Antibiotics in exudate from periapical lesions in dogs.

Forty-eight periapical lesions were induced in the mandible of dogs. Subsequently, the dogs were given a single intramuscular injection of either benzylpenicillin, erythromycin, lincomycin or clindamycin. The antibiotic concentration in serum and exudate from the periapical lesions was measured. The highest concentration of benzylpenicillin in serum (4.3 micrograms/ml) was obtained 30 min after the injection and in exudate (1.8 micrograms/ml) 60 min after injection. The highest concentration of erythromycin in serum (0.8 microgram/ml) was reached after 120 min and in exudate (0.6 microgram/ml) 240 min after the injection. The highest concentration of clindamycin in serum (2.3 micrograms/ml) was obtained 120 min after the injection and in the exudate (2.2 micrograms/ml) after 240 min. The highest concentration of lincomycin in serum (4.2 micrograms/ml) was noted 120 min after the injection and in exudate (4.5 micrograms/ml) 240 min after the injection. The results of this study indicated that the sampling method used might be suitable for analyzing the concentration of antibiotics in a clinical situation.