n-desmethyldanofloxacin and danofloxacin

The objectives of this study were to investigate the pharmacokinetics of danofloxacin and its metabolite N-desmethyldanofloxacin and to determine their concentrations in synovial fluid after administration by the intravenous, intramuscular or intragastric routes. Six adult mares received danofloxacin mesylate administered intravenously (i.v.) or intramuscularly (i.m.) at a dose of 5 mg/kg, or intragastrically (IG) at a dose of 7.5 mg/kg using a randomized Latin square design. Concentrations of danofloxacin and N-desmethyldanofloxacin were measured by UPLC-MS/MS. After i.v. administration, danofloxacin had an apparent volume of distribution (mean ± SD) of 3.57 ± 0.26 L/kg, a systemic clearance of 357.6 ± 61.0 mL/h/kg, and an elimination half-life of 8.00 ± 0.48 h. Maximum plasma concentration (Cmax ) of N-desmethyldanofloxacin (0.151 ± 0.038 μg/mL) was achieved within 5 min of i.v. administration. Peak danofloxacin concentrations were significantly higher after i.m. (1.37 ± 0.13 μg/mL) than after IG administration (0.99 ± 0.1 μg/mL). Bioavailability was significantly higher after i.m. (100.0 ± 12.5%) than after IG (35.8 ± 8.5%) administration. Concentrations of danofloxacin in synovial fluid samples collected 1.5 h after administration were significantly higher after i.v. (1.02 ± 0.50 μg/mL) and i.m. (0.70 ± 0.35 μg/mL) than after IG (0.20 ± 0.12 μg/mL) administration. Monte Carlo simulations indicated that danofloxacin would be predicted to be effective against bacteria with a minimum inhibitory concentration (MIC) ≤0.25 μg/mL for i.v. and i.m. administration and 0.12 μg/mL for oral administration to maintain an area under the curve:MIC ratio ≥50.

Topics: Animals; Area Under Curve; Biological Availability; Female; Fluoroquinolones; Half-Life; Horses; Injections, Intramuscular; Injections, Intravenous; Quinolones; Synovial Fluid

A rugged, simple, and selective method for the determination of danofloxacin and its primary metabolite, N-desmethyldanofloxacin, in cattle (liver, muscle, kidney, and fat) and chicken (liver and muscle) tissues was developed. The method is selective for danofloxacin and N-desmethyldanofloxacin over other veterinary important fluoroquinolones, such as enrofloxacin, ciprofloxacin, norfloxacin, and ofloxacin. Selectivity is achieved through a combination of extraction, chromatography, and fluorescence detection. The analytes were extracted from homogenized tissues using a methanol-perchloric-phosphoric acid solution. After centrifugation, direct injection of extraction supernate was possible. The limit of quantitation was 20 pg on column. Separation was achieved on an Inertsil C8 (5 microns, 100 A) column with dimensions of 250 x 4.6 mm I.D. The mobile phase consisted of 0.05 M phosphate buffer (pH 3.5)-acetonitrile (88:12). A fluorescence detector was utilized with an excitation wavelength of 280 nm and an emission wavelength of 440 nm. The assay was accurate and reproducible within the range of 10 to 500 ng/g for both danofloxacin and N-desmethyldanofloxacin. Intra-assay accuracy was between 98 and 101%, and precision was less than 4%. Inter-assay accuracy was between 99 and 102%, while precision was less than 2%. Recoveries for both analytes over the dynamic range were greater than 90% for all the tissues.

Topics: Adipose Tissue; Animals; Anti-Infective Agents; Cattle; Chickens; Fluoroquinolones; Kidney; Liver; Meat; Muscles; Quinolones; Reproducibility of Results; Spectrometry, Fluorescence

A series of novel 6-fluoro-7-diazabicycloalkylquinolonecarboxylic acids substituted with various C8 (H, F, Cl, N) and N1 (ethyl, cyclopropyl, vinyl, 2-fluoroethyl, 4-fluorophenyl, 2,4-difluorophenyl) substituents, as well as, 9-fluoro-10-diazabicycloalkylpyridobenzoxazinecarboxylic acids, were prepared and evaluated for antibacterial activity against a range of important veterinary pathogenic bacteria. The diazabicycloalkyl side chains investigated at the 7-position (benzoxazine 10-position) include (1S,4S)-5-methyl-2,5-diazabicyclo[2.2.1]heptane (2), (1S,4S)-2,5-diazabicyclo[2.2.1]heptane (3), (1R,4R)-5-methyl-2,5-diazabicyclo[2.2.1]heptane (4), 8-methyl-3,8-diazabicyclo[3.2.1]octane (5), 9-methyl-3,9-diazabicyclo[4.2.1]nonane (6), 1,4-diazabicyclo[3.2.2]nonane (7), 1,4-diazabicyclo[3.3.1]nonane (8), and 9-methyl-3,9-diazabicyclo[3.3.1]nonane (9). Among these side chains, in vitro potency was not highly variable; other properties therefore proved more critical to the selection of possible development candidates. However, the relative potencies observed for several of these compounds in mouse, swine, and cattle infection models correlated well with those seen in vitro. A combination of the N1 cyclopropyl group and the C7 (1S,4S)-5-methyl-2,5-diazabicyclo[2.2.1]hept-2-yl appendage conferred the best overall antibacterial, physiochemical, and pharmacodynamic properties. Hence, danofloxacin (Advocin, 2c) (originally CP-76,136, 1-cyclopropyl-6-fluoro-7-[(1S,4S)-5-methyl-2,5-diazabicyclo[2.2.1] hept-2-yl]-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid) was selected as a candidate for development as a therapeutic antibacterial agent for veterinary medicine.

Topics: Actinobacillus Infections; Actinobacillus pleuropneumoniae; Aerobiosis; Anaerobiosis; Animals; Anti-Infective Agents; Bacterial Infections; Cattle; Cattle Diseases; Female; Fluoroquinolones; Gram-Negative Bacteria; Gram-Positive Bacteria; Mice; Molecular Structure; Pasteurella Infections; Quinolones; Structure-Activity Relationship; Swine; Swine Diseases