T HE study was done to compare the pharmacokinetic and pharmacodynamics of 50 mg/ kg b.wttetracycline hydrochloride (TC-hcl) and tetracycline nanoemulsion (TC-nm) formulasin rabbits and detection of their effect on stander and field bacterial strains. After oral TC concentration in plasma started to be detected at 0.25 h, reach the maximum at (0.5 h Tc-hcl) and 1 h.(TC-nm) and decline at 12 hours. Following a single i.v administration a volume of distribution V2 (0.292±0.111 L/kg) in TC-nm than for TC-hcl (0.216 ± 0.183L/kg) and was slowly cleared (0.393±0.183 L.h/kg) in Tc-nm than in TC-hcl (0.415±0.311 L.h/kg). After oral administration a rapidly absorbed with significant slowly absorption half-life t1/2 alpha (0.550±0.090 h and 0.176±0.058 h.) and elimination half-life t1/2 beta (4.215±1.661 h. and 1.58±1.447 h.) with higher calculated Cmax of (4.215±1.661 μg/ml and 1.58±1.447 μg/ml) achieved at prolonged calculated tmax (0.759±0.149h. and 0.356±0.305 h.) in TC-nm than in TC-hcl, respectively. The value of TC-hcl and TC-nm MIC was the same for Staph. Aureus 6538, Staph. Epidermidis12228 ,E.coli 8739 were 0.14, 0.8 and 0.12 µg , respectively, and interpreted as sensitive. Field sensitive Corynebacterium, E.coli , S. typhimurium, S. enteriditisand Staph.leutus isolates MIC value was 1.4, 8, 2, 1.6 and 2 µg for , respectively. Tetracycline resistant2Staph.scuiri (18 and 16µg) and 2 Staph. xylosis (18 and 6µg).

Cefquinome is one of the fourth generations of cephalosporins developed for veterinary use in treatment of respiratory diseases that are considered the second causes of death in calves. Nonsteroidal anti-inflammatory drugs such as flunixin (NSAIDs) are widely prescribed with antibacterial agents in multiple drug prescriptions. The present study aimed to investigate the effect of co-administration of flunixin on the disposition kinetics of cefquinome after intramuscular injection in 10 diseased calves (Pasturella heamolytica infected). Cefquinome was injected in a single dose (2 mg/kg BW) in 5 diseased calves alone and coupled with flunixin (1mg/kg BW) in the other 5 diseased calves. Blood samples (5 mL) were collected from the right jugular vein of each calve immediately before treatment and at intervals of 0, 5, 10, 15 and 30 min, 1, 2, 4, 6, 8, 12, and 24 hours, 48, 72, 96 and 120 h (5 days) after cefquinome administration. The obtained samples were assayed with the plate microbiological assay method using Sarcina lutea (ATCC 9341) as test organism. The plasma cefquinome concentration at 5 min after intramuscular injection of cefquinome alone and coupled with flunixin was 0.27 ± 0.05 μg/mL and 0.35 ± 0.12 μg/mL, respectively and reached the highest concentration (1.02 ± 0.12 μg/mL and 1.02 ± 0.08 μg/mL) at 1 h, respectively. The obtained data showed no significant effect of coupled administration of flunixin with cefquinome on either concentration or peak concentration of cefquinome in plasma of diseased calves. It is concluded that flunixin can be used successfully with cefquinome in treatment of bacterial respiratory diseases associated with inflammation in calves.