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Serum concentrations of cefepime (BMY-28142) were determined for four dosing regimes, 10 mg/kg or 20 mg/kg, given as single subcutaneous (SC) or intramuscular injections (IM) to dogs. Serial serum samples were analyzed for the presence of cefepime by high-performance liquid chromatography. In experiment 1, the overall mean (+/- SEM) serum concentration (for a 12-hour period) after a dose of 20 mg/kg for SC and IM routes (4.9 +/- 0.74 micrograms/ml and 5.5 +/- 0.63 micrograms/ml, respectively) was twice that for the 10 mg/kg dose given either SC or IM (2.2 +/- 0.31 micrograms/ml and 2.8 +/- 0.47 micrograms/ml, respectively). There was no significant difference (p greater than 0.05) in mean serum concentrations for SC and IM routes of administration at the same dosage. In subsequent experiments, 5 doses of cefepime (20 mg/kg) were administered IM at 12-hour (experiment 2) or 24-hour (experiment 3) intervals. The mean (+/- SEM) peak serum concentration was 12.1 +/- 1.59 micrograms/ml, 2 hours after the 2nd injection in experiment 2. In experiment 3, the mean (+/- SEM) peak serum concentration was 10.9 +/- 1.34 micrograms/ml, 4 hours after the 1st injection. Mean trough concentrations in experiment 2 were greater than or equal to 0.5 microgram/ml and less than or equal to 0.5 in experiment 3. Multiple IM doses produced transient edema at the injection site and mild lameness in all dogs. Cefepime was highly active against single canine isolates of Staphylococcus intermedius, Pseudomonas aeruginosa and Escherichia coli, with minimum inhibitory concentrations of 0.125 microgram/ml, 1 microgram/ml and 0.3 microgram/ml, respectively.

Eight calves with suppurative arthritis were each given a single intramuscular injection of ampicillin trihydrate at a dose of 10 mg/kg. Ampicillin concentrations were measured serially in serum and in suppurative and normal synovial fluid over a 24-hour period. The mean peak serum concentration was 2.5 +/- 0.54 micrograms/ml 2 hours after injection. The highest concentration in normal synovial fluid was 3.5 +/- 0.40 micrograms/ml at 4 hours and the highest concentration in suppurative synovial fluid was 2.7 +/- 0.58 micrograms/ml at 2 hours. Overall mean ampicillin concentration in normal synovial fluid for the first 8 h (2.9 +/- 0.32 micrograms/ml) was significantly different from that in suppurative synovial fluid (2.1 +/- 0.33 micrograms/ml) and serum (1.9 +/- 0.30 micrograms/ml; p less than 0.05).