International clinical experience with azlocillin

Azlocillin, cephalothin, and tobramycin therapy in febrile solid tumor patients with chemotherapy-induced leukopenia

Although the semisynthetic broad-spectrum acylureido-penicillin, azlocillin has been demonstrated to have significant antibiotic activity in leukemic patients, its role in combination therapy of febrile granulocytopenic patients with chemotherapy-treated solid tumors has not been clearly delineated. Thirty-five solid tumor patients with chemotherapy-induced absolute granulocytopenia (less than 1000 granulocytes/ml) associated with fever (greater than 38.3 degrees C) were treated on a prospective study with a combination of azlocillin 4 g intravenously (IV) every 6 hours, cephalothin 2 g IV every 6 hours, and tobramycin 80 to 100 mg IV every 8 to 12 hours. Prior chemotherapy included doxorubicin combinations in 18 patients and other combinations in 17 patients. Granulocyte counts preantibiotic therapy were greater than 100 granulocyte/ml in 14 patients, 100 to 499 in nine patients, and 500 to 1000 in 12 patients. Granulocyte nadirs were less than 100 in 20 patients, 100 to 499 in nine patients, and 500 to 1000 in six patients. Times for granulocytes to rise towards normal were 1 to 3 days in eight patients, 4 to 6 days in 18 patients, and 7 or more days in nine patients. Tobramycin levels were primarily in the peak range of 3 to 6 micrograms/ml and trough range of 0 to 1.9 micrograms/ml. The site and pathogen were identified in nine patients, the infection site clinically documented without isolated pathogen in three patients, and no site or pathogen identified in 23 patients. Of the 35 patients, 34 had good responses to the antibiotic combination (complete disappearance of fever and other evidence of infection). Serum creatinine rose 0.4 to 0.6 mg/dl in nine patients, 0.7 to 1.5 in four patients, and 1.5 in one patient (obstructive uropathy). The only other noted antibiotic-related side effect was hypokalemia. This antibiotic combination had little toxicity with marked efficacy.

Azlocillin and cefonicid penetration into bone enhanced by probenecid

Azlocillin (AZL) and cefonicid (CFD) penetration into rabbit humerus and scapula was evaluated with and without concomitantly administered probenecid. Groups of animals received either 70 mg of AZL intravenously or 20 mg of CFD intramuscularly per kg of body weight; other groups were pretreated with 40 mg of probenecid per kg before the administration of antibiotics. Peak levels of AZL in the sera of animals not receiving probenecid were 76.0 micrograms/ml at 30 min and declined to 7.7 micrograms/ml by 2.0 h. Maximum concentrations in bone were 2.7 micrograms/g in the humerus and 7.1 micrograms/g in the scapula at 1 h. Pretreatment with probenecid significantly elevated levels of AZL in both serum and bone while increasing the half-life in serum from 0.44 to 0.65 h. Maximum drug concentrations in bones of probenecid-pretreated animals were 3.9 and 11.7 micrograms/g in the humerus and scapula, respectively, with detectable levels persisting in bone for up to 4 h. The peak level of CFD alone in serum was 36.7 micrograms/ml at 30 min and declined to 0.86 micrograms/ml at 8 h. Maximum concentrations in bone were 0.66 micrograms/g in the humerus at 1 h and 1.8 micrograms/g in the scapula at 2 h. Pretreatment with probenecid significantly elevated levels of CFD in both serum and bone while increasing the half-life in serum from 1.4 to 2.94 h. Pretreatment with probenecid achieved maximum concentrations of 1.7 and 2.8 micrograms/g in the humerus and scapula, respectively. Detectable levels of CFD persisted in the humerus for up to 4 h and in the scapula for 8 h.