title: Pharmacokinetics of penicillin-G in serum and nasal washings of Pasteurella multocida free and infected rabbits.
abstract: Treatment of infections due to Pasteurella multocida in rabbits usually consists of a single intramuscular injection of penicillin G and results in variable cure rates. We report here the levels of penicillin G in serum and nasal washings in P. multocida free and P. multocida infected rabbits following a single intramuscular injection over a 24 hours period. These levels were compared to the minimal inhibitory concentrations (MICS) of 50 clinical isolates of P. multocida of rabbit origin. Infected rabbits demonstrated higher serum levels of penicillin G over P. multocida free rabbits at 1, 3, and 5 hours after the injection. At 16 and 24 hours the penicillin G serum levels dropped to 0.14 and 0.07 microgram/ml, respectively, from 1.90 micrograms/ml at 8 hours. At these levels of penicillin G only 20% of the isolates tested in vitro for susceptibilities (MICs) would be inhibited. Levels of penicillin G in nasal washings at 4 hours after injection were 0.063 microgram/ml, or one-fourth the MIC of 80% of the P. multocida isolates tested (0.25 microgram/ml). In contrast, serum levels of approximately 5 micrograms/ml were seen at this time. Our results suggest that therapeutic blood levels could be achieved if rabbits are given injections of procaine penicillin G at 8 hour intervals.
mesh_terms: D000818:Animals; D005260:Female; D007273:Injections, Intramuscular; D007700:Kinetics; D009297:Nasal Mucosa / Q000378:metabolism*; D010326:Pasteurella Infections / Q000188:drug therapy / Q000662:veterinary*; D010400:Penicillin G / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism / Q000627:therapeutic use*; D011817:Rabbits; D007507:Therapeutic Irrigation
chemical_list: D010400:Penicillin G