droplets, displayed an average droplet size ranged between 51 and 74 nm and absolute zeta potential values ranged from 15 to 24 mV, with optimum physicochemical characteristics suitable for eye. The optimized microemulsion possessed good stability, showed greater adherence to corneal surface and good permeation of gatifloxacin in the anterior chamber of the eye, resulting in a twofold increase in gatifloxacin concentration than the conventional dosage form. Hence, the optimized microemulsions showed increased intraocular penetration and enhance ocular bioavailability of gatifloxacin.

Association of gyrA/B mutations and resistance levels to fluoroquinolones in clinical isolates of Mycobacterium tuberculosis

To evaluate the association between mutations in the genes gyrA/B and resistance levels to fluoroquinolones in clinical isolates of Mycobacterium tuberculosis, a total of 80 ofloxacin-resistant isolates collected in 2009 by the Shanghai Municipal Centers for Disease Control and Prevention were studied. The minimum inhibitory concentration (MIC) of ofloxacin, moxifloxacin and gatifloxacin for each isolate was determined using the microscopic observation drug susceptibility assay. Sequencing was used to identify mutations in the quinolone resistance-determining region (QRDR) of the gyrA and gyrB genes. In total, 68 isolates had mutations in gyrA, three isolates had mutations in gyrB, six isolates had mutations in both gyrA and gyrB, and three isolates had no mutations. Two common mutations in gyrA, the D94G and D94N mutations, were associated with higher-level resistance to all three fluoroquinolones than two other common mutations (A90V and D94A). Understanding the relationship between MICs and mutations in ofloxacin-resistant isolates will facilitate the optimization of the use of new-generation fluoroquinolones to treat patients with ofloxacin-resistant tuberculosis (TB).

Determination of critical concentrations of moxifloxacin and gatifloxacin for drug susceptibility testing of Mycobacterium tuberculosis in the BACTEC MGIT 960 system

To determine critical concentrations of moxifloxacin and gatifloxacin for rapid evaluation of drug susceptibility of Mycobacterium tuberculosis in Middlebrook 7H9 broth using the automated system BACTEC™ MGIT™ 960. In total we studied 152 strains. Critical concentrations of moxifloxacin and gatifloxacin in the BACTEC™ MGIT™ 960 and on Lowenstein-Jensen medium were determined using a panel of 68 strains. The proportion method on Middlebrook 7H10 medium was used as a reference method. Drug susceptibility testing against fluoroquinolones was done for the other 84 strains using the established critical concentrations. The gyrA and gyrB genes of all strains were studied by molecular tests. The critical concentrations determined for moxifloxacin and gatifloxacin were 0.25 mg/L in the BACTEC™ MGIT™ 960 system and 0.75 mg/L on Lowenstein-Jensen medium (absolute concentration method). The moxifloxacin and gatifloxacin critical concentrations that we have established are reliable for rapid drug susceptibility testing in the BACTEC™ MGIT™ 960.

A selective fluorescence probe for gatifloxacin based on the fluorescence quenching of bovine serum albumin capped ZnS nanoparticles

A novel fluorescence probe based on the quenching of fluorescence of bovine serum albumin (BSA) capped ZnS nanoparticles (NPs) has been developed for the determination of gatifloxacin in bulk and pharmaceutical dosage form. The functionalized ZnS NPs were successfully synthesized in aqueous medium, with the biomolecule BSA as the capping ligand. Due to a specific interaction, the fluorescence intensity of ZnS NPs reduces obviously in the presence of gatifloxacin. Under the optimal conditions, the relative fluorescence intensity of ZnS NPs is linearly proportional to gatifloxacin concentration from 2.0×10−7M to 1.0×10−4M with a detection limit of 6.5×10−8M. The proposed method is simple, rapid, practical and can be successfully applied to assay gatifloxacin capsules.

A novel sensor based on electropolymerization of β-cyclodextrin and l-arginine on carbon paste electrode for determination of fluoroquinolones

An electrochemical sensor for fluoroquinolones (FQs) based on polymerization of β-cyclodextrin (β-CD) and l-arginine (l-arg) modified carbon paste electrode (CPE) (P-β-CD-l-arg/CPE) was built for the first time. Synergistic effect of l-arg and β-CD was used to construct this sensor for quantification of these important antibiotics. Scanning electron microscope (SEM) image shows that polymer of β-CD and l-arg has been successfully modified on electrode. Electrochemical impedance spectroscopy (EIS) and cyclic voltammograms (CV) further indicate that polymer of β-CD and l-arg efficiently decreased the charge transfer resistance value of electrode and improved the electron transfer kinetic between analyte and electrode. Under the optimized conditions, this modified electrode was utilized to determine the concentrations of ciprofloxacin, ofloxacin, norfloxacin and gatifloxacin. The differential pulse voltammogram (DPV) exhibits the oxidation peak currents were linearly proportional to their concentration in the range of 0.05–100μM for ciprofloxacin, 0.1–100μM for ofloxacin, 0.1–40μM for norfloxacin and 0.06–100μM for gatifloxacin, respectively. This method was also successfully used to detect the concentrations of each drug in pharmaceutical formulations and human serum samples. In addition, this proposed fluoroquinolones sensor exhibited good reproducibility, long-term stability and fast current response.

Determination of Gatifloxacin in Milk and Biological Fluids by Inhibitory Resonance Fluorescence Spectrometry

A novel method for the determination of trace gatifloxacin was established by resonance fluorescence techniques. It was based on the fact that oxidation of rhodamin 6G by hydrogen peroxide and Cu2+ was inhibited by gatifloxacin in Tris-HCl buffer medium and in presence of cetyl trimethyl ammonium bromide. The enhanced intensity (ΔF) of resonance fluorescence at 540 nm was proportional to the concentration of gatifloxacin in the range of 9.8 × 10−3 − 1.75 µg mL−1. The limit of detection was 2.9 ng mL−1 and the average recovery was 101.8% (n = 6) for gatifloxacin. The present method was applied to the determination of trace gatifloxacin in milk and biological fluids, and the obtained results were in good agreement with those obtained by HPLC.