Determination of lomefloxacin in human plasma by solid-phase extraction and high-performance liquid chromatography with UV detection

A novel spectrofluorimetric method for determination of lomefloxacin adopting on zinc(II) chelation strategy: Application in human plasma

A new sensitive and instantaneous spectrofluorimetric method for efficient determination of lomefloxacin (LMX) in its pure, dosage form and human plasma was designed. The developed method depends on formation of a metal-chelation compound of LMX as a ligand with zinc(II) in a buffer of acetate (pH 5.5). The following parameters; type of metal, concentration of metal, pH, type of buffer and diluting solvent were optimized. After carefully investigation; 0.2 mM zinc, 2.0 ml acetate buffer (pH 5.5) and water as diluting solvent were set as optimum reaction conditions. Under these conditions, a large increase in the intensity of the fluorescence of LMX was attained at 450 after excitation at 284 nm. The limits of detection and quantification were 5.8 and 1.9 ng ml^-1 , respectively, with linearity range of 10.0 to 500.0 ng ml^-1 . The binding mode of LMX and zinc(II) ion (Zn²⁺ ) was found to be 2:1, respectively, and confirmed by Job's plot method. Furthermore, it extended to the analysis of LMX in the spiked plasma of humans with percentage recovery (98.70 ± 0.97 to 100.30 ± 1.69%, n = 3).

The simultaneous separation and determination of five quinolone antibotics using isocratic reversed-phase HPLC: Application to stability studies on an ofloxacin tablet formulation

A rapid and reliable HPLC method was developed for the simultaneously separation and quantitation of five quinolones antibiotics; nalidixic acid, norfloxacin, ofloxacin, ciprofloxacin and lomefloxacin. All five tablet formulations of individual quinolone antibiotics were routinely assayed without interference. The calibration curves were linear (r2> or =0.999) over the concentration range of 1.20-4.8 mg/100 ml. Selectivity, precision, sensitivity and accuracy were established and the method is stability indicating with respect to ofloxacin. The limit of detection and quantitation for ofloxacin was 18 and 36 microg/100 ml, respectively. The separation was performed on a Phenomenex ODS C18 column using an isocratic, ion-pairing mobile phase consisting of 35% (v/v) aqueous acetonitrile together with tetrabutylammonium acetate, sodium dodecyl sulphate and citric acid (pH* 3.4). All analyses were conducted at ambient temperature and was monitored using a Diode Array UV/VIS detector set at wavelengths 235, 254, 275 and 300 nm.

Development and validation of high-performance liquid chromatographic method for determination of ofloxacin and lomefloxacin in human plasma

Ahigh-performance liquid chromatographicmethod for the determination of ofloxacin and lomefloxacin in human plasma has been developed and validated. The effect of organic modifiers on the retention of the investigated drugs was investigated. A simple isocratic chromatographic assay with UV-detection at 280nm was performed on a Hibar Lichrospher 100 RP 8 column (250x4.6mm 5?m. Merck, Germany) using a mixture of acetonitrile and 0.5 % triethylamine in water (pH adjusted to 2.5 with H3PO4) (15:85, V/V) as the mobile phase at flow rate of 1.2 mL min-1. The calibration curves were linear in the concentration ragne of 0.5-6.0?g mL-1 for ofloxacin and 0.2-4.5 ?g mL-1 for lomefloxacin.

Electrochemical Adsorptive Behavior of Some Fluoroquinolones at Carbon Paste Electrode

