A comparison of the penetration of cefuroxime and cephamandole into bone, fat and haematoma fluid in patients undergoing total hip replacement

Twelve patients undergoing total hip anthroplasty received, at the induction of anaesthesia, cephamandole (1 g) and cefuroxime (1.5 g); further doses of cephamandole (1 g) and cefuroxime (750 mg) were given at 8 and 16 h after the operation. Routine total hip arthroplasty was performed and at timed intervals during operation samples of bone, fat and blood were collected for assay for HPLC analysis. Samples of the haematoma fluid that formed around the operation site and further blood samples were also collected at 7 and 15 h after the operation. Although considerable variation was observed in the bone and fat concentrations of both agents, the cefuroxime levers were substantially higher than those of cephamandole, with mean values for bone of cefuroxime 36.0 mg/L (95% CI 29.0-43.0 mg/L) and cephamandole 18.3 mg/L (95% CI 14.2-22.4 mg/L) and for fat of cefuroxime 15.0 mg/L (95% CI 11.1-18.9 mg/L) and cephamandole 11.2 mg/L (95% CI 7.2-15.2 mg/L). When corrected for blood concentrations the penetration of both agents was similar (bone, 43.6% cefuroxime and 37.8% cephamandole; fat, 16.0% cefuroxime and 19.2% cephamandole). Cefuroxime concentrations in haematoma drain fluid were higher than those of cephamandole 6-8 h after the operation (17.8 versus 8.3 mg/L) but lower at 14-16 h (7.7 versus 9.6 mg/L). We conclude that there are no significant differences between the bone, fat or haematoma penetration of cefuroxime and cephamandole and that any differences in the absolute levels of the two agents are due to differences in the total drug administered rather than their ability to penetrate into these sites. Time-kill curves for cefuroxime and cephamandole against five clinical isolates of Staphylococcus aureus failed to identify any significant differences between the rates of kill for the two agents at the concentrations seen in bone, fat or haematoma fluid. For both prophylaxis regimens antibiotic concentrations exceeded the MICs for potential pathogens for the duration of the operation and also in the haematoma which surrounds the operation site for up to 24 h after the operation.