[Antibiotic concentrations in wound secretions and bone during the simultaneous administration of mezlocillin and oxacillin].

Mezlocillin and oxacillin have been used in combination for short-term antibiotic prophylaxis in orthopedic surgery. Antibiotic concentrations were measured in serum, wound secretions from subcutaneous tubings and bone. Half an hour after the i. v. application of 4 g mezlocillin + 2 g oxacillin, the concentrations in wound secretions were 20% of the serum levels. After four hours the levels of both antibiotics in wound secretions increased to 2.66 times the serum levels of mezlocillin, and 5.37 times those of oxacillin. After eight hours the concentrations in wound secretions dropped to about one half, but remained well within therapeutic levels. The parallel course of the concentrations of both antibiotics in wound secretions indicates that mezlocillin and oxacillin have very similar half-lives in wound secretions, although the serum half-lives (t 50% beta) of the two antibiotics are different. The concentrations obtained from cancellous bone were approximately. 10% of the serum levels one to two hours after the antibiotic infusion.