Florfenicol concentrations in ovine tear fluid following intramuscular and subcutaneous administration and comparison with the minimum inhibitory concentrations against mycoplasmal strains potentially involved in infectious keratoconjunctivitis.
OBJECTIVE
To measure florfenicol concentrations in ovine tear fluid after IM and SC administration and determine minimum inhibitory concentrations (MICs) of florfenicol against field isolates of Mycoplasma organisms potentially involved in infectious keratoconjunctivitis.


METHODS
9 healthy adult Lacaune ewes.


METHODS
Animals received an IM and SC administration of florfenicol (20 mg/kg) in a 2-way crossover design. Samples of blood and tear fluid were collected before and for 24 hours after administration. Concentrations of florfenicol in plasma and tear fluid were measured via high-performance liquid chromatography. The MIC of florfenicol for various Mycoplasma strains cultured from sheep and goats was determined via an agar dilution method.


RESULTS
Mean florfenicol concentration in tear fluid for the 24-hour period was significantly higher after IM administration (0.70 μg/mL) than after SC administration (0.22 μg/mL) and was maintained for a longer duration. The lacrimal fluid-to-plasma concentration ratio was not different between the 2 routes of administration, with mean values of 40.2% and 32.5% after IM and SC administration, respectively. The MIC for Mycoplasma agalactiae, Mycoplasma conjunctivae, and Mycoplasma mycoides isolates ranged from 0.5 to 8 μg of florfenicol/mL. Two strains of M agalactiae could be considered resistant to florfenicol.


CONCLUSIONS
Florfenicol readily penetrated the preocular tear fluid of sheep after IM and SC administration. For both routes of administration, doses > 20 mg/kg would be necessary to achieve tear fluid concentrations of florfenicol greater than the MICs for most strains of Mycoplasma organisms.
UMR 181 Physiopathologie et Toxicologie Expérimentales, INRA, Ecole Nationale Vétérinaire, 23 chemin des Capelles, B.P. 87614, 31076 Toulouse Cedex 03, France. a.regnier@envt.fr
Alain
A
Regnier
Valérie
V
Laroute
Anne
A
Gautier-Bouchardon
Véronique
V
Gayrard
Nicole
N
Picard-Hagen
Pierre-Louis
PL
Toutain
D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000032:analysis / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D018592:Cross-Over Studies; D005260:Female; D007273:Injections, Intramuscular / Q000662:veterinary; D007279:Injections, Subcutaneous / Q000662:veterinary; D007639:Keratoconjunctivitis, Infectious / Q000188:drug therapy*; D008826:Microbial Sensitivity Tests; D009174:Mycoplasma / Q000187:drug effects*; D009175:Mycoplasma Infections / Q000188:drug therapy* / Q000382:microbiology; D012756:Sheep; D012757:Sheep Diseases / Q000188:drug therapy*; D013045:Species Specificity; D013666:Tears / Q000737:chemistry*; D013839:Thiamphenicol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000032:analysis / Q000494:pharmacology
D000900:Anti-Bacterial Agents; C035534:florfenicol; D013839:Thiamphenicol