Abstract

Enrofloxacin (EFX) belongs to fluoroquinolone family, targeting gram-negative and some gram-positive bacteria as well as Mycoplasma spp. Flunixin (FL) is a nonsteroidal anti-inflammatory drug (NSAID) inhibiting cycloxygenase enzymes in the arachidonic acid cascade, blocking the formation of inflammatory mediators. NSAIDs are frequently coadministered to enhance the rate of recovery in combination with antimicrobial drugs in calves suffering from endotoximia, pneumonia and other viral and bacterial respiratory diseases. However, it has been reported that the distribution and elimination of antimicrobials are altered when they are coadministered with NSAIDs.This work was performed to characterize EFX disposition and establish the influence of the coadministration of FL on kinetic parameters. Lactating calves (N= 6) received 5 mg of intramuscular EFX, a week later 5 mg / kg of EFX and 2.2 mg of flunixin meglumine intramuscularly. At different times for 24 hours blood samples were obtained, centrifuged and stored at -20 °C. The preparative test consisted of extraction of the analyte with 200 μL of plasma, 200 μL of water, 750 μL of methanol: water: acid: phosphoric acid (500: 500: 10: 1 v / v / v / v) and 50 μL of 25% trichloroacetic acid. The whole was stirred 30” in vortex and centrifuged 30 minutes at 13500 rpm at 4 °C. Separation and quantification were performed by reverse phase isocratic elution with C-18 column and reading in fluorescence detector at lex 295 nm y lem 490, mobile phase composed of water, acetonitrile and triethylamine (79: 20: 1 v / v / v) at pH 3. Plasma concentration data were analyzed by PK Solution 2.0 software to calculate robust kinetic parameters. Results indicates rapid absorption and distribution of EFX and moderate permanence in the organism. Statistical non-parametric Mann-Whitney test was used. It can be verified that the coadminstration of FL did not significantly modify (P <0.05), the kinetic parameters of marbofloxacin