Cyclic voltammetry and differential pulse voltammetry were used to explore the adsorption behavior of three antibacterial agents at a carbon paste electrode. The drugs were accumulated on a carbon paste electrode, and a well-defined oxidation peak was obtained in acetate buffer (pH 5.0). The adsorptive stripping response was evaluated as a function of some variables such as the scan rate, pH and accumulation time. A simple, precise, inexpensive and sensitive voltammetric method has been developed for the determination of the cited drugs (Lomefloxacin (LFX), Sparfloxacin hydrochloride (SFX), and Gatifloxacin (GFX)). A linear calibration was obtained from 2 x 10(-7) M to 4 x 10(-5) M for LFX, 2 x 10(-7) M to 6 x 10(-5) M for SFX, and GFX. The limits of detection (LOD) were 4.2 x 10(-7), 7 x 10(-7) and 6.6 x 10(-7) M, while the limits of quantification (LOQ) were 1.4 x 10(-6), 2.3 x 10(-6) and 2.2 x 10(-6) M for LFX, SFX, and GFX, respectively. The R. S. D. of five measurements at the 1 x 10(-6) M level were 0.4, 0.5 and 0.3 for LFX, SFX and GFX, respectively. The method was applied to the determination of LFX, SFX and GFX in dilute urine samples and dosage forms, and compared with the HPLC method.

Fluorescence spectroscopy determination of fluoroquinolones by charge-transfer reaction

The charge-transfer (CT) reaction between chloranilic acid (CL) as a pi-electron acceptor and lomefloxacin (LOM), fleroxacin (FLX), ciprofloxacin (CPFX), norfloxacin (NOR) as electron donor have been studied by fluorimetry. The CT complexes have stable purple color in acetone solution and the fluorescence intensity of the CT complexes was enhanced in 4-14 fold higher than that of the four fluoroquinolones (FQS) itself, therefore a new spectrofluorimetric method with simple, rapid, accurate, high sensitivity and good selectivity for determination of the four FQS has been developed. The method was applied for determination of drugs (LOM, FLX, CPFX and NOR) in tablets with mean percentage accuracies 99.80+/-1.12, 99.93+/-0.92, 99.23+/-1.36 and 99.87+/-0.81, respectively.

Differential-pulse adsorptive stripping voltammetric determination of the antibacterial lomefloxacin

A differential-pulse adsorptive stripping voltammetric method for the determination of trace amounts of the antibacterial lomefloxacin is proposed. By using an accumulation potential of -0.30 V and a 2 min accumulation time, the linear concentration range of application was 1.0-10.0 ng ml(-1) of lomefloxacin, with a relative standard deviation of 3.8% (for a level of 5.0 ng ml(-1)) and a detection limit of 0.3 ng ml(-1). The method was applied to determination of lomefloxacin in human urine and serum samples. It was validated using HPLC as a reference method. Recovery levels of the method reached 100% in all cases.

Analysis of fluoroquinolones in biological fluids by high-performance liquid chromatography

High-performance liquid chromatographic methods for the analysis of fluoroquinolones in biological fluids are reviewed. In particular, sample preparation and handling procedures, chromatographic conditions, and detection methods are discussed. A summary of published high-performance liquid chromatographic assays for individual fluoroquinolones is included.

Stereospecific high-performance liquid chromatographic assay of lomefloxacin in human plasma

This report describes an HPLC assay developed for the quantification of the enantiomers of lomefloxacin (LFLX), a quinolone antibiotic, in plasma. Following addition of racemic acebutolol (internal standard, IS), plasma samples were extracted at pH 7 with a mixture of chloroform-isopentyl alcohol-diethyl ether (71.25:3.75:25, v/v/v). The organic layer was evaporated, and LFLX and IS enantiomers in the resulting residue were derivatized with chloroform solutions of 1% triethylamine and 1% (S)-(+)-(1-naphthyl)ethyl isocyanate, followed by 2% ethyl chloroformate (ECF) 1 min later. Ethanolamine was added 30 s after the addition of ECF. The enantiomers were separated as diastereomers on an 8 x 100 mm Radial Pak normal phase column using a mobile phase of hexane-chloroform-methanol (64.5:33:2.5, v/v/v) pumped at 2.0 ml min-1. The IS was detected by fluorescence at 245 and 420 nm (excitation and emission, respectively) during the first 12 min, after which time the wavelengths were 280 and 470 nm for detection of LFLX. The method: (1) was sensitive and showed excellent linearity (10-1000 ng ml-1, r2 > 0.99) between added enantiomer concentrations and peak-area-ratio (LFLX/IS); and (2) separated LFLX and IS enantiomers within 25 min. The assay is suitable for the quantification of LFLX enantiomers in plasma samples.